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Gall‐bladder and sphincter of Oddi response to cholecystokinin in the Australian possum
Author(s) -
IANNOS J.,
SACCONE G. T. P.,
BUSHELL M.,
BAKER R. A.,
TOOULI J.
Publication year - 1989
Publication title -
journal of gastroenterology and hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.214
H-Index - 130
eISSN - 1440-1746
pISSN - 0815-9319
DOI - 10.1111/j.1440-1746.1989.tb00853.x
Subject(s) - medicine , gall , sphincter of oddi , cholecystokinin , gallbladder , gastroenterology , general surgery , receptor , botany , biology
The effects of cholecystokinin octapeptide (CCK‐OP) on the gall‐bladder (GB) and sphincter of Oddi (SO) of the Australian brush tailed possum were examined in 45 anaesthetized animals. CCK‐OP (20–640 ng/kg) consistently caused the GB to contract in a dose‐dependent manner (Kruskal Wallis P <0.05). In 20 animals, the same dose range of CCK‐OP produced an excitatory response in the SO, increasing the SO motility index (MI = frequency of contractions x mean peak amplitude) dose‐dependently (Kruskal Wallis P < 0.05). In five animals, an inhibitory response, that is, a decrease in MI, was recorded, with 640 ng/kg of CCK‐OP producing a 50% decrease in MI. In the remaining 20 animals, variable responses of both excitation and inhibition were elicited within the same animal. The action of CCK‐OP on the SO and GB was not modified by atropine, phentolamine or propranolol. Tetrodotoxin (TTX) reversed the inhibitory responses of the SO to CCK‐OP such that responses were excitatory (sign test P <0.05). TTX did not alter the response of the GB to CCK‐OP. It is concluded that CCK‐OP acts directly on smooth muscle receptors of the GB. In the SO, its action is mediated via non‐cholinergic, non‐noradrenergic inhibitory neurons and also by a direct excitatory action on the smooth muscle of the SO.