The Influence of Arterial Pressure on the Antihypertensive Action of a Normal Kidney, a Biological Servomechanism

Abstract

Isolated normal kidneys were connected to the circulatory system of rats with renal hypertension. In 11 experiments, the isolated normal kidney was perfused with the full force of the hypertensive levels of blood pressure. In 13 other experiments, a variable resistance in the arterial connection to the isolated kidney allowed us to perfuse the isolated kidney at low normal levels of pressure (85-95 mm Hg). When the normal kidney was perfused with the higher arterial pressure for 2 hours, there was a distinct drop in the arterial pressure of the hypertensive rat to a level 1/3 of the way toward normal. When the normal kidney was perfused at low normal pressures, virtually no drop in the arterial pressure of the hypertensive rat occurred. Apparently the antihypertensive mechanism of a normal kidney behaves appropriately, being brought into action by a high arterial pressure and being held in check by low normal pressures. This would appear to be a feed-back arrangement designed to maintain normal arterial pressures.