This&#160;research was supported by NIH 1 U01 HL097973, NHLBI 5 R01 HL116511-02, UCSF-CTSI Grant Number UL1 TR000004, the Robert Wood Johnson Health and Society Scholars Program, and the Lisa and John Pritzker Family Foundation. The authors also wish to acknowledge Michelle Stephens for her assistance with scoring the ANS data as well as Vanessa Tearnan, Marialma Gonzales-Cruz, Yurivia Cervantes, Amy Engler, Stephanie Grover and Karen Jones-Mason for their assistance in collecting the ANS data, and Michael Coccia for his help with the data. We are also thankful to the families for their generous participation in this research and to the volunteers who helped us to test and refine this protocol, including the first author&#8217;s two children. We want to acknowledge our mentors who taught us about measuring ANS and why measuring ANS responsivity is meaningful in young children: W. Thomas Boyce, Gary Bernston, and Dave Lozano.

<ol>
	<li>Berntson, G., Quigley, K., Lozano, D., Cacioppo, J. T., Tassinary, L. G., Bernston, G. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+8,+Cardiovascular+Psychophysiology.">Chapter 8, Cardiovascular Psychophysiology.</a> Handbook of Psychophysiology. , (2007).</li><li>Boyce, W. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+father+involvement+moderates+biobehavioral+susceptibility+to+mental+health+problems+in+middle+childhood.">Early father involvement moderates biobehavioral susceptibility to mental health problems in middle childhood.</a> J. Am. Acad. Child Adolesc. Psychiatry. 45, 1510-1520 (2006).</li><li>Loman, M., Gunnar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+experience+and+the+development+of+stress+reactivity+and+regulation+in+children.">Early experience and the development of stress reactivity and regulation in children.</a> Neurosci. Behav. Physiol. 34, 867-876 (2010).</li><li>Calkins, S. D., Graziano, P. A., Keane, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+vagal+regulation+differentiates+among+children+at+risk+for+behavioral+problems.">Cardiac vagal regulation differentiates among children at risk for behavioral problems.</a> Biol. Psychol. 74, 144-153 (2007).</li><li>Kroenke, C. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autonomic+and+Adrenocortical+Reactivity+and+Buccal+Cell+Telomere+Length+in+Kindergarten+Children.">Autonomic and Adrenocortical Reactivity and Buccal Cell Telomere Length in Kindergarten Children.</a> Psychosom. Med. 73, 533-540 (2011).</li><li>Obradovi&#263;, J., Bush, N. R., Stamperdahl, J., Adler, N. E., Boyce, W. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+sensitivity+to+context:+The+interactive+effects+of+stress+reactivity+and+family+adversity+on+socioemotional+behavior+and+school+readiness.">Biological sensitivity to context: The interactive effects of stress reactivity and family adversity on socioemotional behavior and school readiness.</a> Child Dev. 81, 270-289 (2010).</li><li>Alkon, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Latino+children's+body+mass+index+at+2-3.5+years+predicts+sympathetic+nervous+system+activity+at+5+years.">Latino children's body mass index at 2-3.5 years predicts sympathetic nervous system activity at 5 years.</a> Child Obes. 10, 214-224 (2014).</li><li>Alkon, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ontogeny+of+autonomic+measures+in+6-+and+12-month-old+infants.">The ontogeny of autonomic measures in 6- and 12-month-old infants.</a> Dev. Psychobiol. 48, 197-208 (2006).</li><li>Conradt, E., Measelle, J., Ablow, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poverty,+Problem+Behavior,+and+Promise:+Differential+Susceptibility+Among+Infants+Reared+in+Poverty.">Poverty, Problem Behavior, and Promise: Differential Susceptibility Among Infants Reared in Poverty.</a> Psychol. Sci. 24, 235-242 (2013).</li><li>Alkon, A., Boyce, W. T., Davis, N. V., Eskenazi, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental+Changes+in+Autonomic+Nervous+System+Resting+and+Reactivity+Measures+in+Latino+Children+from+6+to+60+Months+of+Age.">Developmental Changes in Autonomic Nervous System Resting and Reactivity Measures in Latino Children from 6 to 60 Months of Age.</a> J. Dev. Behav. 32, 668-677 (2011).</li><li>Alkon, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental+and+contextual+influences+on+autonomic+reactivity+in+young+children.">Developmental and contextual influences on autonomic reactivity in young children.</a> Dev. Psychobiol. 42, 64-78 (2003).</li><li>Boyce, W. T., Ciccheti, D., Cohen, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Developmental Psychopathology: Developmental Neuroscience. II, 797-817 (2006).</li><li>Beauchaine, T. P., Gatzke-Kopp, L., Mead, H. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyvagal+Theory+and+developmental+psychopathology:+emotion+dysregulation+and+conduct+problems+from+preschool+to+adolescence.">Polyvagal Theory and developmental psychopathology: emotion dysregulation and conduct problems from preschool to adolescence.</a> Biol. Psychol. 74, 174-184 (2007).</li><li> Beauchaine, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vagal+tone,+development,+and+Gray's+motivational+theory:+toward+an+integrated+model+of+autonomic+nervous+system+functioning+in+psychopathology.">Vagal tone, development, and Gray's motivational theory: toward an integrated model of autonomic nervous system functioning in psychopathology.</a> Dev. Psychopathol. 13, 183-214 (2001).</li><li>Conradt, E., Measelle, J., Poverty Ablow, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Problem+Behavior,+and+Promise:+Differential+Suceptibility+Among+Infants+Reared+in+Poverty.">Problem Behavior, and Promise: Differential Suceptibility Among Infants Reared in Poverty.</a> Psychol. Sci. 24, 235-242 (2013).</li><li>Porges, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+polyvagal+perspective.">The polyvagal perspective.</a> Biol. Psychol. 74, 116-143 (2007).</li><li>Boyce, W. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autonomic+reactivity+and+psychopathology+in+middle+childhood.">Autonomic reactivity and psychopathology in middle childhood.</a> Br. J. Psychiatry. 179, 144-150 (2001).</li><li>Crowell, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autonomic+correlates+of+attention-deficit/hyperactivity+disorder+and+oppositional+defiant+disorder+in+preschool+children.">Autonomic correlates of attention-deficit/hyperactivity disorder and oppositional defiant disorder in preschool children.</a> J. Abnorm. Psychol. 115, 174-178 (2006).