Electrophysiologic Response to Autonomic Receptor Stimulation of Pertussis Toxin Rreated Canimc Cardiac Muscle.

提示自主神经控制异常可能是百日咳疫苗接种后婴儿猝死的原因之一。百日咳毒素对心肌的生化效应表现为对儿茶酚胺的反应增强，对乙酰胆碱的反应降低。本研究旨在阐明百日咳毒素对犬浦肯野纤维自主神经受体刺激的增龄性电生理效应。在百日咳毒素处理的成年纤维中，异丙肾上腺素的正性变时性作用增强，而乙酰胆碱的负性变时性作用减弱。与成人纤维相比，新生儿纤维对自律性的影响较小。在百日咳毒素处理的新生纤维中，异丙肾上腺素引起的正性肌力作用没有增强。异丙肾上腺素对新生浦肯野纤维的肾上腺素能刺激不被神经末梢吸收，对自律性的影响较小。这可能部分是由于与年龄相关的GTP结合蛋白或β肾上腺素能受体的差异。

It is proposed that abnormal autonomic control may play a role in sudden death of infants received pertussis vaccination. The biochemical effect of pertussis toxin on cardiac muscle has been shown as an increased response to catecholamines and decreased response to acetylcholine. The purpose of this study is to clarify the age related electrophysiologic effect of pertussis toxin on canine Purkinje fiber in a response to autonomic receptor stimulation.In pertussis toxin treated adult fibers isoproterenol induced positive chronotropic effect was enhanced, and acetylcholine induced negative chronotropic effect was diminished. Neonatal fiber demonstrated a less effect of isoproterenol on automatisity than adult fiber. In pertussis toxin treated neonatal fibers isoproterenol induced positive inotropic effect was not enhanced.Beta adrenergic stimulation of neonatal Purkinje fiber by isoproterenol which is not absorbed by the nerve ending, has a less effect on automaticity. This may partly due to an age related difference of GTP binding protein or beta adrenergic receptor.