Beneficial effect of hydroxyfasudil, a specific Rho-kinase inhibitor, on ischemia/reperfusion injury in canine coronary microcirculation in vivo Original Research Article

Objectives We examined whether hydroxyfasudil, a specific Rho-kinase inhibitor, exerts cardioprotective effect on coronary ischemia/reperfusion (I/R) injury and, if so, whether nitric oxide (NO) is involved. Background Recent studies have demonstrated that Rho-kinase is substantially involved in the pathogenesis of cardiovascular diseases; however, it remains to be examined whether it is also involved in ischemia/reperfusion (I/R) injury. Methods Canine subepicardial small arteries (SA, ≥100 μm) and arterioles (A, <100 μm) were observed by a charge-coupled device intravital microscope during I/R. Coronary vascular responses to endothelium-dependent (acetylcholine, intracoronary [IC]) and -independent (papaverine, IC) vasodilators were examined after I/R under the following four conditions: control (n = 7), NO synthase inhibitor alone (NG-monomethl-L-arginine [L-NMMA], IC, n = 4), hydroxyfasudil alone (IC, n = 7), and hydroxyfasudil plus L-NMMA (n = 7). Results Hydroxyfasudil significantly attenuated serotonin (IC)-induced vasoconstriction of SA (−7 ± 1% vs. 2 ± 1%, p < 0.01). Coronary I/R significantly impaired coronary vasodilation to acetylcholine after I/R (SA, p < 0.05; and A, p < 0.01 vs. before I/R) and L-NMMA further reduced the vasodilation, whereas hydroxyfasudil completely preserved the responses. The vasoconstriction by L-NMMA after I/R was significantly improved by hydroxyfasudil in both-sized arteries (both p < 0.01). Expression of endothelial nitric oxide synthase (eNOS) protein in the ischemic endocardium of left anterior descending coronary artery area (as determined by Western blotting) significantly decreased (79 ± 4%) compared with the nonischemic endocardium of LCX area (100 ± 7%), which was improved by hydroxyfasudil (105 ± 6%, p < 0.01). Hydroxyfasudil significantly reduced myocardial infarct size, and hydroxyfasudil with L-NMMA also reduced the infarct size compared with L-NMMA alone. Conclusions Hydroxyfasudil exerts cardioprotective effects on coronary I/R injury in vivo, in which NO-mediated mechanism may be involved through preservation of eNOS expression.