5-HT3 receptors do not mediate vagally-induced relaxation or contraction of the isolated stomach of the guinea-pig.
1. We have tested whether 5-HT3 receptors mediate vagally-induced relaxation or contraction of the isolated stomach of the guinea-pig. 2. The antagonists of 5-HT3 receptors, ondansetron (1-10 microM) or metoclopramide (1-30 microM) did not inhibit vagally-induced relaxations at low concentrations but partially inhibited them at 30 microM or 60 microM, respectively. These higher concentrations of ondansetron and metoclopramide also inhibited relaxations induced by 1,1-dimethyl-4-phenylpiperazinium iodide (30 microM) but did not affect those induced by glyceryl trinitrate (0.7-1.1 microM). 3. Desensitization to 5-HT (100 microM) or 2-Me-5-HT (100 microM) did not affect relaxations or contractions induced by vagal stimulation. 4. Ondansetron (30 microM) or metoclopramide (60 microM) did not inhibit vagally-induced gastric contraction. 5. Thus, 5-HT3 receptors do not mediate vagally-induced relaxation or contraction in the guinea-pig stomach.
William Harvey Research Institute, St. Bartholomew's Hospital Medical College, Charterhouse Square, London.
K M
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Desai
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Warner
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Vane
D000818:Animals; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D008787:Metoclopramide / Q000494:pharmacology*; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D005996:Nitroglycerin / Q000494:pharmacology; D017294:Ondansetron / Q000494:pharmacology*; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D013270:Stomach / Q000187:drug effects / Q000502:physiology*; D014630:Vagus Nerve / Q000502:physiology*
D011985:Receptors, Serotonin; D012701:Serotonin; D017294:Ondansetron; D004246:Dimethylphenylpiperazinium Iodide; C045918:2-methyl-5-HT; D005996:Nitroglycerin; D008787:Metoclopramide