Lipophilic statins augment inducible nitric oxide synthase expression in cytokine-stimulated cardiac myocytes

Nitric oxide production by inducible nitric oxide synthase (iNOS) may play an important role in the pathogenesis of cardiovascular dysfunction. We investigated the effects of statins on iNOS expression and subsequent nitric oxide synthesis in cardiac myocytes and the mechanism by which statins exert their effects. We measured the production of nitrite, a stable metabolite of nitric oxide, in cultured neonatal rat cardiac myocytes with the Griess reagent. iNOS mRNA and protein expression were assayed by reverse transcription polymerase chain reaction and Western blotting, respectively. The lipophilic statins fluvastatin and lovastatin significantly increased interleukin-1beta-induced nitrite production by cardiac myocytes, whereas hydrophilic pravastatin did not. Increased nitrite production by fluvastatin was accompanied by increased iNOS mRNA and protein accumulation. Exogenous mevalonate, but not squalene, significantly blocked the stimulatory effect of fluvastatin on nitrite production. Cotreatment with geranylgeranyl-pyrophosphate also reversed the effect of fluvastatin. Furthermore, both Rho inhibitor C3 exoenzyme and Rho kinase inhibitor Y-27632 significantly increased interleukin-1beta-induced nitrite accumulation in cardiac myocytes. These results demonstrated that lipophilic statins upregulate iNOS expression and subsequent nitric oxide formation in cardiac myocytes via inhibition of Rho.