The action of prostaglandin E2 on the rhythmic activity of circular muscle of the isolated guinea-pig ileum.
Activity of the circular muscle of the isolated guinea-pig ileum in response to prostaglandin E2 (PGE2), acetylcholine (Ach), 5-hydroxytryptamine (5-HT) and dimethylphenylpiperazinium (DMPP) was investigated. PGE2 produced concentration-dependent rhythmic contractions of the circular muscle superimposed on an increased tone. Ach, 5-HT and DMPP also produced rhythmic contractions of the ileal circular muscle. Small amounts of PGE2 potentiated the rhythmic contractions elicited by Ach. On the other hand, physostigmine markedly potentiated the contractile effect of PGE2. Tetrodotoxin abolished the actions of PGE2, 5-HT and DMPP, but did not influence the contractile response to Ach. Atropine blocked contractile response to PGE2 and Ach, blocked or inhibited the responses to 5-HT and DMPP. Hexamethonium blocked or inhibited effects of PGE2 and DMPP, and inhibited the effect of 5-HT. The contractile response of circular muscle to Ach was not affected. Nicotine blocked the effect of PGE2 also, but did not affect the response to Ach. Desensitization of the tissue to 5-HT and methysergide abolished or inhibited the contractile effect of 5-HT and PGE2, leaving intact the effect of Ach. Morphine abolished the effect of PGE2, but did not affect the response to Ach. The results imply that PGE2 is able to induce rhythmic, peristalsis-like contraction of the circular intestinal smooth muscle mainly by activation of cholinergic, and, at least partly, noncholinergic neurons, probably indoleaminergic.
Grbović
L
L
Radmanović
B Z
BZ
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D015232:Dinoprostone; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D011458:Prostaglandins E / Q000494:pharmacology*; D012701:Serotonin / Q000494:pharmacology
D011458:Prostaglandins E; D012701:Serotonin; D004246:Dimethylphenylpiperazinium Iodide; D015232:Dinoprostone; D000109:Acetylcholine