title: Effect of cholecystokinin-octapeptide on lower esophageal sphincter.
abstract: The effect of cholecystokinin-octapeptide (CCK-OP) on the lower esophageal sphincter (LES) was studied in 50 cats in vivo. CCK-OP caused a dose-dependent fall in LES pressures in all but 4 animals. Maximal sphincter relaxation was obtained with 200 to 400 ng of CCK-OP per kg of body weight. Atropine sulfate and/or hexamethonium, or adrenergic blocking agents (phentolamine or propranolol), in doses that completely inhibit the action of maximal doses of their respective agonists, failed to block the CCK-OP effect. Tetrodotoxin, however, in doses that denervates the LES, antagonized the CCK-OP-induced sphincter relaxation. In these tetrodotoxin-treated animals, CCK-OP produced LES contraction similar to that observed after pentagastrin. These results suggest that CCK-OP stimulates the postganglionic nonadrenergic, noncholinergic inhibitory neurons responsible for sphincter relaxation. CCK-OP also stimulates the circular muscle by direct action causing LES contraction. The latter becomes apparent when the innervation of the LES is abolished by tetrodoxtin.
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001338:Autonomic Fibers, Postganglionic / Q000187:drug effects; D002415:Cats; D002766:Cholecystokinin / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004943:Esophagogastric Junction / Q000187:drug effects* / Q000294:innervation; D005260:Female; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D008365:Manometry; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D010455:Peptides / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013268:Stimulation, Chemical; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D006584:Hexamethonium Compounds; D010455:Peptides; D013779:Tetrodotoxin; D001285:Atropine; D002766:Cholecystokinin; D011433:Propranolol; D010646:Phentolamine