title: Role of endothelium-derived nitric oxide in the regulation of tonus in large-bore arterial resistance vessels, arterioles and veins in cat skeletal muscle.
abstract: The role of endothelium-derived nitric oxide in the regulation of vascular resistance (tonus) in cat skeletal muscle was studied with the use of NG-monomethyl-L-arginine (L-NMMA), a specific inhibitor of nitric oxide formation from L-arginine. The study was performed with a whole-organ technique which permits simultaneous, continuous and quantitative recordings of resistance reactions in the whole vascular bed (RT) and in its three consecutive sections: large-bore arterial resistance vessels (greater than 25 microns; Ra,prox), small arterioles (less than 25 microns; Ra,micro) and veins (Rv). NG-monomethyl-L-arginine (3-100 mg kg-1 tissue, i.a.) induced a dose-dependent increase in resistance that was preferentially, but not selectively, confined to the large-bore arterial resistance vessels. At a maximally effective dose (100 mg kg-1), the nitric oxide inhibitor caused a marked constriction, within 5 min, on average increasing RT by 99%, Ra,prox by 138%, Ra,micro by 18% and Rv by 23%. The constrictor response to NG-monomethyl-L-arginine was long-lasting but disappeared gradually over a period of about 1 h. However, it could be abruptly abolished by excess L-arginine (300 mg kg-1, i.a.). The vasodilator response (RT) to acetylcholine was significantly attenuated in the presence of NG-monomethyl-L-arginine compared with the control response. The results suggested that nitric oxide formation from L-arginine by the vascular endothelium plays a fundamental role in the regulation of vascular resistance (tone) in vivo, with its main site of action located in the large-bore arterial resistance vessels.
authors.affiliation: Department of Physiology and Biophysics, University of Lund, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Ekelund
authors.forename: S
authors.initials: S
authors.lastname: Mellander
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001158:Arteries / Q000502:physiology; D001160:Arterioles / Q000502:physiology; D002415:Cats; D004730:Endothelium, Vascular / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014680:Veins / Q000502:physiology; D019323:omega-N-Methylarginine
chemical_list: D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine