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

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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.