</li><li>Raine, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autonomic+nervous+system+factors+underlying+disinhibited,+antisocial,+and+violent+behavior.+Biosocial+perspectives+and+treatment+implications.">Autonomic nervous system factors underlying disinhibited, antisocial, and violent behavior. Biosocial perspectives and treatment implications.</a> Ann. N.Y. Acad. Sci. 794, 46-59 (1996).</li><li>Boyce, W. T., Alkon, A., Tschann, J. M., Chesney, M. A., Alpert, B. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dimensions+of+psychobiologic+reactivity:+Cardiovascular+responses+to+laboratory+stressors+in+preschool+children.">Dimensions of psychobiologic reactivity: Cardiovascular responses to laboratory stressors in preschool children.</a> Ann. Behav. Med. 17, 315-323 (1995).</li><li>Bush, N. R., Boyce, W. T., Lewis, M., Rudolph, K. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Contributions+of+Early+Experience+to+Biological+Development+and+Sensitivity+to+Context.">The Contributions of Early Experience to Biological Development and Sensitivity to Context.</a> Handbook of Developmental Psychopathology. , 287-309 (2014).</li><li>Matthews, K. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Stress, Reactivity, and Cardiovascular Disease. , (1986).</li><li>Alkon, A., Wolff, B., Boyce, W., Maholmes, V., King, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Oxford Handbook of Poverty and Child Development. , (2012).</li><li>Berntson, G. G., Cacioppo, J. T., Quigley, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autonomic+cardiac+control.+I.+Estimation+and+validation+from+pharmacological+blockades.">Autonomic cardiac control. I. Estimation and validation from pharmacological blockades.</a> Psychophysiology. 31, 572-585 (1994).</li><li>Sherwood, A., Allen, M. T., Obrist, P. A., Langer, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+beta-adrenergic+influences+on+cardiovascular+and+metabolic+adjustments+to+physical+and+psychological+stress.">Evaluation of beta-adrenergic influences on cardiovascular and metabolic adjustments to physical and psychological stress.</a> Psychophysiology. 23, 89-104 (1986).</li><li>Calkins, S. D., Keane, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+vagal+regulation+across+the+preschool+period:+Stability,+continuity,+and+implications+for+childhood+adjustment.">Cardiac vagal regulation across the preschool period: Stability, continuity, and implications for childhood adjustment.</a> Dev. Psychobiol. 45, 101-112 (2004).</li><li>Quigley, K., Stifter, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparative+validation+of+sympathetic+reactivity+in+children+and+adults.">A comparative validation of sympathetic reactivity in children and adults.</a> Psychophysiology. 43, 116-143 (2006).</li><li>Sherwood, A., Royal, S., Hutcheson, J., Turner, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+impedance+cardiographic+measurements+using+band+and+spot+electrodes.">Comparison of impedance cardiographic measurements using band and spot electrodes.</a> Psychophysiology. 29, 734-741 (1992).</li><li>Allen, M. T., Matthews, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemodynamic+responses+to+laboratory+stressors+in+children+and+adolescents:+the+influences+of+age,+race,+and+gender.">Hemodynamic responses to laboratory stressors in children and adolescents: the influences of age, race, and gender.</a> Psychophysiology. 34, 329-339 (1997).</li><li>van Dijk, A. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+cardiac+autonomic+nervous+system+(ANS)+activity+in+children.">Measuring cardiac autonomic nervous system (ANS) activity in children.</a> J. Vis. Exp. , (2013).</li><li>Treadwell, M. J., Alkon, A., Styles, L., Boyce, W. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autonomic+nervous+system+reactivity:+children+with+and+without+sickle+cell+disease.">Autonomic nervous system reactivity: children with and without sickle cell disease.</a> Nurs. Res. 60, 197-207 (2011).</li><li>Stifter, C. A., Dollar, J. M., Cipriano, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperament+and+emotion+regulation:+the+role+of+autonomic+nervous+system+reactivity.">Temperament and emotion regulation: the role of autonomic nervous system reactivity.</a> Dev. Psychobiol. 53, 266-279 (2011).</li><li>Bar-Haim, Y., Marshall, P. J., Fox, N. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental+changes+in+heart+period+and+high-frequency+heart+period+variability+from+4+months+to+4+years+of+age.">Developmental changes in heart period and high-frequency heart period variability from 4 months to 4 years of age.</a> Dev. Psychobiol. 37, 44-56 (2000).</li><li>Beauchaine, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiological+Markers+of+Emotional+and+Behavioral+Dysregulation+in+Externalizing+Psychopathology.">Physiological Markers of Emotional and Behavioral Dysregulation in Externalizing Psychopathology.</a> Monogr. Soc. Res. 77, 79-86 (2012).</li><li>Kamarck, T. W., Lovallo, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+reactivity+to+psychological+challege:+Conceptual+and+measurement+considerations.">Cardiovascular reactivity to psychological challege: Conceptual and measurement considerations.</a> Psychosom. Med. 65, 9-21 (2003).</li><li>Fox, N. A., Schmidt, L. A., Henderson, H. A., Marshall, P. J., Cacioppo, J. T., Tassinary, L. G., Bernston, G. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+20,+Developmental+Psychophysiology:+Conceptual+and+Methodological+Issues.">Chapter 20, Developmental Psychophysiology: Conceptual and Methodological Issues.</a> Handbook of Psychophysiology. , 453-481 (2007).</li><li>Gilissen, R., Koolstra, C., van Ijzendoorn, M., Bakermans-Kranenburg, M., van der Veer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiological+reactions+of+preschoolers+to+fear-inducing+film+clips:+Effects+of+temperamental+fearfulness+and+quality+of+the+parent-child+relationship.">Physiological reactions of preschoolers to fear-inducing film clips: Effects of temperamental fearfulness and quality of the parent-child relationship.</a> Dev. Psychobiol. 49, 187-195 (2007).</li><li>Bush, N. R., Alkon, A., Stamperdahl, J., Obradovi&#263;, J., Boyce, W. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiating+Challenge+Reactivity+from+Psychomotor+Activity+in+Studies+of+Children’s+Psychophysiology:+Considerations+for+Theory+and+Measurement.">Differentiating Challenge Reactivity from Psychomotor Activity in Studies of Children’s Psychophysiology: Considerations for Theory and Measurement.</a> J. Exp. Child Psychol. 110, 62-79 (2011).</li></ol>

