title: Acetylcholine-induced relaxation of peripheral arteries isolated from mice lacking endothelial nitric oxide synthase.
abstract: 1. Acetycholine-mediated relaxations in phenylephrine-contracted aortas, femoral and mesenteric resistance arteries were studied in vessels from endothelial nitric oxide synthase knock-out (eNOS -/-) and the corresponding wild-type strain (eNOS +/+) C57BL6/SV19 mice. 2. Aortas from eNOS (+/+) mice relaxed to acetylcholine in an endothelium-dependent NG-nitro-L-arginine (L-NOARG) sensitive manner. Aortas from eNOS (-/-) mice did not relax to acetylcholine but demonstrated enhanced sensitivity to both authentic NO and sodium nitroprusside. 3. Relaxation to acetylcholine in femoral arteries was partially inhibited by L-NOARG in vessels from eNOS (+/+) mice, but relaxation in eNOS (-/-) mice was insensitive to a combination of L-NOARG and indomethacin and the guanylyl cyclase inhibitor 1H-[1,2, 4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). The L-NOARG/ODQ/indomethacin-insensitive relaxation to acetylcholine in femoral arteries was inhibited in the presence of elevated (30 mM) extracellular KCl. 4. In mesenteric resistance vessels from eNOS (+/+) mice, the acetylcholine-mediated relaxation response was completely inhibited by a combination of indomethacin and L-NOARG or by 30 mM KCl alone. In contrast, in mesenteric arteries from eNOS (-/-) mice, the acetylcholine-relaxation response was insensitive to a combination of L-NOARG and indomethacin, but was inhibited in the presence of 30 mM KCl. 5. These data indicate arteries from eNOS (-/-) mice demonstrate a supersensitivity to exogenous NO, and that acetylcholine-induced vasorelaxation of femoral and mesenteric vessels from eNOS (-/-) mice is mediated by an endothelium-derived factor that has properties of an EDHF but is neither NO nor prostacyclin. Furthermore, in mesenteric vessels, there is an upregulation of the role of EDHF in the absence of NO.
authors.affiliation: Smooth Muscle Research Group and Department of Pharmacology and Therapeutics, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada, T2N 4N1.
authors.forename: G J
authors.initials: GJ
authors.lastname: Waldron
authors.forename: H
authors.initials: H
authors.lastname: Ding
authors.forename: F
authors.initials: F
authors.lastname: Lovren
authors.forename: P
authors.initials: P
authors.lastname: Kubes
authors.forename: C R
authors.initials: CR
authors.lastname: Triggle
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001158:Arteries / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D001685:Biological Factors / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009126:Muscle Relaxation / Q000187:drug effects; D009569:Nitric Oxide / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D019335:Nitroarginine / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology
chemical_list: D001685:Biological Factors; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; C067410:endothelium-dependent hyperpolarization factor; D009599:Nitroprusside; D019335:Nitroarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D000109:Acetylcholine