Action of cholecystokinin on the dog sphincter of Oddi: influence of anti-cholinergic agents.
Effects of cholecystokinin (CCK) on bile flow through the sphincter of Oddi (SO) were studied in anaesthetized dogs. Intravenous injection of CCK (0.25, 0.5, 1 and 2 IDU/Kg) elicited a dose-dependent reduction in flow through the SO in the first minutes after CCK administration. Pirenzepine and atropine decreased significantly (P less than 0.05) by 29% and a 40% respectively the inhibitory effect induced by 1 IDU/Kg of CCK, whereas hexamethonium elicited an increase in the inhibitory effect induced by 0.5 IDU/Kg of CCK (P less than 0.05). Intravenous infusion of cummulative doses of CCK had different effects according to the dose infused. Lower doses (0.025 and 0.05 IDU/Kg/min) increased transphincteric flow, however, high doses (0.1, 0.2 and 0.4 IDU/Kg/min) were inhibitory. These finding indicated that CCK had two effects on the SO : firstly, a contractile effect, probably mediated through a direct myogenic action and neuronal release of ACh, and secondly a relaxant effect, probably mediated by stimulation of inhibitory postganglionic neurons.
Pozo
M J
MJ
Department of Physiology, Faculty of Veterinary Sciences, University of Extremadura, Cáceres, Spain.
Salido
G M
GM
Madrid
J A
JA
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001646:Bile / Q000502:physiology; D002766:Cholecystokinin / Q000008:administration & dosage / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D010276:Parasympatholytics / Q000494:pharmacology*; D010890:Pirenzepine / Q000494:pharmacology; D009803:Sphincter of Oddi / Q000187:drug effects / Q000502:physiology*
D006584:Hexamethonium Compounds; D010276:Parasympatholytics; D018738:Hexamethonium; D010890:Pirenzepine; D001285:Atropine; D002766:Cholecystokinin