The authors declare that they have no competing financial interests.

This study revealed that, within a sample of 18 month-old children, standardized resting and challenge tasks designed to elicit responses from a range of domains (startle, sensory, social, resting) led to a range of ANS responses. The mean ANS responses found under these resting and challenge conditions were similar to ANS values reported by others who have measured ANS responsiveness with young children using similar tasks 8,11,27,29. The mean levels of the ANS measures found in our sample are between those t...

Individual differences in children&#8217;s autonomic nervous system (ANS) reactivity play an important role in the development and maintenance of physical and mental health problems 12-16. A growing body of evidence reveals that individual differences in ANS measures at rest and reactivity are predictive of variations in children&#8217;s internalizing and externalizing psychopathology 4,9,17-19 and physical health 7,20. In addition to these direct or main effects of ANS functioning, an accumulating body of studies have found that children&#8217;s reactivity can interact with contextual risk factors, such as adverse events or marital conflict, to moderate those effects on children&#8217;s wellbeing and health (see reference&#160;21 for a review). Despite this growing evidence that children&#8217;s autonomic reactivity plays a role in health across the life course, and the accompanying interest in those processes, there is need for additional research examining the development of ANS functioning in children under three years of age.
The ANS consists of two branches, the parasympathetic and sympathetic nervous systems. It regulates the function of internal organs (e.g.,&#160;heart rate, respiration, digestion, and sexual arousal), largely through unconscious mechanisms, in response to everyday and adverse experiences 1. The parasympathetic nervous system (PNS) is the &#8216;rest and restorative&#8217; system that maintains a low resting heart rate and restorative state when sleeping or relaxing The sympathetic nervous system (SNS) is the &#8216;fight or flight&#8217; system that responds to emergencies or threatening situations by accelerating one&#8217;s heart rate 23. Respiratory sinus arrhythmia (RSA) is a reliable index of the PNS influence on cardiac functioning, and pre-ejection period (PEP) is a reliable index of the SNS influence on cardiac functioning. Both RSA and PEP have been found to be valid measures through experimental pharmacological blockade in samples of adults 24,25. More recently, this work has been extended into child and adolescent samples, further establishing RSA and PEP as valid and reliable measures of ANS activity throughout development 8,26,27. Reliable impedance cardiography measurements (PEP) using band and spot electrodes have been used for considerable time in adult samples 28. More recently, parallel measurement and analytic techniques have also been shown to be reliable and valid in samples of children 11,29,30, although collection of PEP measures in young children is rare.
There is an extant large body of literature on PNS functioning in infants and young children, including vagal tone and respiratory sinus arrhythmia measures. There are fewer studies of the SNS using PEP, and very few simultaneously examining both the parasympathetic and sympathetic nervous systems, which is critical for building understanding of their highly integrated functioning. Of the few studies of young children&#8217;s PEP, most find that their protocols do not produce significant group level changes in PEP in response to challenges 8,31. Studies have demonstrated that there is stability in resting PNS measures starting in infancy and they have relations with temperament, behavior, and health,13,16,26,32,33 but there is a limited understanding of SNS responding and its stability over time, relations to development, and the factors that shape that its developmental trajectory. PNS responses have been attributed primarily to social engagement 16 and SNS responses proposed to reflect &#8220;fight or flight responses&#8221; 1 as well as reward sensitivity (see reference&#160;34 for a review). In young children, it is challenging to simulate specific challenges in a laboratory and to engage them due to their short attention span. There are also measurement challenges for toddlers who may experience discomfort with the seven spot electrodes needed to measure PNS and SNS simultaneously. In addition, within the fields of developmental science, there few standards about how to elicit &#8220;stress reactivity&#8221; sufficiently while also respecting children&#8217;s developmental needs and the ethics in working with children. This article presents information on the administration and scoring of a standardized protocol comprised of resting and challenging conditions designed to elicit parasympathetic and sympathetic nervous system responses from 18 month old children.
ANS reactivity is typically conceptualized as the physiological response to a discrete external stimulus relative to a comparison or resting state, which varies across individual organisms 22. Examination of the early life etiology of mental and physical health problems has led scientists to be particularly interested in understanding children&#8217;s reactivity to situations that evoke adaptive responding or can be thought of as stressful challenges. The preponderance of literature refers to this phenomenon as &#8220;stress reactivity&#8221;, although encountering challenging stimuli has the potential to elicit responses across a broad range of domains. Thus, the protocol described below was designed to elicit ANS responses across multiple domains including two forms of rest (while listening to a soothing lullaby and while watching a calm, neutral video) and three developmentally-appropriate challenges for 18-month olds: anticipation/startle (jack-in-the-box), sensory (lemon juice), and socioemotional (listening to a sick infant cry). The protocol was adapted from our existing protocols for 12 month olds 8 and 3-5 year olds 11, in order to make it developmentally-challenging, engaging and tolerable for toddlers (18-21 months).
Here we present the Developmental Challenges Protocol (DCP) and ANS data from the 18 month old study visit of the Stress, Eating and Early Development (SEED) Study of pregnant women and their offspring. Maternal participants with healthy pregnancies were recruited&#160;during 2013-14 for a study of gestational weight gain and prenatal stress and were overweight, low income, and racially and ethnically diverse. Parents&#8217; informed consent for the study of her offspring was obtained just after birth and again prior to the start of the data collection for the study reported here, when the offspring were 18-21 months of age during 2014-2015.

