title: Participation of M1 receptors in NO pathway in cat ileum.
abstract: Electrical field stimulation (EFS) elicited two types of responses from longitudinal muscle strips of the distal cat ileum: contraction at switching on the stimulation (in 62% of the strips) and inhibition of the phasic contractions at switching on the stimulation followed by contraction in 38% of the strips. In all strips the muscarinic acetylcholine subtype M1-receptor agonist (4-Hydroxy-2-butynyl)-1-trimethylammonium-m-chlorocarbanilate chloride (McN-A-343) increased the tone and amplitude of the spontaneous contractions. On this background EFS elicited an inhibition of the phasic contractions at switching on the stimulation followed by contraction. Blockade of nitric oxide (NO)-synthase by Nw-nitro-L-arginine (L-NNA) transformed the inhibitory response into contraction and this transformation was partly overcome by L-arginine. The results suggest that presynaptically situated M1 receptors are involved in the NO pathway.
authors.affiliation: Institute of Physiology, Bulgarian Academy ofSciences, Sofia. CORT@IPH.BIO.BAS.BG
authors.forename: N
authors.initials: N
authors.lastname: Kortezova
authors.forename: L
authors.initials: L
authors.lastname: Shikova
authors.forename: M
authors.initials: M
authors.lastname: Papasova
mesh_terms: D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride / Q000494:pharmacology*; D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D007082:Ileum / Q000187:drug effects; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D019335:Nitroarginine / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000187:drug effects* / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D018721:Muscarinic Agonists; D011976:Receptors, Muscarinic; D019335:Nitroarginine; D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride; D019001:Nitric Oxide Synthase