Sodium taurocholate increases hydraulic conductivity in rabbit collecting tubule

Abnormalities in renal tubular function occur commonly in the setting of hyperbilirubinemia. In the present studies, the possibility that the bile salt sodium taurocholate exerts a direct effect on renal epithelial transport was investigated in vitro. We found that addition of sodium taurocholate to fluid bathing perfused rabbit cortical collecting tubules increases hydraulic conductivity (Lp) in a manner similar in time course and significantly less in magnitude to that observed with maximal concentrations of arginine vasopressin. Sodium taurocholate reversibly potentiates rabbit cortical collecting tubular Lp stimulated by maximal concentrations of arginine vasopressin and a nonhydrolyzable cyclic AMP analogue. We also found that sodium taurocholate induces a dose-dependent leak from tubular lumen to bathing fluid of a small molecular weight substance (125I-iothalamate). Our studies suggest that sodium taurocholate increases rabbit cortical collecting tubular Lp by a cyclic AMP independent mechanism.