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Modulation of non‐adrenergic non‐cholinergic inhibitory neurotransmission in rat gastric fundus by the α 2 ‐adrenoceptor agonist, UK‐14,304
Author(s) -
Lefebvre R.A.,
Smits G.J.M.
Publication year - 1992
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.1476-5381.1992.tb14495.x
Subject(s) - rauwolscine , prazosin , endocrinology , medicine , stimulation , inhibitory postsynaptic potential , agonist , yohimbine , adrenergic , vasoactive intestinal peptide , chemistry , neurotransmitter , neurotransmission , cholinergic , receptor , antagonist , neuropeptide
1 The influence of the α 2 ‐adrenoceptor agonist, UK‐14,304, on non‐adrenergic non‐cholinergic (NANC) relaxation induced by electrical field stimulation was investigated in longitudinal muscle strips of the gastric fundus of reserpinized rats. 2 In tissues where tone was raised by 3 × 10 −7 m prostaglandin F2α (PGF 2α ), the inhibitory effect of 10 −6 m UK‐14,304, on the NANC relaxations induced by short train stimulation (40 V, 1 ms, 20 s) was inversely related to the stimulus frequency (1‐4‐16 Hz). UK‐14,304 (10 −6 m ) did not influence relaxations induced by administration of exogenous nitric oxide (NO, 2 × 10 −6 m −10 −4 m ). The inhibitory effect of UK‐14,304 on the electrically induced relaxations was antagonized by 10 −6 m rauwolscine but not by 10 −6 m prazosin. 3 UK‐14,304 (10 −6 m ) also reduced the amplitude of the sustained NANC relaxation, induced by electrical field stimulation (40 V, 1 ms, 4 Hz) for 5 min. The effect of UK‐14,304 was also antagonized by 10 −6 m rauwolscine but not by 10 −6 m prazosin. UK‐14,304 (10 −6 m ) did not reduce the relaxation induced by 3 × 10 −9 m . vasoactive intestinal polypeptide (VIP). 4 These results suggest that the release of the inhibitory NANC neurotransmitter during short train stimulation, thought to be NO, and during sustained stimulation, thought to be VIP, is inhibited by stimulation of presynaptic α 2 ‐adrenoceptors in the rat gastric fundus.