Abstract
Verapamil, $Ca^{2+}$-channel blocker, when given into vein or into carotid artery, produced the decrease of urine flow accompanied with the decreased amounts of Na$^{+}$ and $K^{+}$ excreted in urine ($E_{Na}, E_{K}$) and with the decreased clearances of free water (C$_{H_2O}$) and osmolar substance (C$_{osm}$), and then increased reabsorption of Na$^{+}$ and $K^{+}$ in renal tubules (R$_{Na}$, R$_{N}$), glomeruler filtration rate (GFR) and renal plasma flow (RPF) were inhibited when verapamil was given into carotid artery, but were only tendency of reduction when given intravenously. Verapamil, when infused into a renal artery, exhibited diuresis accompanied with the increased GER, RPF, E$_{Na}$ and E$_{K}$, with the decreased filtration fraction (FF) in only infused kidney. At the same time, $C_{H_2O}$ was not changed, R$_{Na}$ and R$_{K}$ were reduced. Antidiuretic action by verapamil administered into vein or into carotid artery in normal kidney was reversed to diuretic action in denervated kidney. At this time, parameters of renal function exhibited the opposite phenomena compared to that elicited by verapamil in normal kidney, wherease renal denervation did not influence the action of verapamil infused into a renal artery. Above results suggest that verapamil produce both antidiuresis through nervous system centrally, not endogenous substances and diuresis by direct action in the kidney. Diurectic action are caused by hemodynamic improvement through dilatioon of vas efferense and by greatly inhibited reabsorption of electrolytes in distal tubules.