title: Acute simvastatin increases endothelial nitric oxide synthase phosphorylation via AMP-activated protein kinase and reduces contractility of isolated rat mesenteric resistance arteries.
abstract: Statins can have beneficial cholesterol-independent effects on vascular contractility, which may involve increases in the bioavailability of NO (nitric oxide) as a result of phosphorylation of eNOS (endothelial NO synthase). Although this has been attributed to phosphorylation of Akt (also known as protein kinase B), studies in cultured cells have shown that statins can phosphorylate AMPK (AMP-activated protein kinase); it is unknown whether this has functional effects in intact arteries. Thus we investigated the acute effects of simvastatin on resistance arterial contractile function, evaluating the involvement of NO, Akt and AMPK. Isolated rat mesenteric resistance arteries were mounted on a wire myograph. The effects of incubation (1 and 2 h) with simvastatin (0.1 or 1 μM) on contractile responses were examined in the presence and absence of L-NNA (N-nitro-L-arginine; 10 μM) or mevalonate (1 mM). Effects on eNOS, phospho-eNOS (Ser1177), and total and phospho-Akt and -AMPK protein expression were investigated using Western blotting. The effect of AMPK inhibition (compound C, 10 μM) on eNOS phosphorylation and contractile responses were also studied. Simvastatin (1 μM, 2 h) significantly reduced constriction to U46619 and phenylephrine and enhanced dilations to ACh (acetylcholine) in depolarized, but not in U46619-pre-constricted arteries. These effects were completely and partially prevented by L-NNA and mevalonate respectively. Simvastatin increased eNOS and AMPKα phosphorylation, but had no effect on Akt protein expression and phosphorylation after 2 h incubation. Compound C prevented the effects of simvastatin on eNOS phosphorylation and contractility. Thus simvastain can acutely modulate resistance arterial contractile function via mechanisms that involve the AMPK/phospho-eNOS (Ser1177)/NO-dependent pathway.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Luciana V
authors.initials: LV
authors.lastname: Rossoni
authors.forename: Mark
authors.initials: M
authors.lastname: Wareing
authors.forename: Camilla F
authors.initials: CF
authors.lastname: Wenceslau
authors.forename: Mahmood
authors.initials: M
authors.lastname: Al-Abri
authors.forename: Chris
authors.initials: C
authors.lastname: Cobb
authors.forename: Clare
authors.initials: C
authors.lastname: Austin
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D055372:AMP-Activated Protein Kinases / Q000502:physiology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D019821:Simvastatin / Q000494:pharmacology*; D046509:Tissue Culture Techniques; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D014662:Vasoconstrictor Agents; D009569:Nitric Oxide; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D019821:Simvastatin; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases