Long-term treatment with eicosapentaenoic acid ameliorates myocardial ischemia-reperfusion injury in pigs in vivo: Involvement of rho-kinase pathway inhibition

Background: Eicosapentaenoic acid (EPA), the major n-3 fatty acid in fish oil, exerts cardioprotective effects against ischemic heart disease; however, the detailed mechanisms remain to be elucidated. Rho-kinase plays an important role in the pathogenesis of cardiovascular diseases including ischemia-reperfusion (I/R) injury. Thus, the hypothesis that long-term EPA treatment ameliorates myocardial I/R injury through Rho-kinase pathway inhibition in pigs in vivo was investigated. Methods and Results: Male pigs were treated with either a control chow or EPA (600 · mg · kg ^-1 · day ^-1) for 3 weeks (n=8 each) and were subjected to myocardial ischemia by 90-min occlusion of the left circumflex coronary artery and subsequent 60-min reperfusion. The EPA group had an increased EPA level in red blood cells (4.4±0.3 mol%). The EPA treatment significantly ameliorated myocardial I/R injury, including regional wall motion abnormality (EPA 5.3±3.6 vs. control 35.1±3.8 unit, P<0.0001), left ventricular ejection fraction (EPA 43±9% vs. control 32±7%, P<0.05), occurrence of ventricular arrhythmias (EPA 181±73 vs. control 389±51 events, P<0.0001) and histological accumulation of inflammatory cells (P<0.01). Importantly, the EPA treatment significantly inhibited myocardial Rho-kinase activity (assessed by the extent of the myosin-binding subunit phosphorylation) (EPA 0.47±0.11 vs. control 0.77±0.14, P<0.05) and preserved myocardial eNOS activity (EPA 0.56±0.13 vs. control 0.23±0.07, P<0.01) with a significant correlation noted between them. Conclusions: Long-term treatment with EPA ameliorates I/R injury partly through Rho-kinase pathway inhibition in vivo.