<原著>ラット毛細胆管側肝細胞膜における胆汁酸の一次性能動輸送について

概要

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ATP-dependent primary active transport of bile acid was studied by using taurocholate, the major bile acid in humans and rats, in vesicles enriched in rat liver canalicular plasma membranes. Incubation of canalicular membrane vesicles with taurocholate in the presence of ATP and magnesium ion (Mg^<2+>), resulted in a stimulated uptake of taurocholate into the vesicles. An increase in the Mg^<2+> concentration from 100 μmol/l to 10 mmol/l in the presence of 1 mmol/l ATP and ATP-regenerating system, caused an increase in the taurocholate uptake to the level of saturation in a concentration dependent manner (Km=400 μmol/l). Replacement of Mg^<2+> with the same concentration of manganese ion, cobalt ion and cadmium ion, caused a decrease in ATP-dependent taurocholate transport to 70%, 38% and 53%, respectively. Other bile acids such as glycocholic acid and taurodeoxycholic acid had dose-dependent inhibitory effects on ATP-dependent active transport of taurocholate, but non-bile acid organic anions such as glutathione and cefpiramide had only weak or no inhibitory effects. Sulfated bile acids such as taurolithoclolic acid 3-O-sulfate inhibited ATP-dependent taurocholate transport competitivelv (Ki=23 μmol/l), which was in contradiction to the hypothesis that serarate transport systems in the rat liver exist for biliary secretion of sulfated and unsulfated bile acids.
近畿大学の論文
1994-03-25