Open AccessCOMPARATIVE STUDIES WITH 5-HYDROXYTRYPTAMINE AND ITS DERIVATIVES IN ISOLATED, BLOOD-PERFUSED SMALL INTESTINE AND TLEUM STRIP OF THE RAT
Author(s) -
Kazushige Sakai,
Michitaka Akima,
Yasuyuki Shiraki
Publication year - 1979
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.29.223
Subject(s) - methysergide , phentolamine , ileum , tetrodotoxin , atropine , hexamethonium , chemistry , jejunum , serotonin , medicine , small intestine , endocrinology , contraction (grammar) , pharmacology , biology , propranolol , biochemistry , receptor
The mode of actions of 5-hydroxytryptamine (5-HT) and its derivatives, tryptophan (TP), 5-hydroxytryptophan (5-HTP) and 5-hydroxyindole acetic acid (5-HIAA) was studied on the isolated, blood-perfused small intestine and isolated ileum strip of rats. In the isolated, blood-perfused intestinal preparations, 5-HT and 5-HTP injected into the superior mesenteric artery caused a monophasic fast contraction, while TP and 5-HIAA had no effects on the intestine. The contractile responses to 5-HT and 5-HTP were abolished by tetrodotoxin (TTX), hexamethonium (C6) and morphine, but were resistant to blockade of either atropine, methysergide or phentolamine. On the other hand, in the ileum strip preparations, 5-HT contracted the ileum, but its derivatives had no effects on the ileum. TTX, C6, morphine and atropine failed to prevent the contractile response to 5-HT, whereas methysergide effectively antagonized the response. The present results indicate that 5-HT acts by exciting intramural neuronal elements or by directly contracting the smooth muscle of the intestine. 5-HTP seems to act in the same manner as 5-HT.