title: Amelioration of salt-induced vascular dysfunction in mesenteric arteries of Dahl salt-sensitive rats by missense mutation of extracellular superoxide dismutase.
abstract: Superoxide dismutase (SOD) enzymes, including extracellular SOD (ecSOD), are important for scavenging superoxide radicals (O2(·-)) in the vasculature. This study investigated vascular control in rats [SS-Sod(3m1Mcwi) (ecSOD(E124D))] with a missense mutation that alters a single amino acid (E124D) of ecSOD that produces a malfunctioning protein in the salt-sensitive (Dahl SS) genetic background. We hypothesized that this mutation would exacerbate endothelial dysfunction due to elevated vascular O2(·-) levels in SS, even under normal salt (NS; 0.4% NaCl) conditions. Aortas of ecSOD(E124D) rats fed standard rodent chow showed enhanced sensitivity to phenylephrine and reduced relaxation to acetylcholine (ACh) vs. SS rats. Endothelium-dependent dilation to ACh was unaffected by the mutation in small mesenteric arteries of ecSOD(E124D) rats fed NS diet, and mesenteric arteries of ecSOD(E124D) rats were protected from endothelial dysfunction during short-term (3-5 days) high-salt (HS; 4% NaCl) diet. ACh-induced dilation of mesenteric arteries of ecSOD(E124D) rats and SS rats fed NS diet was inhibited by N(G)-nitro-l-arginine methyl ester and/or by H2O2 scavenging with polyethylene glycol-catalase at higher concentrations of ACh. Total SOD activity was significantly higher in ecSOD(E124D) rats vs. SS controls fed HS diet, most likely reflecting a compensatory response to loss of a functional ecSOD isoform. These findings indicate that, contrary to its effect in the aorta, this missense mutation of ecSOD in the SS rat genome has no negative effect on vascular function in small resistance arteries, but instead protects against salt-induced endothelial dysfunction, most likely via compensatory mechanisms involving an increase in total SOD activity.
authors: Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
authors: Andreas M
authors: AM
authors: Beyer
authors: Gabor
authors: G
authors: Raffai
authors: Brian D
authors: BD
authors: Weinberg
authors: Katherine
authors: K
authors: Fredrich
authors: Matthew S
authors: MS
authors: Rodgers
authors: Aron M
authors: AM
authors: Geurts
authors: Howard J
authors: HJ
authors: Jacob
authors: Melinda R
authors: MR
authors: Dwinell
authors: Julian H
authors: JH
authors: Lombard
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000503:physiopathology; D002374:Catalase / Q000494:pharmacology; D008638:Mesenteric Arteries / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D020125:Mutation, Missense; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000494:pharmacology; D020303:Rats, Inbred Dahl; D017673:Sodium Chloride, Dietary / Q000378:metabolism / Q000633:toxicity*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D014664:Vasodilation
chemical_list: D017673:Sodium Chloride, Dietary; C070295:catalase-polyethylene glycol; D010656:Phenylephrine; D011092:Polyethylene Glycols; D002374:Catalase; C499089:Sod3 protein, rat; D013482:Superoxide Dismutase; D000109:Acetylcholine; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester
keywords: endothelial function; endothelium; oxidant stress; reactive oxygen species; salt-sensitive hypertension; superoxide anion