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Contractile effects of substance P and neurokinin A on the rat stomach in vivo and in vitro
Author(s) -
HolzerPetsche Ulrike,
Lembeck Fred,
Seitz Helmut
Publication year - 1987
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.1476-5381.1987.tb16849.x
Subject(s) - neurokinin a , substance p , bethanechol , methysergide , in vivo , endocrinology , medicine , neurokinin b , chemistry , atropine , tetrodotoxin , muscarinic acetylcholine receptor , cholinergic , muscle contraction , pharmacology , neuropeptide , biology , antagonist , receptor , microbiology and biotechnology
1 Substance P and neurokinin A (substance K) were infused into the coeliac artery of anaesthetized rats at doses of 0.06–20 nmol min − . Both tachykinins caused contractions of the stomach, the threshold dose of neurokinin A being 10 times lower than of substance P. The dose‐response curve for substance P was flatter than that for neurokinin A. 2 On circular muscle strips from the rat gastric corpus in vitro , the dose‐response curves for both tachykinins were parallel, neurokinin A being 10 times more potent than substance P. The contractions in response to 10 μ m neurokinin A and to 30 μ m substance P were 58 and 54%, respectively, of the maximal contraction to bethanechol (1 m m ). 3 The effect of substance P was reduced by atropine both in vivo and in vitro. In vitro , the contractions to substance P were also reduced by tetrodotoxin but left unaffected by methysergide. The action of neurokinin A was not affected by these drugs. 4 It is concluded that neurokinin A contracts rat stomach by a direct action on the circular smooth muscle, whereas the action of substance P is mediated, at least in part, by cholinergic interneurones.