Nitric oxide and vasoactive intestinal polypeptide mediate non-adrenergic, non-cholinergic inhibitory transmission to smooth muscle of the rat gastric fundus.
The nitric oxide (NO) synthesis inhibitor NG-monomethyl L-arginine (L-NMMA) reduced NANC-mediated relaxations of isolated strips of the rat gastric fundus elicited by low frequencies or short periods of field stimulation, but D-NMMA had no effect. The inhibitory effect of L-NMMA on NANC-mediated relaxations was partially reversed by L-arginine but was not affected by D-arginine. A VIP antibody abolished the relaxant response to VIP and reduced the responses to stimulation. Residual responses to stimulation in the presence of VIP antibody were further reduced by L-NMMA. The tone of the fundus strip was slightly increased by L-NMMA and slightly reduced by L-arginine. The relaxation produced by VIP was slightly reduced by L-NMMA and enhanced by L-arginine. Relaxations produced by peptide histidine isoleucine, sodium nitroprusside or isoprenaline were not affected by L-NMMA or L-arginine. The results suggest that NO as well as VIP is involved in NANC-mediated relaxations of the rat gastric fundus.
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 / Q000187:drug effects*; D004558:Electric Stimulation; D005748:Gastric Fundus / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation*; D009569:Nitric Oxide / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000187:drug effects*; D014660:Vasoactive Intestinal Peptide / Q000276:immunology / Q000494:pharmacology*; D019323:omega-N-Methylarginine
D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D014660:Vasoactive Intestinal Peptide; D001120:Arginine