Intrahepatic sources of biliary-like micelles.

To study the hepatocellular origins of biliary lipids, bile acid-lipid micelles were isolated from rat liver subfractions in vitro by Sephadex G-100 column chromatography, using 10 mM sodium taurocholate in the column eluant. Micelles of similar size to biliary micelles were obtained from microsome suspensions and from Golgi content that had been isolated in 5 mM sodium taurocholate-containing subcellular fractionation media. The phospholipid composition of these "biliary-like' micelles was similar but not identical to that of biliary micelles; cholesterol was detected in the micelles from Golgi content but not microsomes. 'Biliary-like' micelles could not be isolated from plasma membranes (including highly purified canalicular membranes), Golgi membranes or liver cytosol. These data suggest that biliary lipid micelles (or micelle precursors) may originate from the endoplasmic reticulum and Golgi apparatus.