title: Regulation of arteriolar tone and responses via L-arginine pathway in skeletal muscle.
abstract: With in vivo television microscopy, changes in arteriolar diameter to topical administration of various vasoactive agents were examined in the absence or in the presence of NG-monomethyl-L-arginine (L-NMMA, topical 100 microM) or NG-nitro-L-arginine (L-NNA, 2.5 microM, 20 microliters/min ia), specific inhibitors of endothelium-derived relaxing factor (EDRF) biosynthesis. In cremaster muscle arterioles (15-22 microns) of rats (n = 6-11), dilations to acetylcholine (1-100 ng) were significantly inhibited (60-70%) by either of the arginine analogues. This inhibition was reversed by subsequent administration of 1 mM L-arginine. Dose-dependent constriction to norepinephrine was enhanced by L-NMMA. Indomethacin treatment reduced arteriolar dilation to bradykinin (BK, 1-100 ng), which was significantly inhibited by additional administration of L-NNA. Application of L-NNA first, followed by additional indomethacin, elicited similar results. Dilations to sodium nitroprusside and adenosine were not reduced in the presence of the inhibitors. L-NMMA or L-NNA caused no change in systemic blood pressure but elicited a significant reduction in arteriolar diameter; this effect was not reversed by 1 mM L-arginine. These data demonstrate the presence of an L-arginine pathway to produce EDRF (nitric oxide) in skeletal muscle microcirculation that mediates and/or modulates arteriolar responses to vasoactive agents and could contribute to the regulation of basal vascular tone.
authors.affiliation: Department of Physiology, New York Medical College, Valhalla 10595.
authors.forename: G
authors.initials: G
authors.lastname: Kaley
authors.forename: A
authors.initials: A
authors.lastname: Koller
authors.forename: J M
authors.initials: JM
authors.lastname: Rodenburg
authors.forename: E J
authors.initials: EJ
authors.lastname: Messina
authors.forename: M S
authors.initials: MS
authors.lastname: Wolin
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D001160:Arterioles / Q000187:drug effects / Q000502:physiology*; D001920:Bradykinin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009132:Muscles / Q000098:blood supply*; D019335:Nitroarginine; D051381:Rats; D011919:Rats, Inbred Strains; D014666:Vasomotor System / Q000502:physiology*; D019323:omega-N-Methylarginine
chemical_list: D019335:Nitroarginine; D019323:omega-N-Methylarginine; D001120:Arginine; D001920:Bradykinin; D007213:Indomethacin