Simvastatin improves endothelial function in spontaneously hypertensive rats through a superoxide dismutase mediated antioxidant effect.
BACKGROUND
Hydroxymethylglutaryl coenzyme A (HMGCoA) reductase inhibitors have beneficial effects beyond their cholesterol-lowering properties. The antioxidant mechanism of HMGCoA reductase inhibitors is not completely understood.


OBJECTIVE
To elucidate the antioxidant effect of simvastatin.


METHODS
We studied the influence of simvastatin treatment on the development of hypertension, modification of antioxidant systems, and reactivity of aortic rings in Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats.


RESULTS
Simvastatin had no effect on blood pressure (BP). Simvastatin treatment (either 1 or 2 mg/kg body weight for 12 or 20 weeks) increased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in SHR rats compared with untreated control SHR rats. Carbachol-induced relaxation of aortic rings was impaired in control SHR rats and was restored by simvastatin treatment. Addition of SOD improved the response in control SHR rats and did not have any effect in treated SHR rats. Addition of diethyldithiocarbamic acid, a selective inhibitor of SOD, produced a mild non-significant impairment in carbachol-induced relaxation in control SHR rats, suggesting a deficient antioxidant system in these animals. However, in treated SHR and in WKY rats, impairment of the relaxation was marked, implying that SOD activity in these animals was important to maintain endothelial function. In aortic rings without endothelium from SHR rats, contraction induced by free radicals was substantially higher than in WKY rats. This effect was attenuated in 1-mg-treated rats and abolished in 2-mg-treated rats.


CONCLUSIONS
Simvastatin promotes intracellular antioxidant systems, fundamentally SOD, restoring endothelial function but not having any effect on blood pressure.
Carneado
Joaquin
J
Hypertension and Lipids Unit, Department of Internal Medicine, Virgen del Rocío University Hospital, Seville, Spain. jcarneado@hvr.sas.cica.es
Alvarez de Sotomayor
Maria
M
Perez-Guerrero
Concepción
C
Jimenez
Luis
L
Herrera
Maria D
MD
Pamies
Encarnación
E
Martin-Sanz
Maria D V
MD
Stiefel
Pablo
P
Miranda
Maria
M
Bravo
Luis
L
Marhuenda
Elisa
E
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001011:Aorta / Q000187:drug effects / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology*; D005979:Glutathione Peroxidase / Q000378:metabolism; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR / Q000502:physiology*; D011921:Rats, Inbred WKY; D019821:Simvastatin / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism
D000975:Antioxidants; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D013481:Superoxides; D019821:Simvastatin; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase