Modifications in proximal tubular function induced by nitrendipine in a rat model of acute ischemic renal failure

Calcium channel blockers have been reported to preserve renal function when given prophylactically in animal models of acute renal failure (ARF), but the mechanism by which this effect occurs is unknown. We report that nitrendipine (NTR) ameliorates the decline in endogenous creatinine clearance when administered before to clamp-induced ischemia in rats (NTR + clamp, 0.21 +/- 0.06 ml/min; clamp alone, 0.13 +/- 0.04 ml/min, p less than 0.05). To determine whether this protective effect involves the proximal tubule, we compared the uptake of phosphate by brush border membrane (BBM) vesicles in NTR-pretreated ARF rats and in ARF rats pretreated with vehicle alone. A comparison of vehicle-pretreated/sham-operated and vehicle-pretreated/ARF rats served as a control. The initial uphill phase of Na+ gradient-dependent phosphate transport was significantly greater in NTR/ARF rats as compared with vehicle/ARF rats. Pretreatment with NTR did not affect BBM transport of D-glucose or proline. We conclude that NTR has a modest protective effect on overall renal function, and that preservation of proximal tubular function is probably part of this effect.