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Influence of N G ‐nitro‐L‐arginine on non‐adrenergic non‐cholinergic relaxation in the guinea‐pig gastric fundus
Author(s) -
Lefebvre R.A.,
Baert E.,
Barbier A.J.
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.tb14311.x
Subject(s) - guanethidine , vasoactive intestinal peptide , endocrinology , medicine , stimulation , guinea pig , tetrodotoxin , arginine , atropine , cholinergic , nitroarginine , chemistry , adrenergic , inhibitory postsynaptic potential , nitric oxide , nitric oxide synthase , neuropeptide , amino acid , biochemistry , receptor
1 The influence of N G ‐nitro‐ l ‐Arginine ( l ‐NNA) on non‐adrenergic non‐cholinergic (NANC) relaxations induced by electrical field stimulation was investigated in circular muscle strips of the guinea‐pig gastric fundus. 2 In the presence of 10 −6 m . atropine and 4 × 10 −6 m guanethidine, electrical field stimulation (40 V, 1 ms, 0.125–16 Hz) with 10 s trains at 5 min intervals induced short‐lasting, frequency‐dependent relaxations. Continuous stimulation, with cumulative increase of the stimulation frequency, induced sustained frequency‐dependent relaxations. Both types of response were abolished by 3 × 10 −6 m tetrodotoxin. 3 l ‐NNA (10 −5 m and 10 −4 m ) concentration‐dependently reduced both types of NANC response. Pre‐incubation with 2 × 10 −3 m l ‐arginine prevented the inhibitory action of 10 −5 m l ‐NNA and partially antagonized that of 10 −4 m l ‐NNA. d ‐arginine (2 × 10 −3 m ) did not protect against the inhibitory effect of l ‐NNA. 4 l ‐NNA did not consistently influence the basal tone of the tissues. l ‐Arginine and d ‐arginine likewise did not influence basal tone; they also had no influence on the electrically‐induced NANC relaxations. 5 NO (10 −6 −10 −4 m ) induced short‐lasting concentration‐dependent relaxations, while vasoactive intestinal polypeptide (VIP, (10 −9 −10 −7 m ) induced more sustained relaxations, that developed at a slower rate. The NO‐ and VIP‐induced relaxations were not influenced by 10 −4 m l ‐NNA. 6 These results suggest that NO is involved in NANC neurotransmission of the guinea‐pig gastric fundus; its contribution to sustained NANC relaxation in the guinea‐pig gastric fundus is much more important than in the rat.