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Effect of neuropeptide Y on adrenergic and non‐adrenergic, non‐cholinergic responses in the rat anococcygeus muscle
Author(s) -
Vila E.,
Tabernero A.,
Fernandes F.,
Salaices 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.tb14464.x
Subject(s) - endocrinology , medicine , neuropeptide y receptor , stimulation , prazosin , adrenergic , sodium nitroprusside , chemistry , cholinergic , tyramine , biology , neuropeptide , nitric oxide , receptor , antagonist
1 The effects of neuropeptide Y (NPY) were examined on adrenergic and non‐adrenergic, non‐cholinergic (NANC) neurotransmission in the rat anococcygeus muscle. 2 NPY (0.1–0.3 μ m ) greatly potentiated the contractile responses induced by field stimulation. Prazosin (0.1 μ m ) completely abolished the stimulation‐induced responses either in the absence or presence of NPY. 3 NPY (0.1–0.3 μ m ) enhanced only the contractile responses to low doses of noradrenaline (NA, 0.003–0.01 μ m ). Responses to tyramine were unaffected by the same concentrations of NPY. 4 In superfused anococcygeus, previously loaded with [ 3 H]‐NA, NPY (0.1–0.3 μ m ) failed to modify the basal, as well as the stimulation‐evoked, release of tritium at 2 and 4 Hz. 5 NANC relaxations induced by electrical stimulation were significantly reduced, in a concentration‐related manner, by 0.1–0.3 μ m NPY. 6 l ‐N G ‐nitro‐arginine ( l ‐NOARG, 30 μ m ) enhanced the stimulation (0.25–1 Hz)‐induced motor responses. In the presence of l ‐NOARG (30 μ m ), NPY (0.1 μ m ) did not modify the motor responses induced by field stimulation (0.25–0.5 Hz). l ‐Arginine did not reverse the NPY‐induced potentiation of stimulation‐induced motor responses. 7 The relaxations of anococcygeus muscle induced by sodium nitroprusside (SNP, 0.01–0.3 μ m ) were diminished by NPY (0.1–0.3 μ m ). 8 Our study suggests that NPY, at concentrations devoid of contractile effect, potentiates the motor responses of rat anococcygeus muscle as a consequence, at least in part, of the inhibition of NANC relaxing responses by a different mechanism from l ‐NOARG.