<table>
	<tbody>
		<tr>
			<td>ANS equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Laptop and power cord&#160;</td>
			<td>Dell</td>
			<td>60-0107-3.0</td>
			<td>Mindware BioLab software requires a PC with 2 USB ports</td>
		</tr>
		<tr>
			<td>ANS data collection software</td>
			<td>Mindware</td>
			<td>contact company</td>
			<td>BioLab acquisition program</td>
		</tr>
		<tr>
			<td>ANS data acquisition unit and cords</td>
			<td>Mindware</td>
			<td>50-3711-08</td>
			<td>BioNex 8-slot Chassis</td>
		</tr>
		<tr>
			<td>Snap leads</td>
			<td>Mindware</td>
			<td>93-0498-00</td>
			<td>2 white, 2 red, 2 brown, 1 black</td>
		</tr>
		<tr>
			<td>Spot electrodes</td>
			<td>Kendall</td>
			<td>31112496</td>
			<td>130 model; 7 for each assessment + extras-to be sealed in a ziplock bag at all times)</td>
		</tr>
		<tr>
			<td>ANS scoring/editing software</td>
			<td>Mindware</td>
			<td>contact company</td>
			<td>HRV Analysis, version 3.1.0F and IMP Analysis, version 3.1.0I</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Protocol equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>tablet computer</td>
			<td>Apple</td>
			<td></td>
			<td>iPad; for playing audio and video clips</td>
		</tr>
		<tr>
			<td>portable speaker</td>
			<td>Polariod</td>
			<td>PBT510</td>
			<td></td>
		</tr>
		<tr>
			<td>Jack in the Box</td>
			<td>Schylling</td>
			<td>SMJB</td>
			<td>Sock Monkey theme</td>
		</tr>
		<tr>
			<td>Lemon juice</td>
			<td>ReaLemon</td>
			<td>98077</td>
			<td>0.14oz shelf-stable packets</td>
		</tr>
		<tr>
			<td>Pasture pipettes</td>
			<td>Grainger</td>
			<td>6FAV9</td>
			<td>1 ml size, disposable</td>
		</tr>
		<tr>
			<td>Portion cups</td>
			<td>Dart Solo Con</td>
			<td>250PC</td>
			<td>2.5 oz, disposable, plastic</td>
		</tr>
		<tr>
			<td>audio files of baby cry</td>
			<td>Alkon lab</td>
			<td></td>
			<td>30 second clip recorded in a neonatal intensive care unit</td>
		</tr>
		<tr>
			<td>audio file of baseline lullaby</td>
			<td>Rockabye Baby Music</td>
			<td></td>
			<td>60 seconds of &#34;Across the Universe&#34; on &#34;Rockabye Baby Lullaby Renditions of the Beatles&#34; CD</td>
		</tr>
		<tr>
			<td>audio file of final lullaby</td>
			<td>Rockabye Baby Music</td>
			<td></td>
			<td>60 seconds of &#34;Here Comes the Sun&#34; on &#34;Rockabye Baby Lullaby Renditions of the Beatles&#34; CD</td>
		</tr>
		<tr>
			<td>video file of neutral video</td>
			<td></td>
			<td></td>
			<td>2 minutes of Baby Einstein video</td>
		</tr>
		<tr>
			<td>Retractable measuring tape</td>
			<td>Rollfix</td>
			<td>TM04</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Miscellaneous materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Surge protector</td>
			<td></td>
			<td></td>
			<td>to plug in all electronics</td>
		</tr>
		<tr>
			<td>2-prong adapter for surge protector</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Video camera</td>
			<td>Sony</td>
			<td></td>
			<td>Handycam HDR-CX440</td>
		</tr>
		<tr>
			<td>Video Encoder, power and input cords</td>
			<td>Mindware</td>
			<td>50-8614-01</td>
			<td>optional; to sync video and ANS data files</td>
		</tr>
		<tr>
			<td>Baby wipes and gauze</td>
			<td></td>
			<td></td>
			<td>for cleaning and drying oily skin</td>
		</tr>
		<tr>
			<td>Toys</td>
			<td></td>
			<td></td>
			<td>to distract children during assessment</td>
		</tr>
		<tr>
			<td>Visual aids</td>
			<td></td>
			<td></td>
			<td>pictures of child with electrodes on, description of protocol to show participants</td>
		</tr>
		<tr>
			<td>Script of protocol for research assistants</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Charging cords for tablet and speaker</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Doll and reinforcer</td>
			<td></td>
			<td></td>
			<td>for demonstration if necessary</td>
		</tr>
	</tbody>
</table>

measuring cardiac autonomic nervous system (ans) activity in toddlers - resting and developmental challenges

