The role of the canalicular multispecific organic anion transporter in the disposal of endo- and xenobiotics.

Bile is an important excretory route for the elimination of amphiphilic organic anions, and hepatocytes are the primary secretory units of bile formation. The hepatocytic basolateral and canalicular membranes are equipped with various carrier proteins. Transport across the canalicular membrane represents a major concentrative step. Various ATP-dependent transporters have been identified, such as a multispecific organic anion transporter (canalicular multispecific organic ion transporter, cMOAT), a bile acid transporter and several P-glycoproteins. TR- rats, which lack cMOAT activity, have been valuable in defining the substrate specificity of cMOAT. A wide range of glucuronide-, glutathione- and sulfate-conjugates are transported by this system.