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ACTION OF HISTAMINE RECEPTOR AGONISTS AND ANTAGONISTS ON THE RAT UTERUS
Author(s) -
BERTACCINI G.,
MOLINA E.,
VITALI T.,
ZAPPIA L.
Publication year - 1979
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1979.tb16091.x
Subject(s) - dimaprit , histamine , histamine h2 receptor , agonist , chemistry , histamine receptor , receptor , medicine , histamine h3 receptor , endocrinology , pharmacology , biology , biochemistry , antagonist
1 Histamine and a series of compounds acting selectively on H r and H 2 ‐receptors were tested on the isolated oestrous uterus of the rat. 2 Histamine had a dose‐dependent inhibitory effect on the contractions elicited by acetylcholine. This action was unaffected by H 1 ‐blockers but was competitively inhibited by H 2 ‐blockers. The H 1 ‐selective agonist, 2‐(2‐aminoethyl)thiazole was ineffective at doses 100 times greater than those of histamine. Conversely, all the H 2 ‐agonists showed activity in the order of potency: N' ‐methylhistamine > histamine > N'‐N' ‐dimethylhistamine > 5‐methylhistamine > 5‐methyl‐ N' ‐methylhistamine. Among the non‐imidazole compounds, dimaprit had an activity identical to that of histamine, but all the dimaprit‐like compounds showed negligible activity. 3 The data obtained suggest that in the rat uterus, (a) the activation of H 2 ‐receptors is responsible for the inhibitory effect of histamine and its analogues; (b) the integrity of the histamine molecule seems to be less crucial than that of the dimaprit molecule for the maintenance of the H 2 ‐activity, since changes in its structure modify but do not abolish the biological activity as they do in the case of dimaprit; (c) the order of activity of the various H 2 ‐receptor agonists is different from that observed in other tissues.