[Significance of the liver cell in elimination of cholegraphic agents (author's transl)].

The isolated rat liver is used a model to demonstrate the role of the liver cell in the hepatocellcular elimination of cholegraphic contrast agents. The liver morphology determines the passage of the contrast agent from the liver sinus, into the hepatocyte and out into the bile duct, whereby the entry into the liver cell and its excretion into the bile play the most important role. Our results show that the binding of the cholegraphic agents to the plasma protein causes a delay in the cellular uptake; however, this binding it is important to prevent premature renal excretion. An active carrier-mediated transport mechanism is presumed. Y and Z proteins enhance the cellular uptake, the intracellular transport and the biotransformation of the compounds; the exact mechanism being yet unknown. An active transport mechanism also exists at the site of cellular excretion, the capacity of which limits the amounts and the concentration of the excreted agent in the bile, and which can be inhibited competitively. Knowledge of these pharmacokinetics is important for cholegraphy and its interpretation.