[Physiology of biliary excretion of roentgenographic contrast media (author's transl)].

Contrast agents for oral and intravenous cholecysto-cholangiography are iodinized lipophilic compounds with marked albumin binding. Their selective uptake by the liver occurs because of the presence of a membrane transport system and preferential binding to the hepatic cytoplasmatic proteins. Peroral contrast agents are conjugated. The canalicular excretion is an active carrier-mediated process limited by a transport maximum. Intravenous contrast agents are potent choleretics. Bile salts are important for intestinal absorption and hepatic excretion of the contrast agents. Pharmacological agents do not improve the biliary excretion of contrast compounds. The value of various investigation techniques is discussed.