Hepatocellular transport and secretion of biliary lipids

Bile is the route for elimination of cholesterol from the body. Recent stud ies have begun to elucidate hepatocellular, molecular and physical-chemical mechanisms whereby bile salts stimulate biliary secretion of cholesterol t ogether with phospholipids, which are enriched (up to 95%) in phosphatidylc holines. Active translocation of bile salts and phosphatidylcholines across the hepatocyte's canalicular plasma membrane provides the driving force fo r biliary lipid secretion. This facilitates physical-chemical interactions between detergent-like bile salt molecules and the ectoplasmic leaflet of t he canalicular membrane, which result in biliary secretion of cholesterol a nd phosphatidylcholines as vesicles. Within the hepatocyte, separate molecu lar pathways function to resupply bile salts, phosphatidylcholines and chol esterol to the canalicular membrane for ongoing biliary lipid secretion. Cu rr Opin Lipidol 10:295-302. (C) 1999 Lippincott Williams & Wilkins.