Prejunctional inhibition of non-adrenergic non-cholinergic transmission in the rat anococcygeus muscle.
The muscarinic agonist McN-A-343 did not affect the tone or nitroprusside-induced relaxations of the rat anococcygeus, but inhibited non-adrenergic non-cholinergic (NANC) relaxations. Atropine, pirenzepine and gallamine blocked the McN-A-343 inhibition of NANC relaxations. Agonists of alpha 1-(methoxamine) or alpha 2-adrenoceptors (clonidine, rilmenidine) increased tone and reduced NANC relaxations. Carbachol also increased tone but produced a greater reduction of NANC relaxations. The findings suggest that activation of prejunctional muscarinic receptors on NANC terminals inhibits transmitter release, but there is no evidence for prejunctional alpha-adrenoceptors.
Li
C G
CG
Department of Pharmacology, University of Melbourne, Victoria, Australia.
Rand
M J
MJ
D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000294:innervation*; D009411:Nerve Endings / Q000187:drug effects; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D009435:Synaptic Transmission / Q000187:drug effects*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D009599:Nitroprusside; D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride