Regulation des renalen Natrium-abhängigen Gallensäuren-Transporters (ASBT) durch Sexualhormone und Glukokortikoide

Abstract

The bile acids filtered through the glomeruli nearly completely escape urinary excretion due to an effecient tubular reabsorption process, which help to conserve bile acids. Reabsorption is mediated by the sodium-dependent bile acid transporter (ASBT) localized in the apical brush border membrane of the proximal tubular cell. The aim of the present study was to assess whether the ASBT-mediated transport of the bile acid taurocholate is regulated by sex hormones or glucocorticoids. In-vitro uptake experiments with freshly isolated proximal tubular cells from female and male sprague-dawley rats and in-vivo clearance experiments were performed using the radioactive bile acid 3H-taurocholate as a substrate. Furthermore, western blot analyse were performed to determine the ASBT-protein amount. The uptake experiments with freshly isolated proximal tubular cells showed a high significant difference of the 3H-taurocholate accumulation ratio of 5.63 +/- 0.28 in male versus 3.68 +/- 0.43 in female animals (p0.05). Western blot analysis could not show a difference of ASBT-protein amount. Thus, we could exclude possible regulation of the ASBT in the proximal tubule