AJP - Gastrointestinal and Liver Physiology, Vol 254, Issue 6 819-G823, Copyright © 1988 by American Physiological Society
Effects of cholecystokinin octapeptide on contractile motility of guinea pig common bile duct
T. Takahashi, M. Kusunoki, M. Kantoh, T. Yamamura and J. Utsunomiya
Second Department of Surgery, Hyogo College of Medicine, Japan.
Cholecystokinin octapeptide (CCK-8)-induced contraction and
[3H]acetylcholine ([3H]-ACh) release from the longitudinal muscle strip of
the guinea pig common bile duct were studied by a standard organ bath
method and superfusion system. CCK-8 (10(-7) M) caused a biphasic
contraction, a rapid phasic contraction followed by a fading tonic
contraction. Hexamethonium, propranolol, and phentolamine had no effects on
CCK-8-evoked contraction. Atropine or tetrodotoxin significantly reduced
CCK-8-evoked initial phasic contraction and produced a rightward shift of
the dose-response curve for CCK-8 (10(-10)-3 x 10(-7) M). CCK-8 provoked a
significant [3H]ACh release in a dose-dependent manner, which was almost
completely abolished by tetrodotoxin or Ca2+-free medium. These results
suggest that CCK-8 receptors are present not only on the smooth muscle
cells but also on the intramural cholinergic nerve cell bodies of the
guinea pig common bile duct.
