Effect of fluvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on nitric oxide-induced hydroxyl radical generation in the rat heart

Abstract

We examined the effect of fluvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on the production of hydroxyl radical ( ⋅OH) generation via nitric oxide synthase (NOS) activation by an in vivo microdialysis technique. The microdialysis probe was implanted in the left ventricular myocardium of anesthetized rats and tissue was perfused with Ringer’s solution through the microdialysis probe at a rate of 1 μl/min. Sodium salicylate in Ringer’s solution (0.5 nmol/μl/min) was infused directly through a microdialysis probe to detect the generation of ⋅OH. Induction of [K +] o (70 mM) or tyramine (1 mM), significantly increased the formation of ⋅OH trapped as 2,3-dihydroxybenzoic acid (DHBA). The application of N G-nitro- l-arginine methyl ester ( l-NAME), a NOS inhibitor, significantly decreased the K + depolarization-induced ⋅OH formation, but the effect of tyramine significantly increased the level of 2,3-DHBA. When fluvastatin (100 μM), an inhibitor of low-density lipoprotein (LDL) oxidation, was administered to l-NAME-pretreated animals, both KCl and tyramine failed to increase the level of 2,3-DHBA formation. The effect of fluvastatin may be unrelated to K + depolarization-induced ⋅OH generation. To examine the effect of fluvastatin on ischemic/reperfused rat myocardium, the heart was subjected to myocardial ischemia for 15 min by occlusion of the left anterior descending coronary artery (LAD). When the heart was reperfused, a marked elevation of the level of 2,3-DHBA was observed. However, in the presence of fluvastatin (100 μM), the elevation of 2,3-DHBA was not observed in ischemia/reperfused rat heart. Fluvastatin, orally at a dose of 3 mg/kg/day for 4 weeks, significantly blunted the rise of serum creatine phosphokinase and improved the electrocardiogram 2 h after coronary occlusion. These results suggest that fluvastatin is associated with a cardioprotective effect due to the suppression of noradrenaline-induced ⋅OH generation by inhibiting LDL oxidation in the heart.