Hepatic Bile Formation: Bile acid transport and water flow in the canalicular conduit.

Hepatic Bile Formation: Bile acid transport and water flow in the canalicular conduit. Am J Physiol Gastrointest Liver Physiol. 2020 Sep 16;: Authors: Javitt NB Abstract Advances in molecular biology that identified the many carrier-mediated organic anion transporters and advances in microscopy that have provided a more detailed anatomy of the canalicular conduit provide for an updating of the concept of osmotically determined canalicular flow. For the most part water flow is not trans-membrane but via specific pore proteins in both the hepatocyte and the tight junction. These pores independently regulate the rate at which water flows in response to and osmotic gradient and therefore are determinants of canalicular bile acid concentration. Review of the literature indicates that the initial effect on hepatic bile flow of cholestatic agents such as Thorazine and estradiol 17b-glucuronide are on water flow and not BSEP- mediated bile acid transport provides new approaches to the pathogenesis of drug-induced liver injury. Attaining a micellar concentration of bile acids in the canaliculus is essential to the formation of cholesterol-lecithin vesicles, which mostly occur in the peri-portal region of the canalicular conduit. The other regions, mid- and peri-central, may transport lesser amounts of bile acid but augment water flow. By broadening the concept of how hepatic bile flow is initiated, a better understanding of the pathogenesis o...
Source: American Journal of Physiology. Gastrointestinal and Liver Physiology - Category: Physiology Authors: Tags: Am J Physiol Gastrointest Liver Physiol Source Type: research