Pharmacologic induction of vascular extracellular superoxide dismutase expression in vivo

Tatsiana Suvorava1, Marc Oppermann1, Vera Balz2, Georg Kojda1
1Institute of Pharmacology, University Hospital, Duesseldorf, Germany, 2Otorinolaringology Clinic, University Hospital, Duesseldorf, Germany

Pentaerythritol tetranitrate (PETN) treatment reduces progression of atherosclerosis and of endothelial dysfunction and decreases oxidation of LDL in rabbits. These effects have been linked to decreased vascular superoxide production but the underlying molecular mechanism remains unknown. We investigated the effect of (PETN) and of overexpression of endothelial nitric oxide synthase (eNOS++) on expression and activity of extracellular superoxide dismutase (ecSOD). Methods: C57BL/6 mice were randomized to receive placebo or increasing doses of PETN for four weeks and eNOS++-mice with a several fold higher endothelial-specific eNOS-expression were generated. Expression of ecSOD was determined in lung and aortic tissue by real time-PCR and Western blot. ecSOD activity was measured using inhibition of cytochrome-C reduction. Results: There was no effect of PETN treatment or eNOS overexpression on ecSOD mRNA, while ecSOD protein expression increased from 2.5-fold to 3.6-fold (p<0.05) by 6 mg PETN/kg BW/day and 60 mg PETN/kg BW/day, respectively. A similar increase was found in aortic homogenates. eNOS++ lung cytosols showed an increase of ecSOD protein level of 142±10.5% as compared to transgene negative littermates (P<0.05), which was abolished by nitro-L-arginine treatment. In each animal group the increase of ecSOD expression was paralled by an increase of ecSOD activity. Conclusions: Increased expression and activity of microvascular ecSOD are induced by an increased bioavailability of vascular NO. Upregulation of ecSOD likely represents a mechanism underlying antioxidative and antiatherosclerotic effects of PETN.