Effect of nicardipine on the relationship of renal blood flow and of renal vascular resistance to perfusion pressure in dog kidney.

The effect of nicardipine, a Ca channel blocker, on autoregulation of renal blood flow and perfusion pressure-vascular resistance relationship has been investigated in perfused kidneys of anaesthetized dogs. In control animals excellent autoregulation of renal blood flow and pressure-dependent elevation of vascular resistance were observed above 100 mmHg of perfusion pressure. However, intra-arterial infusion of nicardipine at doses of 3 and 10 micrograms min-1 showed dose-dependent impairment of the autoregulatory response and of elevation of vascular resistance. Infusion of nicardipine (2.5 micrograms min-1) into the renal artery also inhibited renal vasoconstriction induced by YC-170, a Ca channel activator. These results suggest that the inhibitory effect of nicardipine upon renal autoregulation may be due to its Ca2+ channel blocking action.