Effect of organic anions on acyl chain composition of secreted biliary lecithin in rats: relation to hepatocellular vesicle pathway

Abstract

Organic anions can uncouple bile salt secretion from the secretion of phospholipid and cholesterol. The uncoupling mechanism appears to be dependent on the type of anion present. To investigate the effect that different uncoupling mechanisms may have on the flow of bile and its composition, rats were depleted of bile salt pool by overnight biliary diversion and reinfused intravenously with sodium taurocholate (STC) at a constant rate (160 nmol/min per 100 g b.w.). After bile salt secretion had achieved a steady state, sulfobromophthalein (BSP) or papaverine was continuously administered at a rate of 100 nmol/min per 100 g b.w. with STC. During the intravenous infusion of BSP or papaverine, the output of biliary lecithin and cholesterol decreased without affecting bile salt output. The degree of fatty acyl chain saturation in biliary lecithin was increased by BSP infusion and decreased by papaverine infusion. The mechanism by which bile salt secretion is uncoupled from the secretion of phospholipid and cholesterol affects the acyl chain composition of secreted lecithin. The changes in composition of lecithin acyl chains may reflect the intervention by different anions at different points in the lipid transport pathway.