Role of nitrergic nerves in the regulation of motility of the omasum and abomasum in healthy sheep (Ovis aries).
We examined the physiological role of nitrergic nerves in the regulation of omasal and abomasal motility in conscious healthy sheep and omasal muscle specimens. Nitric oxide (NO)-donor, S-nitroso-acethyl-dl-penicillamine (SNAP, 3-30 nmol/kg per min, i.v.) significantly inhibited omasal electromyographic (EMG) activity, whereas it did not alter EMG activity in the abomasal antrum. However, NO synthase inhibitor, Nomega-nitro-l-arginine-methyl ester (L-NAME, 0.3-3.0 micromol/kg per min, i.v.) did not alter EMG activity of the omasum and abomasum. In the in vitro experiments, SNAP application (6-200 micromol/l) significantly inhibited bethanechol (10 micromol/l)-induced contraction of longitudinal and circular muscles of the omasum. L-NAME application (0.03-3.0 mmol/l) enhanced electric field stimulation-induced contractions of the circular muscles. The results suggest that the omasal muscles are responsive to exogenous NO and that nitrergic nerves innervate the circular muscle layer of the omasum, however, nitrergic nerves are not or scarcely involved the physiological regulation of omasal and possibly abomasal motility in healthy sheep.
Onaga
Takenori
T
Laboratory of Veterinary Physiology, Department of Biosciences, School of Veterinary Medicine, Rakuno Gakuen University, 582 Bunkyodai-Midorimachi, Ebetsu, Hokkaido 069-8501, Japan. onaga@rakuno.ac.jp
Hara
Noriko
N
Shimizu
Yasuhito
Y
D000018:Abomasum / Q000294:innervation* / Q000502:physiology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005769:Gastrointestinal Motility / Q000187:drug effects*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D026602:Nitrergic Neurons / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009851:Omasum / Q000294:innervation* / Q000502:physiology; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D012756:Sheep / Q000033:anatomy & histology / Q000502:physiology*
D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester