Hemodynamic changes induced by reversal of early and late renovascular hypertension.

The hemodynamic changes associated with reversal of Goldblatt two-kidney, one-clip hypertension in conscious rats were studied using radioactive microspheres. In both the early phase (less than 6 wk from clipping) when plasma renin was elevated and the chronic phase (greater than 4 mo) when plasma renin was normal, hypertension was maintained by elevated peripheral resistance. Unclipping or removal of the ischemic kidney normalized blood pressure within 24 h by reduction in peripheral resistance. In early-phase hypertension blood pressure remained normal at 60 days after nephrectomy or unclipping, but in chronic-phase hypertension blood pressure was significantly elevated at 60 days after nephrectomy despite a similar fall in peripheral resistance. Plasma renin fell to normal or subnormal values after reversal in both early and chronic hypertension. Thus reversal of hypertension is associated with a rapid reduction in peripheral resistance even in longstanding hypertension. Since removal of the ischemic kidney and unclipping were equally effective, reversal must depend on either inhibition of a pressor system derived from the ischemic kidney or activation of a peripheral vasodepressor system not dependent on a revascularized kidney.