The autonomic nervous system (ANS) consists of two branches, the parasympathetic and sympathetic nervous systems, and controls the function of internal organs (e.g., heart rate, respiration, digestion) and responds to everyday and adverse experiences 1. ANS measures in children have been found to be related to behavior problems, emotion regulation, and health 2-7. Therefore, understanding the factors that affect ANS development during early childhood is important. Both branches of the ANS affect young children&#8217;s cardiovascular responses to stimuli and have been measured noninvasively, via external monitoring equipment, using valid and reliable measures of physiological change 8-11. However, there are few studies of very young children with simultaneous measures of the parasympathetic and sympathetic nervous systems, which limits understanding of the integrated functioning of the two systems. In addition, the majority of existing studies of young children report on infants&#8217; resting ANS measures or their reactivity to commonly used mother-child interaction paradigms, and less is known about ANS reactivity to other challenging conditions. We present a study design and standardized protocol for a non-invasive and rapid assessment of cardiac autonomic control in 18 month old children. We describe methods for continuous monitoring of the parasympathetic and sympathetic branches of the ANS under resting and challenge conditions during a home or laboratory visit and provide descriptive findings from our sample of 140 ethnically diverse toddlers using validated equipment and scoring software. Results revealed that this protocol can produce a range of&#160;physiological responses to both resting and developmentally challenging conditions, as indicated by changes in heart rate and indices of parasympathetic and sympathetic activity. Individuals demonstrated&#160;variability in resting levels, responses to challenges, and challenge reactivity, which provides additional evidence that this protocol is useful for the examination of ANS individual differences for toddlers.

The SEED study enrolled&#160;162&#160;mother-child dyads (37% African American; 30% Latina; 16% white; 17% other or multiracial). For the 18 month visit, we completed the in-person assessment with 140 children (87% of the enrolled sample); 6 participants moved away, and the remaining participants were unreachable or unavailable for this visit. The refusal rate for ANS data collection component of the visit was 3/140 (2%) for mothers available for this visit. Three visits were conducted after 21 months (more than 3 months...

Watch this Scientific Journal Video about Measuring Cardiac Autonomic Nervous System ANS Activity in Toddlers - Resting and Developmental Challenges at JoVE.com

Measuring Cardiac Autonomic Nervous System ANS Activity in Toddlers - Resting and Developmental Challenges

We describe the methods for continuous monitoring of the autonomic nervous system under resting and challenge conditions with 18 month old children. Results revealed that this protocol can produce meaningful physiological responses in both branches of the autonomic nervous system and elicit significant individual variability in patterns of responses.

Measuring Cardiac Autonomic Nervous System (ANS) Activity in Toddlers - Resting and Developmental Challenges

The autonomic nervous system (ANS) consists of two branches, the parasympathetic and sympathetic nervous systems, and controls the function of internal ...

measuring-cardiac-autonomic-nervous-system-ans-activity-toddlers

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Introduction to Psychology

Anatomy and Physiology

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Unit 1

Biopsychology

The Autonomic Nervous System

SCIENTISTS IN ACTION

15.2K 次观看.  University of California, San Francisco. 我们描述了与18个月大的孩子休息和挑战的条件下连续监测的自主神经系统的方法。结果表明，该协议能产生有意义的生理反应的自主神经系统的两个分支和响应模式引起显著的个体差异。 

视频: Measuring Cardiac Autonomic Nervous System ANS Activity in Toddlers - Resting and Developmental Challenges

Quantitative Autonomic Testing

Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be invaluable tool for evaluation of these disorders, both in clinic and research. There are number of autonomic tests, however, only few were validated clinically or are quantitative. Here, fully quantitative and clinically validated protocol for testing of autonomic functions is presented. As a bare minimum the clinical autonomic laboratory should have a tilt table, ECG monitor, continuous noninvasive blood pressure monitor, respiratory monitor and a mean for evaluation of sudomotor domain. The software for recording and evaluation of autonomic tests is critical for correct evaluation of data. The presented protocol evaluates 3 major autonomic domains: cardiovagal, adrenergic and sudomotor. The tests include deep breathing, Valsalva maneuver, head-up tilt, and quantitative sudomotor axon test (QSART). The severity and distribution of dysautonomia is quantitated using Composite Autonomic Severity Scores (CASS). Detailed protocol is provided highlighting essential aspects of testing with emphasis on proper data acquisition, obtaining the relevant parameters and unbiased evaluation of autonomic signals. The normative data and CASS algorithm for interpretation of results are provided as well.

Standardized, comprehensive and fully quantitative testing of autonomic functions is described. The autonomic tests consist of evaluation of all three major autonomic domains including cardiovagal, adrenergic and sudomotor. The severity and distribution of dysautonomia is quantitated using Composite Autonomic Severity Scores.

Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be ...

