Changes of depolymerized and polymerized tubulin proteins in the liver after taurocholic acid administration with or without colchicine pretreatment and cholestasis due to cytochalasin B and bile duct ligation in rats

Microtubules, which are components of the cytoskeleton, are the organelles involved in vesicular transport. In the hepatocyte, the microtubular network is presumed to be concerned with bile acid secretion, and there may also be some structural changes in cholestatic conditions. The polymerized tubulin levels were determined as microtubules in the liver by the radiochemical assay in rats after the administration of taurocholic acid, colchicine, taurocholic acid following the treatment of colchicine, cytochalasin B and common bile duct ligation. The polymerized tubulin levels were increased after the high dose administration of taurocholic acid, but were decreased after the treatment with colchicine. In cholestasis models induced by cytochalasin B and common bile duct ligation, the polymerized tubulin levels were markedly increased. These findings suggest the microtubule system plays an important role in the excretion of a large amount of bile acids into the bile, and that growth of the microtubular network occurs in cholestasis in order to promote the vesicular transport and to maintain the cell shape.