Intracellular Transport of Small Hydrophobic Compounds by the Hepatocyte

ABSTRACT

The liver is responsible for the detoxification and biliary excretion of a variety of endogenous andxeno-biotic compounds and, therefore, is capable of responding to rapid fluctuations in metabolic demand. In order to accomplish this function, the hepatocyte must efficiently transport a host of substrates with wide-ranging physical-chemical properties to intracellular sites for biotransformation and subsequent secretion into the bile. The trafficking of substrates and metabolites within the liver cell is a complex process, involving the coordinated action of cellular proteins, organellar membranes, the cytoskeleton, vesicular transport pathways, and bulk convective cytoplasmic flow. This review summarizes recent developments in the field of intracellular transport, with particular reference to the metabolism of small hydrophobic and amphipathic molecular species (e.g., bilirubin, bile salts, fatty acids) by the hepatocyte.

KEY WORDS

biological transport - diffusion - carrier proteins - cell membranes - cytoplasmic streaming - cytoskeleton