Vagal and Sympathetic Efferent Discharge in the Bainbridge Reflex of Dogs

A study has been made of the response in vagal and sympathetic cardiac efferentation to i.v. injection, in Bainbridge type experiments on dogs anesthetized with i.v. chloralose. Cardiac vagal efferent activity was recorded from the cervical vagus, and sympathetic cardiac efferentation from the postganglionic cardiac fibres. An increase in sympathetic cardiac discharge, along with diminution in the vagal cardiac discharge, with associated tachycardia, has been detected in the Bainbridge reflex of dogs. A positive linear correlation was observable between the heart rate and the ratio of sympathetic and vagal number of impulses. The acid‐base balance of the experimental animal was controlled.