title: Evidence for a differential release of nitric oxide and vasoactive intestinal polypeptide by nonadrenergic noncholinergic nerves in the rat gastric fundus.
abstract: The roles of vasoactive intestinal polypeptide (VIP) and nitric oxide (NO) in nonadrenergic noncholinergic (NANC) nerve-mediated relaxations were investigated in longitudinal muscle strips of the rat gastric fundus. Transmural stimulation (1-16 Hz for 2 min), VIP and noradrenaline evoked a prolonged relaxation of the rat gastric fundus, whereas NO evoked a transient relaxation. Only the electrically induced responses were blocked by tetrodotoxin. The inhibitor of NO biosynthesis NG-nitro-L-arginine (L-NNA) preferentially inhibited the relaxations induced by low frequency stimulation. In contrast, trypsin mainly reduced the electrically induced relaxations to high frequency stimulation; the NANC relaxations resistant to trypsin were further inhibited by L-NNA. VIP-induced relaxations were abolished by trypsin, but remained unaffected by L-NNA. NO- or noradrenaline-induced relaxations were not inhibited by either L-NNA or trypsin alone, whereas the combination of L-NNA and trypsin slightly reduced the noradrenaline-induced responses. These results suggest that NANC responses in the rat gastric fundus at low frequency are mediated mainly by NO, whereas at higher frequency NO together with a peptide, probably VIP, are released.
authors.affiliation: Division of Gastroenterology, Faculty of Medicine, University of Antwerp, Wilrijk, Belgium.
authors.forename: G E
authors.initials: GE
authors.lastname: Boeckxstaens
authors.forename: P A
authors.initials: PA
authors.lastname: Pelckmans
authors.forename: J G
authors.initials: JG
authors.lastname: De Man
authors.forename: H
authors.initials: H
authors.lastname: Bult
authors.forename: A G
authors.initials: AG
authors.lastname: Herman
authors.forename: Y M
authors.initials: YM
authors.lastname: Van Maercke
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004357:Drug Synergism; D004558:Electric Stimulation; D004566:Electrodes; D005260:Female; D005748:Gastric Fundus / Q000187:drug effects / Q000294:innervation* / Q000378:metabolism*; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism*
chemical_list: D019335:Nitroarginine; D009569:Nitric Oxide; D012701:Serotonin; D014660:Vasoactive Intestinal Peptide; D013779:Tetrodotoxin; D001120:Arginine; D014357:Trypsin