PERIPHERAL VASCULAR RESPONSES TO CHANGES IN LEFT VENTRICULAR PRESSURE IN ANAESTHETIZED DOGS

¹ Department of Cardiovascular Studies, University of Leeds, Leeds LS2 9JT

In dogs anaesthetized with chloralose, cardiac receptors were stimulated by increases in left ventricular systolic pressure effected by changes in aortic root pressure. Left atrial and carotid sinus pressures were controlled. A large step increase in ventricular pressure resulted in transient decreases in heart rate, systemic arterial perfusion pressure and perfusion pressure to a vascularly isolated hind limb. The magnitudes of these responses were about three-quarters of those to either a large change in carotid sinus pressure or aortic root injection of 20 µg veratridine. Steady-state responses were smaller. There was no significant change in perfusion pressure to a perfused cutaneous vein. Graded changes in ventricular systolic pressure showed that the most sensitive pressure range was between 20 and 24 kPa. These results indicate that changes in left ventricular pressure result in significant vasodilation in the hind limb and in other regions and that responses are obtained when the pressure is moderately elevated.