CILNIDIPINE ATTENUATES RENAL NERVE STIMULATION-INDUCED RENAL VASOCONSTRICTION AND ANTINATRIURESIS IN ANESTHETIZED DOGS

We examined the effects of cilnidipine, which is an L-and N-type Ca2channel blocker, on adrenergically regulated renal functions in anesth etized dogs. Renal nerve stimulation (RNS) at high frequency (3-7 Hz) decreased renal blood flow (RBF) without changes in systemic blood pre ssure. The RBF response was inhibited by intrarenal arterial (i.r.a.) infusion of cilnidipine at 0.1-0.3 mu g/kg/min. Low-frequency RNS (0.5 -1 Hz) reduced absolute and fractional urinary sodium excretion. These responses were attenuated during i.r.a. infusion of cilnidipine at 0. 3 mu g/kg/min. An increase in norepinephrine secretion rate induced by low-frequency RNS was also attenuated during cilnidipine infusion. Th ese results suggest that cilnidipine can suppress norepinephrine relea se from the renal nerve endings and thereby interfere with the neural control of renal functions.