Bidirectional transport of cholesterol between gallbladder
epithelial cells and model bile.
Hayashi, Alex, Sum P. Lee.
Department of Medicine, VA Medical Center and University of
Washington School of Medicine, Seattle, Washington
APStracts 3:0074G, 1996.
Lipids in hepatic bile may be modified by the gallbladder epithelium.
The purpose of this study is to demonstrate a bi-directional exchange
of cholesterol between biliary lipid carriers and gallbladder
epithelial cells and to determine the factors regulating this
cholesterol transfer. Gallbladder epithelial cells were cultured to
confluent monolayers, their membranes labelled with endogenously
synthesized [14C] cholesterol, and the cells were incubated with
model bile introduced into the apical membrane compartment.
Similarly, model bile with different lipid composition containing
[3H] cholesterol was incubated with the unlabelled monolayers. We
found that cholesterol in the apical membrane bilayer of the
epithelial cells exchanged readily with that in bile, but only in the
presence of bile salts. The rate of exchange is dependent on the
concentration and species of bile salts. The net gain of cholesterol
(absorption) or net loss of cholesterol (cytotoxicity) exhibited by
the epithelial cells was regulated by the thermodynamic stability of
cholesterol and the detergent effect of mixed micelles in bile. It is
also possible that the physicochemical composition of lipids in bile
may modify the cellular function of the gallbladder epithelium.
Received 24 August 1994; accepted in final form 9 March 1996.
APS Manuscript Number G316-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96