Inhibition of Rho-kinase protects the heart against ischemia/reperfusion injury

OBJECTIVE: To investigate the role of Rho A and Rho-kinase in acute myocardial ischemia/reperfusion injury and the protective effect of Rho-kinase inhibitor, Y-27632 [(R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)cyclohexanecarboxamide]. METHODS AND RESULTS: Male CD1 mice were subjected to 30 min of coronary occlusion and 24 h reperfusion. Ischemia/reperfusion upregulated expression of Rho A in ischemic myocardium, and subsequently activated Rho-kinase. Y-27632 significantly inhibited the activation of Rho-kinase following ischemia/reperfusion. Treatment with Y-27632 at 10 and 30 mg/kg oral administration, reduced infarct size by 30.2% and 41.1%, respectively (P<0.01 vs. vehicle). Y-27632 also enhanced post-ischemia cardiac function. Left ventricular systolic pressure, +dP/dt and -dP/dt were significantly improved by 23.5%, 52.3%, and 59.4%, respectively (P<0.01 vs. vehicle). Moreover, Y-27632 reduced ischemia/reperfusion-induced myocardial apoptosis. The apoptotic myocytes in ischemic myocardium after 4 h reperfusion were reduced from 13.1% in vehicle group to 6.4% in Y-27632-treated group (P<0.01). Meanwhile, ischemia/reperfusion-induced downregulation of Bcl-2 in myocardium was remarkably attenuated in the treated animals. Ischemia/reperfusion resulted in remarkable elevation in serum levels of proinflammatory cytokines, interleukin-6 (IL-6), keratinocyte chemoattractant (KC) and granulocyte colony-stimulating factor (G-CSF), which was significantly suppressed by Y-27632. In addition, Y-27632 decreased ischemia/reperfusion-induced accumulation of neutrophils in the heart by 45% (P<0.01). CONCLUSIONS: These results suggest that Rho-kinase plays a pivotal role in myocardial ischemia/reperfusion injury. The cardiac protection provided by treatment with a selective Rho-kinase inhibitor is likely via anti-apoptotic effect and attenuation of ischemia/reperfusion-induced inflammatory responses. The finding of this study suggest a novel therapeutic approach to the treatment of acute myocardial ischemia/reperfusion injury.