Simvastatin reduces reperfusion injury by modulating nitric oxide synthaseexpression: an ex vivo study in isolated working rat hearts

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. Meth ods: Isolated working rat hearts were subjected to 15 min global ischemia a nd 22-180 min reperfusion in the presence or absence of simvastatin (10-100 muM). We evaluated creatinephosphokinase and nitrite levels in coronary ef fluent, heart weight changes, microvascular permeability (extravasation of fluoresceine-labeled albumin), ultrastructural alterations, and the express ion of endothelial (e) and inducible (i) nitric oxide synthase (NOS) (by re verse-transcribed polymerase chain reaction and Western blotting) in the pr esence or absence of the transcriptional inhibitor actinomycin-D. Results: Simvastatin (25 muM) significantly reduced myocardial damage and vascular h yperpermeability, concomitant with a reduction in endothelial and cardiomyo cyte lesions. Protection became less evident at 50 muM and reverted to incr eased damage at 100 muM. At 25 muM, simvastatin significantly increased eNO S mRNA and protein compared with untreated hearts, probably due to a post-t ranscriptional regulation since unaltered by animal pretreatment with actin omycin D. Simvastatin also significantly decreased iNOS mRNA and protein, a s well as nitrite production after ischemia-reperfusion. The addition of th e NOS inhibitor N-w-nitro-L-arginine methylester (L-NAME, 30 muM) to 25 muM simvastatin-treated hearts significantly reduced cardioprotection against ischemia-reperfusion. Conclusions: In this model, in the absence of perfusi ng granulocytes, the acute administration of a pharmacologically relevant s imvastatin concentration reduces ischemia-reperfusion injury and prevents c oronary endothelial cell and cardiomyocyte damage by cholesterol-independen t, NO-dependent mechanisms. (C) 2001 Elsevier Science BY. All rights reserv ed.