Effects of Adrenal Steroid Withdrawal on Chronic Renovascular Hypertension in Adrenalectomized Sheep

¹ Howard Florey Laboratories of Experimental Physiology, University of Melbourne, Parkville, 3052, Victoria, Australia

Adrenalectomized sheep with a single kidney were maintained chronically hypertensive after renal arterial constriction on a maintenance dosage of desoxycorticosterone acetate and cortisone acetate. This level of steroid support is totally without pressor effects in adrenalectomized animals with normal kidneys. Blood pressure was monitored after steroid withdrawal with (1) no replacement of Na⁺ loss, (2) intravenous replacement of Na⁺ loss, (3) withdrawal of one steroid alone. When cortisone alone was withdrawn, the plasma [Na ⁺] and [K⁺] remained within normal limits, no natriuresis occurred, and the blood pressure remained elevated. When both steroids, or DOCA alone, were withdrawn, a profound natriuresis and alteration in plasma ionic concentrations occurred; the blood pressure, however, remained persistently elevated above the values obtained before renal arterial constriction despite clinical and biochemical evidence of adrenoprival status. This pattern of blood pressure response compared with that following release of the constriction is interpreted as evidence against a causative role for the adrenal cortex in the mechanism of renovascular hypertension.

Accepted on October 24, 1968