Effect of cisplatin on H + transport by H +-ATPase and Na +/H + exchanger in rat renal brush-border membrane

Abstract

The effect of the potent anticancer drug cisplatin, cis-diamminedichloroplatinum (II) (CDDP), on H +-ATPase and Na +/H + exchanger in rat renal brush-border membrane was examined. To measure H + transport by vacuolar H +-ATPase in renal brush-border membrane vesicles, we employed a detergent-dilution procedure, which can reorientate the catalytic domain of H +-ATPase from an inward-facing configuration to outward-facing one. ATP-driven H + pump activity decreased markedly in brush-border membrane prepared from rats two days after CDDP administration (5 mg/kg, i.p.). In addition, N-ethylmaleimide and bafilomycin A 1 (inhibitors of vacuolar H +-ATPase)-sensitive ATPase activity also decreased in these rats. The decrease in ATP-driven H + pump activity was observed even at day 7 after the administration of CDDP. Suppression of ATP-driven H + pump activity was also observed when brush-border membrane vesicles prepared from normal rats were pretreated with CDDP in vitro. In contrast with H +-ATPase, the activity of Na +/H + exchanger, which was determined by measuring acridine orange fluorescence quenching, was not affected by the administration of CDDP. These results provide new insights into CDDP-induced renal tubular dysfunctions, especially such as proximal tubular acidosis and proteinuria.