Reflex vascular responses to changes in left ventricular pressure in anaesthetized dogs

In dogs anaesthetized with chloralose, changes in left ventricular systolic pressure were induced using a preparation in which the pressure changes did not distend the aortic arch and in which left atrial and carotid sinus pressures were held constant. The systemic circulation was perfused at constant flow and drained from the venae cavae at constant pressure. An increase in left ventricular systolic pressure caused reflex dilatation of systemic resistance and capacitance vessels as indicated by decreases in arterial perfusion pressure and venous outflow. Responses were obtained when ventricular systolic pressure changed between 16 and 28 kPa (120-210 mHg). Responses to changes in ventricular pressure were reduced when the carotid sinuses were perfused at high pressures. These results indicate that changes in pressure in the left ventricle result in reflex changes in vascular resistance and capacitance and that responses are obtained to changes in ventricular pressure over a physiological range.