title: Nitric oxide mediates the neural nonadrenergic, noncholinergic relaxation of pig tracheal smooth muscle.
abstract: In pig tracheal smooth muscle, the isometric tension responses to electrical field stimulation (EFS) were studied after raising the tone with carbamylcholine chloride (carbachol). EFS induced frequency-dependent relaxations that were nonadrenergic, noncholinergic (NANC) in nature. Addition of NG-nitro-L-arginine (L-NOArg), an inhibitor of nitric oxide (NO) synthesis from L-arginine, resulted in concentration-dependent inhibition of the relaxation response to EFS. Pretreatment of the tissues with L-arginine (1 mM) prevented the inhibitory effect of L-NOArg on the EFS-induced relaxations at the frequencies studied. However, in the presence of D-arginine, EFS-induced relaxations were inhibited by L-NOArg. L-Arginine, D-arginine, and L-NOArg had no significant effects on basal tone of the muscle. In the presence of L-NOArg, vasoactive intestinal polypeptide (3 x 10(-7) M), the nicotinic agonist dimethylphenyl piperazinium bromide (100 microM), and isoproterenol (1 microM) relaxed carbachol-induced tone. The concentration-dependent selective inhibition of neural relaxation by L-NOArg and its reversal by L-arginine in a stereospecific manner are consistent with NO-mediated NANC relaxation of pig tracheal smooth muscle.
authors.affiliation: Department of Veterinary PathoBiology, College of Veterinary Medicine, University of Minnesota, St. Paul 55108.
authors.forename: M S
authors.initials: MS
authors.lastname: Kannan
authors.forename: D E
authors.initials: DE
authors.lastname: Johnson
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D004558:Electric Stimulation; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000294:innervation / Q000502:physiology*; D009424:Nervous System Physiological Phenomena; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine; D009994:Osmolar Concentration; D013552:Swine; D014132:Trachea / Q000294:innervation / Q000502:physiology*
chemical_list: D019335:Nitroarginine; D009569:Nitric Oxide; D002217:Carbachol; D001120:Arginine