title: Effects of C-terminal octapeptide of cholecystokinin and prostaglandins on adrenergic functions in the guinea-pig gallbladder and sphincter of Oddi.
abstract: Effects of C-terminal octapeptide of cholecystokinin (C8-CCK) and prostaglandins E1, E2 and E alpha on noradrenaline-induced responses and 3H-noradrenaline release in the gallbladder and sphincter of Oddi of guinea pigs were examined. In the sphincter of Oddi, noradrenaline in low concentrations induced a relaxation which was blocked by either phentolamine or propranolol, while noradrenaline in high concentrations induced a contraction which was blocked by phentolamine. These results suggest the existence of excitatory and inhibitory alpha-receptors and inhibitory beta-receptors in the sphincter of Oddi. In the gallbladder, the adrenergic receptors are alpha-excitatory and beta-inhibitory. C8-CCK (10(-9) g/ml) potentiated both contractile and relaxing responses to noradrenaline, in the gallbladder. The same concentration of prostaglandins potentiated only contractile response to noradrenaline. In the sphincter of Oddi, noradrenaline-induced responses were not affected by C8-CCK and prostaglandins. Prostaglandins inhibited 3H-efflux evoked by electrical stimulation, while C8-CCK had no effect on the 3H-efflux from both preparations. These results suggest that C8-CCK enhances the contractile and relaxing responses to noradrenaline, and that prostaglandins act in a similar way on the postsynaptic response and, in addition, inhibit presynaptically the release of noradrenaline in the gallbladder. In the sphincter of Oddi, only prostaglandins inhibit the presynaptic event.
mesh_terms: D014670:Ampulla of Vater / Q000294:innervation*; D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology*; D005260:Female; D005704:Gallbladder / Q000187:drug effects / Q000294:innervation*; D006168:Guinea Pigs; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D011453:Prostaglandins / Q000494:pharmacology*; D011941:Receptors, Adrenergic / Q000187:drug effects; D009803:Sphincter of Oddi / Q000187:drug effects / Q000294:innervation*; D013564:Sympathetic Nervous System / Q000187:drug effects*
chemical_list: D009842:Oligopeptides; D011453:Prostaglandins; D011941:Receptors, Adrenergic; D002766:Cholecystokinin; D009638:Norepinephrine