The Hepatic Uptake Process: Its Implications for Bilirubin Transport

Abstract

One of the fundamental aims of this symposium is to provide a framework upon which information concerning the handling of bilirubin can be knitted together, a framework which will prove useful both to the investigator concerned with fundamental phenomena and the clinician concerned with the care of a patient with jaundice. My task, within this framework, is to provide some insight into the kinetic processes involved in the uptake by the liver of substances like bilirubin. In order to attain this end I will present to you a general examination of the process of uptake at the hepatic cell surface. From this background, I will develop ideas concerning the manner in which the processes of biliary secretion or intracellular metabolic sequestration create steady state concentration gradients in the parenchymal cells distributed along the length of the sinusoids within each liver lobule. Finally, I will deal with the manner in which the lobular gradient phenomenon may account for the increase in the Tm for the biliary secretion of bilirubin which accompanies bile salt induced increments in bile flow.