FRACTIONATION OF LIVERS FOLLOWING DIOSGENIN TREATMENT TO ELEVATE BILIARY CHOLESTEROL

The plant saponin, diosgenin, is known to induce a marked increase in biliary cholesterol/phospholipid ratio. We reasoned that putative bili ary lipid supply vesicles might be similarly enriched with cholesterol . Seven-day diosgenin feeding to rats resulted in significantly increa sed biliary cholesterol and cholesterol/phospholipid ratio, but had no effect on total cholesterol or phospholipid content of the liver. Sub cellular fractionation of livers showed no selective increase in any f raction (nuclear, mitochondrial, lysosomal, microsomal) of the homogen ate. Further subfractionation of microsomal or nuclear (plasma membran e) fractions also showed no difference between control and diosgenin g roups. Thus, no intracellular vesicle fraction has been identified wit h the provision of the enhanced biliary cholesterol and the results ar e discussed in terms of the possible involvement of cytosolic lipid-bi nding proteins as putative lipid carriers to the canalicular membrane as an alternative to the presence of the lipid in lipid supply vesicle s.