Effects of 5-hydroxytryptamine and morphine on the stomach motility in situ.
The effects of 5-hydroxytryptamine and morphine on the stomach motility were determined in in situ experiments. 5-Hydroxytryptamine and morphine inhibited stomach motility of unanaesthetized cats but did produce a slight contraction of the stomach of anaesthetized cats. In unanaesthetized rabbits, 5-hydroxytryptamine caused a contraction, followed by an inhibition of motility, and morphine depressed motility. The 5-hydroxytryptamine-induced contraction is a direct action on smooth muscle and the inhibition of spontaneous movement due to 5-hydroxytryptamine may be, in part, mediated through catecholamine-release and in part, result from paralysis of the receptors for 5-hydroxytryptamine in the cholinergic nerves in the stomach. In anaesthetized rabbits, 5-hydroxytryptamine produced contraction and morphine had no effect. In unanaesthetized guinea pigs, 5-hydroxytryptamine caused a contraction and morphine abolished spontaneous movement of the stomach. In anaestetized guinea-pigs, 5-hydroxytryptamine caused contraction and morphine produced no effect. The 5-hydroxytryptamine-induced contraction of the guinea pig stomach is indirect. From these results it is concluded that the differences in the modes of actions of 5-hydroxytryptamine and morphine on gastric motility are related to differences in species and experimental conditions such as anaesthesia.
D000109:Acetylcholine / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D002415:Cats; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D006168:Guinea Pigs; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010424:Pentobarbital / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology*; D013045:Species Specificity; D013997:Time Factors
D012701:Serotonin; D009020:Morphine; D011433:Propranolol; D010424:Pentobarbital; D000109:Acetylcholine; D004837:Epinephrine; D010646:Phentolamine