Evidence that part of the NANC relaxant response of guinea-pig trachea to electrical field stimulation is mediated by nitric oxide.
1. The nitric oxide (NO) synthesis inhibitors NG-monomethyl L-arginine (L-NMMA) and L-nitroarginine methyl ester (L-NAME) reduced relaxations of guinea-pig tracheal smooth muscle elicited by stimulation of intramural non-adrenergic, non-cholinergic (NANC) nerves, but D-NMMA had no effect. L-NAME was 10-30 times more potent than L-NMMA. Relaxations produced by sodium nitroprusside and vasoactive intestinal polypeptide (VIP) were not affected by L-NMMA or L-NAME. 2. The inhibitory effect of L-NMMA on NANC-mediated relaxations was partially reversed by L-arginine but was not affected by D-arginine. 3. VIP antibody and alpha-chymotrypsin abolished or greatly reduced the relaxant action of VIP and reduced relaxations elicited by stimulation of NANC nerves; the residual NANC relaxation was further reduced by L-NAME. 4. The results suggest that NO and VIP are mediators of NANC-induced relaxations of guinea-pig tracheal smooth muscle. We propose the term 'nitrergic' to describe transmission processes which are mediated by NO.
Li
C G
CG
Department of Pharmacology, University of Melbourne, Victoria, Australia.
Rand
M J
MJ
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000502:physiology*; D002918:Chymotrypsin / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000494:pharmacology*; D019335:Nitroarginine; D009599:Nitroprusside / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000276:immunology / Q000494:pharmacology; D019323:omega-N-Methylarginine
D009599:Nitroprusside; D019335:Nitroarginine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D014660:Vasoactive Intestinal Peptide; D001120:Arginine; D002918:Chymotrypsin