AJP - Gastrointestinal and Liver Physiology, Vol 251, Issue 4 431-G435, Copyright © 1986 by American Physiological Society
Greater taurodeoxycholate biotransformation during backward perfusion of rat liver
U. Baumgartner, K. Miyai and W. G. Hardison
Differing patterns of taurodeoxycholate (TDC) metabolism and biliary
excretion were studied with a forward-and-backward perfusion model of the
isolated rat liver. Livers were perfused with 8 microM TDC via either the
portal vein (forward) or the hepatic vein (backward). Bile was collected,
total bile acids measured enzymatically, and bile composition determined by
high-pressure liquid chromatography and thin-layer chromatography. During
backward perfusion 48% of infused TDC was metabolized to taurocholate (TC)
and 22.0% to other minor TDC metabolites. During forward perfusion,
however, only 16% of administered TDC was metabolized to TC and 6.5% to
minor metabolites. Total bile acid output was similar for both forward and
backward perfusions. The kinetics of biliary bile acid excretion also
differed between forward and backward perfusion. The time necessary for 50%
excretion of labeled TDC and its metabolites was 3.5 +/- 0.45 min during
forward and 18 +/- 3.50 min during backward perfusion, a time difference of
14.5 min. The greater biotransformation of TDC during backward perfusion
could be explained by its longer intracellular residence. The reason for
the delayed excretion of TDC during backward perfusion is unknown.
