Cholecystokinin-induced contraction of opossum sphincter of Oddi. Mechanism of action.
In this study, we evaluated the mechanism of action whereby cholecystokinin increases spike-burst rate of the opossum sphincter of Oddi (SO). Each spike burst corresponds to a peristaltic SO contraction. Two types of animal preparations were evaluated: (1) awake chronic animal preparations and (2) anesthetized animals. A total of 19 chronic animals were prepared by implantation of electrodes on the SO, gastric antrum, duodenum, and jejunum. SO spike-burst rate was stimulated by intravenous infusion of CCK-OP (10 ng/kg/min), feeding, or intraduodenal infusion of fat-containing nutrient. Each stimulus was begun 20 min after cessation of phase III duodenal MMC activity and caused an increase in SO spike-burst rate from about 2 to 6/min that lasted for less than or equal to 1 hr. Such increases were antagonized substantially by hexamethonium, atropine, or methysergide. The CCK antagonist, L364718, antagonized the excitatory SO response to CCK-OP infusion or intraduodenal infusion of fat-containing nutrient (Isocal) but did not antagonize the response to feeding; CR1409 had no antagonistic effect on SO response to any of the three types of stimuli. In the acute studies in anesthetized animals, an intravenous bolus dose of CCK-OP (800 ng/kg) caused a substantial increase in SO spike-burst rate that was antagonized by CR1409 but not by atropine, hexamethonium, methysergide, L364718, or TTX.(ABSTRACT TRUNCATED AT 250 WORDS)
Hanyu
N
N
Department of Radiology, Medical College of Wisconsin, Milwaukee 53226.
Dodds
W J
WJ
Layman
R D
RD
Hogan
W J
WJ
D014670:Ampulla of Vater / Q000187:drug effects*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001285:Atropine / Q000494:pharmacology; D001570:Benzodiazepinones / Q000494:pharmacology; D002766:Cholecystokinin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D020109:Devazepide; D004567:Electrodes, Implanted; D005502:Food; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D007262:Infusions, Intravenous; D008784:Methysergide / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009893:Opossums / Q000502:physiology*; D009803:Sphincter of Oddi / Q000187:drug effects*
D000959:Antihypertensive Agents; D001570:Benzodiazepinones; D006584:Hexamethonium Compounds; D018738:Hexamethonium; D001285:Atropine; D002766:Cholecystokinin; D020109:Devazepide; D008784:Methysergide