Action of 5-hydroxytryptamine on intestinal ion transport in the rat.
1. 5-HT increased the electrical activity of rat jejunum both in vivo and in vitro. The increased potential difference and short-circuit current resulted from a stimulation of electrogenic chloride secretion. NaCl absorption may also have been inhibited. 2. 5-HT did not alter cyclic AMP levels in isolated enterocytes. 3. The 5-HT response in vivo was unaffected by atropine, cyproheptadine, propranolol and hexamethonium. Phenoxybenzamine reduced the maximum response without affecting the dose required to produce a 50% maximum response. Methysergide, at a dose of 40 mg/kg, had a similar effect while a lower dose of 2 mg/kg produced no change. Mianserin competitively antagonized the response to 5-HT, a dose of 2 mg/kg producing a fourfold increase in the amount of 5-HT required to produce a 50% maximum response. 4. Acetylcholine and 5-HT seem to act independently in inducing intestinal secretion since atropine did not block the response to 5-HT and Mianserin did not alter the response to acetylcholine. 5. Experiments in which the intestinal villi or crypts were subjected to preferential damage suggested that 5-HT primarily produced its response at the crypt cell level.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007583:Jejunum / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051381:Rats; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism
D002712:Chlorides; D012702:Serotonin Antagonists; D012701:Serotonin; D012964:Sodium; D000242:Cyclic AMP