AJP - Gastrointestinal and Liver Physiology, Vol 246, Issue 1 67-G71, Copyright © 1984 by American Physiological Society
Differing effects of norcholate and cholate on bile flow and biliary lipid secretion in the rat
E. R. O'Maille, S. V. Kozmary, A. F. Hofmann and D. Gurantz
The effects of norcholate (a C23 bile acid that differs from cholate in
having a side chain containing four rather than five carbon atoms) on bile
flow and biliary lipid secretion were compared with those of cholate, using
the anesthetized rat with a bile fistula. Norcholate and cholate were
infused intravenously over the range of 0.6-6.0 mumol X min-1 X kg-1. Both
bile acids were quantitatively secreted into bile; norcholate was secreted
predominantly in unconjugated form in contrast to cholate, which was
secreted predominantly as its taurine or glycine conjugates. The increase
in bile flow per unit increase in bile acid secretion induced by norcholate
infusion [17 +/- 3.2 (SD) microliters/mumol, n = 8] was much greater than
that induced by cholate infusion (8.6 +/- 0.9 microliters/mumol, n = 9) (P
less than 0.001). Both bile acids induced phospholipid and cholesterol
secretion. For an increase in bile acid secretion (above control values) of
1 mumol X min-1 X kg-1, the increases in phospholipid secretion [0.052 +/-
0.024 (SD) mumol X min-1 X kg-1, n = 9] and cholesterol secretion (0.0071
+/- 0.0033 mumol X min-1 X kg-1, n = 9) induced by norcholate infusion were
much less than those induced by cholate infusion (0.197 +/- 0.05 mumol X
min-1 X kg-1, n = 9, and 0.024 +/- 0.011 mumol X min-1 X kg-1, n = 9,
respectively; P less than 0.001 for both phospholipid and cholesterol). The
strikingly different effects of norcholate on bile flow and biliary lipid
secretion were attributed mainly to its possessing a considerably higher
critical micellar concentration than cholate.
