ARTERIAL COMPLIANCE AND ITS CONTROL BY THE BAROREFLEX IN HYPERTENSIVEDOGS

The effect of the carotid baroreflex on systemic arterial compliance w as tested in normotensive and Goldblatt hypertensive dogs. After the d evelopment of experimental hypertension, dogs were acutely anesthetize d with pentobarbital sodium and vagotomized. The carotid sinuses were then isolated and held at controlled carotid sinus pressures (CSP) of 50, 125, and 200 mmHg. The dogs were placed on constant flow, constant venous pressure, cardiopulmonary bypass. Arterial compliance was dete rmined from the time constant of the exponential fall in arterial pres sure, which occurred when the flow was stopped at three different leve ls of CSP. The reflex characteristic curve (mean arterial pressure vs. CSP) was shifted upward and to the right in the hypertensive group. A rterial compliance significantly decreased with decreasing CSP, but at any given level of CSP, arterial compliance was not different in the normotensive and hypertensive groups. A non-linear analysis revealed t hat the arterial compliance-arterial pressure relationship was not alt ered by Goldblatt experimental hypertension. The results of this study indicate that the arterial compliance is primarily a function of the absolute level of arterial pressure. Baroreflex control of arterial co mpliance is important at lower levels of arterial pressure.