title: Effect of NG-monomethyl-L-arginine on endothelium-dependent relaxation of human subcutaneous resistance arteries.
abstract: 1. Using a myograph to measure isometric tension, we have looked at the action of NG-monomethyl-L-arginine on the endothelium-dependent relaxation of human subcutaneous resistance arteries. 2. NG-Monomethyl-L-arginine, the novel inhibitor of endothelium-derived relaxing factor synthesis, caused concentration-dependent but only partial inhibition of maximal relaxation induced by acetylcholine in human subcutaneous resistance arteries. 3. The inhibitory action of NG-monomethyl-L-arginine on acetylcholine-induced maximal relaxation was partially reversed by incubation of the arteries in equimolar concentrations of L-arginine and NG-monomethyl-L-arginine. Subsequent incubation in L-arginine led to further reversal, but this was no greater than with incubation in physiological saline. 4. A component of acetylcholine-induced relaxation was sensitive to indomethacin, suggesting that this response is mediated by prostanoids as well as by endothelium-derived relaxing factor. 5. NG-Monomethyl-L-arginine did not increase the tension of resting human subcutaneous resistance arteries. NG-Monomethyl-L-arginine did enhance the contractile response to noradrenaline, possibly due to inhibition of release of endothelium-derived relaxing factor resulting from stimulation of alpha 2-adrenoreceptors on the endothelial cells.
authors.affiliation: Department of Physiology, St Thomas' Hospital, London.
authors.forename: R G
authors.initials: RG
authors.lastname: Woolfson
authors.forename: L
authors.initials: L
authors.lastname: Poston
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001158:Arteries / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004727:Endothelium / Q000502:physiology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000037:antagonists & inhibitors*; D009638:Norepinephrine / Q000494:pharmacology; D019323:omega-N-Methylarginine
chemical_list: D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D000109:Acetylcholine; D009638:Norepinephrine; D007213:Indomethacin