Portable Intermodal Preferential Looking (IPL): Investigating Language Comprehension in Typically Developing Toddlers and Young Children with Autism

One of the defining characteristics of autism spectrum disorder (ASD) is difficulty with language and communication.1 Children with ASD's onset of speaking is usually delayed, and many children with ASD consistently produce language less frequently and of lower lexical and grammatical complexity than their typically developing (TD) peers.6,8,12,23 However, children with ASD also exhibit a significant social deficit, and researchers and clinicians continue to debate the extent to which the deficits in social interaction account for or contribute to the deficits in language production.5,14,19,25
Standardized assessments of language in children with ASD usually do include a comprehension component; however, many such comprehension tasks assess just one aspect of language (e.g., vocabulary),5 or include a significant motor component (e.g., pointing, act-out), and/or require children to deliberately choose between a number of alternatives. These last two behaviors are known to also be challenging to children with ASD.7,12,13,16
We present a method which can assess the language comprehension of young typically developing children (9-36 months) and children with autism.2,4,9,11,22 This method, Portable Intermodal Preferential Looking (P-IPL), projects side-by-side video images from a laptop onto a portable screen. The video images are paired first with a 'baseline' (nondirecting) audio, and then presented again paired with a 'test' linguistic audio that matches only one of the video images. Children's eye movements while watching the video are filmed and later coded. Children who understand the linguistic audio will look more quickly to, and longer at, the video that matches the linguistic audio.2,4,11,18,22,26
This paradigm includes a number of components that have recently been miniaturized (projector, camcorder, digitizer) to enable portability and easy setup in children's homes. This is a crucial point for assessing young children with ASD, who are frequently uncomfortable in new (e.g., laboratory) settings. Videos can be created to assess a wide range of specific components of linguistic knowledge, such as Subject-Verb-Object word order, wh-questions, and tense/aspect suffixes on verbs; videos can also assess principles of word learning such as a noun bias, a shape bias, and syntactic bootstrapping.10,14,17,21,24 Videos include characters and speech that are visually and acoustically salient and well tolerated by children with ASD.

Portable Intermodal Preferential Looking IPL: Investigating Language Comprehension in Typically Developing Toddlers and Young Children with Autism

A reliable home-based way to assess the language comprehension of very young typically developing children, as well as those with autism, is described. The method analyzes children's eye gaze while viewing side-by-side images but hearing an audio that matches only one image. Stimuli are designed with young participants in mind.

One  of the defining characteristics of autism spectrum disorder (ASD) is difficulty  with language and communication.1  Children with ASD's onset of ...

Measuring Cardiac Autonomic Nervous System (ANS) Activity in Children

The autonomic nervous system (ANS) controls mainly automatic bodily functions that are engaged in homeostasis, like heart rate, digestion, respiratory rate, salivation, perspiration and renal function. The ANS has two main branches: the sympathetic nervous system, preparing the human body for action in times of danger and stress, and the parasympathetic nervous system, which regulates the resting state of the body.
ANS activity can be measured invasively, for instance by radiotracer techniques or microelectrode recording from superficial nerves, or it can be measured non-invasively by using changes in an organ's response as a proxy for changes in ANS activity, for instance of the sweat glands or the heart. Invasive measurements have the highest validity but are very poorly feasible in large scale samples where non-invasive measures are the preferred approach. Autonomic effects on the heart can be reliably quantified by the recording of the electrocardiogram (ECG) in combination with the impedance cardiogram (ICG), which reflects the changes in thorax impedance in response to respiration and the ejection of blood from the ventricle into the aorta. From the respiration and ECG signals, respiratory sinus arrhythmia can be extracted as a measure of cardiac parasympathetic control. From the ECG and the left ventricular ejection signals, the preejection period can be extracted as a measure of cardiac sympathetic control. ECG and ICG recording is mostly done in laboratory settings. However, having the subjects report to a laboratory greatly reduces ecological validity, is not always doable in large scale epidemiological studies, and can be intimidating for young children. An ambulatory device for ECG and ICG simultaneously resolves these three problems.
Here, we present a study design for a minimally invasive and rapid assessment of cardiac autonomic control in children, using a validated ambulatory device 1-5, the VU University Ambulatory Monitoring System (VU-AMS, Amsterdam, the Netherlands,<a href="http://www.vu-ams.nl" target="_blank"> www.vu-ams.nl</a>).

Measuring Cardiac Autonomic Nervous System ANS Activity in Children

Measurement of autonomic nervous system activity usually confines the researcher and participant to the laboratory, which may provide an intimidating environment to children. The VU University Ambulatory Monitoring System (VU-AMS) device can record cardiac autonomic control in any setting. The VU-AMS proved very amenable to testing in children.

The autonomic nervous system (ANS) controls mainly automatic bodily functions that are engaged in homeostasis, like heart rate, digestion, respiratory ...

Carotid Artery Infusions for Pharmacokinetic and Pharmacodynamic Analysis of Taxanes in Mice

When proposing the use of a drug, drug combination, or drug delivery into a novel system, one must assess the pharmacokinetics of the drug in the study model. As the use of mouse models are often a vital step in preclinical drug discovery and drug development1-8, it is necessary to design a system to introduce drugs into mice in a uniform, reproducible manner. Ideally, the system should permit the collection of blood samples at regular intervals over a set time course. The ability to measure drug concentrations by mass-spectrometry, has allowed investigators to follow the changes in plasma drug levels over time in individual mice1, 9, 10. In this study, paclitaxel was introduced into transgenic mice as a continuous arterial infusion over three hours, while blood samples were simultaneously taken by retro-orbital bleeds at set time points. Carotid artery infusions are a potential alternative to jugular vein infusions, when factors such as mammary tumors or other obstructions make jugular infusions impractical. Using this technique, paclitaxel concentrations in plasma and tissue achieved similar levels as compared to jugular infusion. In this tutorial, we will demonstrate how to successfully catheterize the carotid artery by preparing an optimized catheter for the individual mouse model, then show how to insert and secure the catheter into the mouse carotid artery, thread the end of the catheter out through the back of the mouse&#8217;s neck, and hook the mouse to a pump to deliver a controlled rate of drug influx. Multiple low volume retro-orbital bleeds allow for analysis of plasma drug concentrations over time.

This method was developed with the goal of delivering a steady drug solution via the carotid artery, to assess the pharmacokinetics of novel drugs in mouse models.

When proposing the use of a drug, drug combination, or drug delivery into a novel system, one must assess the pharmacokinetics of the drug in the study ...

