QUANTITATIVE OBSERVATIONS ON THE EXTRA-VAGAL COMPONENT OF CAROTID SINUS PRESSORECEPTIVE CARDIAC RESTRAINT

Abstract

The extra-vagal component (sympathetic and humoral) of carotid pressoreceptive chronotropic cardiac restraint was studied quantitatively in dogs anesthetized with morphine and urethane. Major secondary factors were controlled by means of carotid body exclusion (embolization), constant aortic blood pressure and pulmonary ventilation and total vago-sympathetic-aortic denervation. The curve relating endosinual pressure and extra-vagal heart slowing by a single carotid sinus was sigmoid, and parallel with those relating endosinual pressure to total (vagi intact) cardiac slowing, vascular depression and respiratory depression. The maximal slowing was approximately 8%.