AJP - Gastrointestinal and Liver Physiology, Vol 255, Issue 6 745-G751, Copyright © 1988 by American Physiological Society
Biliary secretion of organic anions in the dog: association with defined lipid particles
S. Tazuma, R. L. Barnhart, L. E. Reeve, H. Tokumo and R. T. Holzbach
Research Institute, Cleveland Clinic Foundation, Ohio 44106.
Organic anions have recently been found to partition in vitro into various
biliary lipid particulate species according to their relative
hydrophobicities. To establish the physiological relevance of these
observations, we intravenously injected various radiolabeled organic anions
and assessed the distributions of parent compounds and their metabolites to
lipid particles in canine bile. Partitioning into various biliary lipid
particles was determined by gel permeation chromatography. Relative
hydrophobicities of the various organic anions and their radiolabeled
conjugates were determined by reverse-phase high-pressure liquid
chromatography. A strong positive correlation (P less than 0.001) was found
between percent vesicular association and degree of hydrophobicity for a
given organic anion and/or its more polar conjugate. We conclude that 1)
the hydrophobic-hydrophilic balance of organic anions is a key factor
governing their partitioning to lipid particles secreted in bile; 2) the
present study agrees well with our previously published in vitro
observations; and 3) other chemical constituents, e.g., proteins, mucin,
etc., appear to have little or no effect on organic anion transport in
bile.
