Reflex Inhibition of Heart Rate and Efferent Cardiac Sympathetic Outflow Induced by Colorectal Distension in Anesthetized Rats

Abstract

Colorectal distensions of 60 and 80 mmHg significantly reduced heart rate (HR) and cardiac sympathetic nerve activity in anesthetized rats. This bradycardiac response was not influenced by the intravenous administration of atropine, but was abolished by propranolol, suggesting that it was elicited by sympathetic but not vagal efferent nerves.