Abstract
Summary
Heart rate responses evoked by submaximal and supramaximal electrical stimulation of the right vagus nerves at stimulus frequencies ranging from 5 to 80 cps were determined before and after i.v., infusion of 5 mg/kg of cocaine in vagotomized, open-chest dogs. Comparison of stimulus frequency-heart rate response curves showed that cocaine enhanced the rate of ventricular escape from vagal inhibition at high frequencies of stimulation and opposed the slowing of sinus rate at lower frequencies of stimulation. Cocaine also decreased the incidence and duration of asystole induced by vagal nerve stimulation. The results of this study are consistent with the hypothesis that adrenergic factors may play a prominent role in the phenomenon of vagal escape.
Get full access to this article
View all access options for this article.