Electrophysiological Measurement of Noxious-evoked Brain Activity in Neonates Using a Flat-tip Probe Coupled to Electroencephalography

Pain is an unpleasant sensory and emotional experience. In non-verbal patients, it is very difficult to measure pain, even with pain assessment tools. Those tools are subjective or determine secondary physiological indicators which also have certain limitations particularly when exploring the effectiveness of analgesia. As cortical processing is essential for pain perception, brain activity measures may provide a useful approach to assess pain in infants. Here we present a method to assess nociception with electrophysiological brain activity recordings optimized for the use in newborn infants. To produce highly standardized and reproducible noxious stimuli we applied mechanical stimulation with a flat-tip probe, e.g., PinPrick, which is not skin-breaking and does not cause behavioral distress. The noxious-evoked potential allows the objective measurement of nociception in non-verbal patients. This method can be used in newborn infants as early as 34 weeks of gestational age. Moreover, it could be applied in different situations such as measuring the efficacy of analgesic or anesthetic drugs.

Measuring pain in non-verbal patients is a challenge. In this study we combine EEG recording with stimulation using a flat-tip probe to detect noxious-evoked brain activity in an objective manner.

Pain is an unpleasant sensory and emotional experience. In non-verbal patients, it is very difficult to measure pain, even with pain assessment tools. ...

A Drosophila In Vivo Injury Model for Studying Neuroregeneration in the Peripheral and Central Nervous System

The regrowth capacity of damaged neurons governs neuroregeneration and functional recovery after nervous system trauma. Over the past few decades, various intrinsic and extrinsic inhibitory factors involved in the restriction of axon regeneration have been identified. However, simply removing these inhibitory cues is insufficient for successful regeneration, indicating the existence of additional regulatory machinery. Drosophila melanogaster, the fruit fly, shares evolutionarily conserved genes and signaling pathways with vertebrates, including humans. Combining the powerful genetic toolbox of flies with two-photon laser axotomy/dendriotomy, we describe here the Drosophila sensory neuron &#8211; dendritic arborization (da) neuron injury model as a platform for systematically screening for novel regeneration regulators. Briefly, this paradigm includes a) the preparation of larvae, b) lesion induction to dendrite(s) or axon(s) using a two-photon laser, c) live confocal imaging post-injury and d) data analysis. Our model enables highly reproducible injury of single labeled neurons, axons, and dendrites of well-defined neuronal subtypes, in both the peripheral and central nervous system.

A Drosophila In Vivo Injury Model for Studying Neuroregeneration in the Peripheral and Central Nervous System

Here, we present a protocol using the Drosophila sensory neuron - dendritic arborization (da) neuron injury model, which combines in vivo live imaging, two-photon laser axotomy/dendriotomy, and the powerful fly genetic toolbox, as a platform for screening potential promoters and inhibitors of neuroregeneration.

The regrowth capacity of damaged neurons governs neuroregeneration and functional recovery after nervous system trauma. Over the past few decades, various ...

Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System

Since its invention in the late 19th century, the Langendorff ex vivo heart perfusion system continues to be a relevant tool for studying a broad spectrum of physiological, biochemical, morphological, and pharmacological parameters in centrally denervated hearts. Here, we describe a setup for the modulation of the intracardiac autonomic nervous system and the assessment of its influence on basic electrophysiology, arrhythmogenesis, and cyclic adenosine monophosphate (cAMP) dynamics. The intracardiac autonomic nervous system is modulated by the mechanical dissection of atrial fat pads-in which murine ganglia are located mainly&#8212;or by the usage of global as well as targeted pharmacological interventions. An octapolar electrophysiological catheter is introduced into the right atrium and the right ventricle, and epicardial-placed multi-electrode arrays (MEA) for high-resolution mapping are used to determine cardiac electrophysiology and arrhythmogenesis. F&#246;rster resonance energy transfer (FRET) imaging is performed for the real-time monitoring of cAMP levels in different cardiac regions. Neuromorphology is studied by means of antibody-based staining of whole hearts using neuronal markers to guide the identification and modulation of specific targets of the intracardiac autonomic nervous system in the performed studies. The ex vivo Langendorff setup allows for a high number of reproducible experiments in a short time. Nevertheless, the partly open nature of the setup (e.g., during MEA measurements) makes constant temperature control difficult and should be kept to a minimum. This described method makes it possible to analyze and modulate the intracardiac autonomic nervous system in decentralized hearts.

Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System

Here, we present a protocol for the modulation of the intracardiac autonomic nervous system and the assessment of its influence on basic electrophysiology, arrhythmogenesis, and cAMP dynamics using an ex vivo Langendorff setup.

Since its invention in the late 19th century, the Langendorff ex vivo heart perfusion system continues to be a relevant tool for studying a broad spectrum ...

A Flow Cytometry-based Assay for Measuring Mitochondrial Membrane Potential in Cardiac Myocytes After Hypoxia/Reoxygenation

Timely and efficient reperfusion of the occluded coronary artery is the best strategy for decreasing myocardial infarct size in patients with a ST-segment elevated myocardial infarction. However, reperfusion per se can result in further cardiomyocyte death, a phenomenon known as reperfusion injury. The opening of the mitochondrial permeability transition pore (mPTP), with the decrease of the mitochondrial membrane potential (MMP), or mitochondrial depolarization, is universally recognized as the final step of reperfusion injury and is responsible for mitochondrial and cardiomyocyte death. JC-1 is a lipophilic cationic dye that accumulates in mitochondria depending on the value of MMP. The higher the MMP is, the more JC-1 accumulates in the mitochondria. The increasing amounts of JC-1 in mitochondria can be reflected by a fluorescence emission shift from green (~530 nm) to red (~590 nm). Therefore, the reduction of the red/green fluorescence intensity ratio can indicate the depolarization of mitochondria. Here, we take advantage of JC-1 to measure MMP, or the opening of mPTP in human cardiac myocytes after hypoxia/reoxygenation, detected by flow cytometry.

