Objective: We tested the hypothesis of beneficial effects of the 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA)-reductase inhibitor simvastatin in a model of ischemia-reperfusion, and investigated potential mechanisms.
Methods: Isolated working rat hearts were subjected to 15 min global ischemia and 22-180 min reperfusion in the presence or absence of simvastatin (10-100 microM). We evaluated creatinephosphokinase and nitrite levels in coronary effluent, heart weight changes, microvascular permeability (extravasation of fluoresceine-labeled albumin), ultrastructural alterations, and the expression of endothelial (e) and inducible (i) nitric oxide synthase (NOS) (by reverse-transcribed polymerase chain reaction and Western blotting) in the presence or absence of the transcriptional inhibitor actinomycin-D.
Results: Simvastatin (25 microM) significantly reduced myocardial damage and vascular hyperpermeability, concomitant with a reduction in endothelial and cardiomyocyte lesions. Protection became less evident at 50 microM and reverted to increased damage at 100 microM. At 25 microM, simvastatin significantly increased eNOS mRNA and protein compared with untreated hearts, probably due to a post-transcriptional regulation since unaltered by animal pretreatment with actinomycin D. Simvastatin also significantly decreased iNOS mRNA and protein, as well as nitrite production after ischemia-reperfusion. The addition of the NOS inhibitor N(pi)-nitro-L-arginine methylester (L-NAME, 30 microM) to 25 microM simvastatin-treated hearts significantly reduced cardioprotection against ischemia-reperfusion.
Conclusions: In this model, in the absence of perfusing granulocytes, the acute administration of a pharmacologically relevant simvastatin concentration reduces ischemia-reperfusion injury and prevents coronary endothelial cell and cardiomyocyte damage by cholesterol-independent, NO-dependent mechanisms.