SYMPATHETIC AND PARASYMPATHETIC CONTROL OF HEART RATE RESPONSE TO RESTRAINT STRESS DURING THE VULNERABLE PERIOD IN NEWBORN RATS

概要

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Newborn infants and animals undergo dramatic development of the autonomic nervous system ; however, there remains a lack of normative information concerning the vulnerable period. This study investigated the maturation of the heart rate (HR) and the autonomic regulation of HR responses to restraint stress during the first 2 postnatal weeks in rats.　Autonomic blockade with atropine, metoprolol, and dual atropine/metoprolol blockade (2 mg/kg) at postnatal day (P) 4 and P12 demonstrated predominantly sympathetic effects on baseline HR. From birth to P9, rats restrained by electrocardiography electrodes for 5 min displayed slow cardiodeceleration, which changed into transient bradycardia (TB) during P9-14. Interestingly, this TB was abolished by autonomic blockade on P12 ; stable tachycardia (18% increase) and unstable HR were observed under parasympathetic and sympathetic blockade, respectively. In addition, HR under dual blockade increased by 25% (p=0.009) after the animals were restrained but not under dual blockade with a 10-fold higher dose. These results suggest that TB is mediated by a complex sympathetic-parasympathetic interaction, which is immature during the vulnerable period and can potentially cause life-threatening cardiac events.
秋田医学会の論文
2013-11-21