Effect of some antihypertensive drugs and catecholamine depletors on the plasma renin activity in the rat.

The effect of some antihypertensive drugs and catecholamine depletors on the plasma renin activity (PRA) has been investigated in the rat. Diazoxide and CIBA 4416-Go. increased and clonidine decreased the PRA significantly. The increase in PRA following diazoxide was partially blocked by oxprenolol, adrenalectomy and demedullation. Adrenal cortex does not seem to contribute to this increase in PRA following diazoxide. Pretreatment of rats with reserpine, guanethidine or 6-hydroxydopamine alsine, guanethidine and 6-hydroxydopamine when given acutely or repeatedly (for 3 days) did not produce any significant change in PRA. It is concluded that vasodilators like diazoxide and CIBA 4416-Go. increase PRA resulting from sympathetic activation which follows hypotension; this increase is blocked by catecholamine depletors like reserpine, guantethidine and 6-hydroxydopamine.