title: Effects of nitric oxide donor and nitric oxide synthase inhibitor on ruminal contractions in conscious sheep.
abstract: The present study was planned to evaluate a role of nitric oxide (NO) in the regulation of regular ruminal contractions in conscious sheep. Intravenous infusion of S-nitroso-acetyl-DL-penicillamine (SNAP) at doses of 3-30 nmol kg(-1) min(-1)for 30 minutes inhibited both the amplitude and frequency of ruminal contractions in a dose-dependent manner. However, intravenous infusion of Nomega-nitro-L-arginine-methyl ester (L-NAME) at doses of 0.3-3.0 micromol kg(-1) min(-1)did not alter the basal tone of intraruminal pressure and the amplitude of ruminal contractions. The frequency of contractions was slightly inhibited by L-NAME infusion at 1.0 micromol kg(-1)min(-1). The effects of L-NAME were abolished by simultaneous infusion of L -arginine at 30 micromol kg(-1) min(-1). These results suggest that exogenous NO can diminish the ruminal contractions, while endogenous NO is not involved in the regulatory mechanism of basal tone and regular phasic contractions of the rumen in healthy sheep.
authors.affiliation: Veterinary Physiology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan. onaga@rakuno.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Onaga
authors.forename: H
authors.initials: H
authors.lastname: Okada
authors.forename: S
authors.initials: S
authors.lastname: Hagiwara
authors.forename: C
authors.initials: C
authors.lastname: Nagashima
authors.forename: H
authors.initials: H
authors.lastname: Inoue
authors.forename: W
authors.initials: W
authors.lastname: Korczynski
authors.forename: S
authors.initials: S
authors.lastname: Kato
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011312:Pressure; D012417:Rumen / Q000187:drug effects* / Q000502:physiology; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D012756:Sheep / Q000502:physiology*
chemical_list: D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D026423:S-Nitroso-N-Acetylpenicillamine; D001120:Arginine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester