Beneficial effects of verapamil on postischemic renal failure

The effects of calcium blockade with verapamil on postischemic renal failure were tested in dogs. Two experiments were performed. In experiment 1 (n = 7), one kidney in each dog received an infusion of verapamil and the other received saline for 30 minutes prior to induction of 1 hour of ischemia. Inulin clearance (CIN), urine flow, and renal blood flow (RBF) were measured. Infusion of verapamil increased urine flow from 0.99 to 4.29 ml/min (P less than 0.001). CIN and RBF did not change significantly nor did urine flow in the saline-treated kidney. Three hours after ischemia there was no significant difference in CIN, although it was lower in verapamil-treated kidneys. RBF declined in both treatments. In experiment 2 (n = 6) kidneys were treated with verapamil and saline for 50 minutes beginning immediately after 1 hour of ischemia. Urine flow and CIN were significantly higher in verapamil-treated kidneys during the infusion (3.09 +/- 0.44 versus 0.26 +/- 0.12 ml/min, P less than 0.001; 28.6 +/- 7 .4 versus 6.2 +/- 3.1 ml/min, P less than 0.025, respectively). CIN remained elevated in verapamil-treated kidneys at 3 hours, however RBF was depressed in both verapamil- and saline-treated kidneys. These results suggest that verapamil is a potent diuretic and that verapamil can be given after renal ischemia with significant attenuation of postischemic renal failure.