Here, we present a protocol that uses JC-1 dye to assess the mitochondrial membrane potential of cells after being exposed to hypoxia/reoxygenation with or without a protective agent.

Timely and efficient reperfusion of the occluded coronary artery is the best strategy for decreasing myocardial infarct size in patients with a ST-segment ...

Semi-Minimal Invasive Method to Induce Myocardial Infarction in Rats and the Assessment of Cardiac Function by an Isolated Working Heart System

Myocardial infarction (MI) remains the main contributor to morbidity and mortality worldwide. Therefore, research on this topic is mandatory. An easily and highly reproducible MI induction procedure is required to obtain further insight and better understanding of the underlying pathological changes. This procedure can also be used to evaluate the effects or potency of new and promising treatments (as drugs or interventions) in acute MI, subsequent remodeling and heart failure (HF). After intubation and pre-operative preparation of the animal, an anesthetic protocol with isoflurane was performed, and the surgical procedure was conducted&#160;quickly. Using a minimally invasive approach, the left anterior descending artery (LAD) was located and occluded by a ligature. The occlusion can be performed acutely for subsequent reperfusion (ischemia/reperfusion injury). Alternatively, the vessel can be ligated permanently to investigate the development of chronic MI, remodeling or HF. Despite common pitfalls, the drop-out rates are minimal. Various treatments such as remote ischemic conditioning can be examined for their cardioprotective potential pre-, peri- and post-operatively. The post-operative recovery was quick as the anesthesia was precisely controlled and the duration of the operation was short. Post-operative analgesia was administered for three days. The minimally invasive procedure reduces the risk of infection and inflammation. Furthermore, it facilitates rapid recovery. The &#8220;working heart&#8221; measurements were performed ex vivo and enabled precise control of preload, afterload and flow. This procedure requires specific equipment and training for adequate performance. This manuscript provides a detailed step-by-step introduction for conducting these measurements.

This article presents an efficient method to perform myocardial ischemia and subsequent chronic reperfusion in rats using a minimally invasive approach. In addition, left ventricular hemodynamic function of rats is assessed by echocardiography and isolated working heart methods.&#160;

Myocardial infarction (MI) remains the main contributor to morbidity and mortality worldwide. Therefore, research on this topic is mandatory. An easily ...

In vitro Assessment of Cardiac Reprogramming by Measuring Cardiac Specific Calcium Flux with a GCaMP3 Reporter

Cardiac reprogramming has become a potentially promising therapy to repair a damaged heart. By introducing multiple transcription factors, including Mef2c, Gata4, Tbx5 (MGT), fibroblasts can be reprogrammed into induced cardiomyocytes (iCMs). These iCMs, when generated in situ in an infarcted heart, integrate electrically and mechanically with the surrounding myocardium, leading to a reduction in scar size and an improvement in heart function. Because of the relatively low reprogramming efficiency, purity, and quality of the iCMs, characterization of iCMs remains a challenge. The currently used methods in this field, including flow cytometry, immunocytochemistry, and qPCR, mainly focus on cardiac-specific gene and protein expression but not on the functional maturation of iCMs. Triggered by action potentials, the opening of voltage-gated calcium channels in cardiomyocytes leads to a rapid influx of calcium into the cell. Therefore, quantifying the rate of calcium influx is a promising method to evaluate cardiomyocyte function. Here, the protocol introduces a method to evaluate iCM function by calcium (Ca2+) flux. An &#945;MHC-Cre/Rosa26A-Flox-Stop-Flox-GCaMP3 mouse strain was established by crossing Tg(Myh6-cre)1Jmk/J (referred to as Myh6-Cre below) with Gt(ROSA)26Sortm38(CAG-GCaMP3)Hze/J (referred to as Rosa26A-Flox-Stop-Flox-GCaMP3 below) mice. Neonatal cardiac fibroblasts (NCFs) from P0-P2 neonatal mice were isolated and cultured in vitro, and a polycistronic construction of MGT was introduced to NCFs, which led to their reprogramming to iCMs. Because only successfully reprogrammed iCMs will express GCaMP3 reporter, the functional maturation of iCMs can be visually assessed by Ca2+ flux with fluorescence microscopy. Compared with un-reprogrammed NCFs, NCF-iCMs showed significant calcium transient flux and spontaneous contraction, similar to CMs. This protocol describes in detail the mouse strain establishment, isolation and selection of neonatal mice hearts, NCF isolation, production of retrovirus for cardiac reprogramming, iCM induction, the evaluation of iCM Ca2+ flux using our reporter line, and related statistical analysis and data presentation. It is expected that the methods described here will provide a valuable platform to assess the functional maturation of iCMs for cardiac reprogramming studies.

We describe here, the establishment and application of an Tg(Myh6-cre)1Jmk/J /Gt(ROSA)26Sortm38(CAG-GCaMP3)Hze/J (referred to as &#945;MHC-Cre/Rosa26A-Flox-Stop-Flox-GCaMP3 below) mouse reporter line for cardiac reprogramming assessment. Neonatal cardiac fibroblasts (NCFs) isolated from the mouse strain are converted into induced cardiomyocytes (iCMs), allowing for convenient and efficient evaluation of reprogramming efficiency and functional maturation of iCMs via calcium (Ca2+) flux.

Cardiac reprogramming has become a potentially promising therapy to repair a damaged heart. By introducing multiple transcription factors, including ...