AJP - Gastrointestinal and Liver Physiology, Vol 245, Issue 1 157-G163, Copyright © 1983 by American Physiological Society
Pharmacological and physiological doses of insulin and determinants of bile flow in dogs
C. A. Garberoglio, H. M. Richter 3rd, A. Henarejos, A. R. Moossa and A. L. Baker
The role of insulin in control of bile secretion is uncertain. To study the
mechanism of choleresis produced by large doses of insulin, bile was
collected through modified Thomas cannulas from dogs anesthetized with
pentobarbital. Animals received pipenzolate methylbromide, sodium
taurocholate, and [14C]erythritol. After bile flow had stabilized three
animals received infusions of insulin at 2, 4, 13, 26, 35, and 70 mU . kg-1
. min-1 for 40 min each. Bile and [14C]erythritol clearance increased (P
less than 0.005), but bile salt output remained constant, suggesting that
the choleresis was mainly due to enhanced bile salt-independent canalicular
flow. Plasma insulin and glucagon levels also rose when insulin was
infused. To exclude the possible effects of glucagon three additional
animals received somatostatin (800 ng . kg-1 . min-1) along with infusions
of insulin. Bile flow and [14C]erythritol clearance again increased
significantly, but glucagon levels remained low, suggesting that the
effects on bile flow were due to insulin alone. To determine whether
physiological doses of insulin altered bile flow dogs were anesthetized
with pentobarbital and received pipenzolate methylbromide, taurocholate,
[14C]erythritol, and somatostatin (800 ng . kg-1 . min-1). Insulin (0.2 and
0.8 mU . kg-1 . min-1) was infused through the portal vein for 1 h each.
Bile flow and [14C]erythritol clearance increased with insulin (0.8 mU .
kg-1 . min-1; P less than 0.02), suggesting that the choleresis may have
been due to bile salt-independent canalicular flow. Plasma insulin rose to
physiological postprandial levels. These studies demonstrate that
pharmacological and physiological levels of insulin administered to dogs
produce a significant choleresis. Thus insulin may play an important role
in the regulation of bile secretion.
