Rho kinase activation plays a major role as a mediator of irreversible injury in reperfused myocardium

Abstract

Hamid SA, Bower HS, Baxter GF. Rho kinase activation plays a major role as a mediator of irreversible injury in reperfused myocardium. Am J Physiol Heart Circ Physiol 292: H2598 -H2606, 2007. First published January 12, 2007; doi:10.1152/ajpheart.01393.2006.-Intracellular signal transduction events in reperfusion following ischemia influence myocardial infarct development. Here we investigate the role of Rho kinase (ROCK) activation as a specific injury signal during reperfusion via attenuation of the reperfusion injury salvage kinase (RISK) pathway phosphatidylinositol 3-kinase (PI3K)/Akt/endothelial nitric oxide (NO) synthase (eNOS). Rat isolated hearts underwent 35 min of left coronary artery occlusion and 120 min of reperfusion. Phosphorylation of the ROCK substrate protein complex ezrin-radixin-moesin, assessed by immunoblotting and immunofluorescence, was used as a marker of ROCK activation. Infarct size was determined by tetrazolium staining, and terminal dUTP nick-end labeling (TUNEL) positivity was used as an index of apoptosis. The ROCK inhibitors fasudil or Y-27632 given 10 min before ischemia until 10 min after reperfusion reduced infarct size (control, 34.1 Ϯ 3.8%; 5 M fasudil, 18.2 Ϯ 3.1%; 0.3 M Y-27632, 19.4 Ϯ 4.4%; 5 M Y-27632, 9.2 Ϯ 2.9%). When 5 M Y-27632 was targeted specifically during early reperfusion, robust infarct limitation was observed (14.2 Ϯ 2.6% vs. control 33.4 Ϯ 4.4%, P Ͻ 0.01). The protective action of Y-27632 given at reperfusion was attenuated by wortmannin (29.2 Ϯ 6.1%) and N -nitro-L-arginine methyl ester (30.4 Ϯ 5.7%), confirming a protective mechanism involving PI3K/Akt/NO. Ezrin-radixin-moesin phosphorylation in risk zone myocardium confirmed early and sustained ROCK activation during reperfusion and its inhibition by Y-27632. Inhibition of ROCK activation at reperfusion reduced the proportion of TUNEL-positive nuclei in the infarcted region. In conclusion, ROCK activation occurs specifically during early reperfusion. Inhibition of ROCK at reperfusion onset limits infarct size through an Akt/eNOS-dependent mechanism, suggesting that ROCK activation at reperfusion may be deleterious through suppression of the RISK pathway. apoptosis; myocardial infarction; nitric oxide DESPITE THE UNQUESTIONED NEED for reperfusion to prevent ischemic necrosis in acute myocardial infarction, there is accumulating experimental evidence that reperfusion is associated with the paradoxical activation of lethal signals that culminate in necrosis/apoptosis. Indeed, recent experimental evidence suggests that reperfusion may contribute to a far greater extent than was previously supposed (8, 9). Whereas this does not detract from the proven therapeutic value of reperfusion, it prompts a reassessment of reperfusion injury and its mechanisms. Rho kinase (ROCK) is a family of serine/threonine protein kinases, stimulated by G proteincoupled receptor activation of small plasma membranebound GTP-binding proteins, such as the Rho and Rac family. Relevant to the pathophysiology of myocardial infarction, pot...

Endotoxin-induced renal tolerance against ischemia and reperfusion injury is removed by iNOS, but not eNOS, gene-deletion

“…It has been recognized that low amounts of NO generated by constitutive NOS (eNOS and nNOS) are beneficial (18). There have also been some reports that eNOS overexpression reduces I/R and hypoxic injury in a variety of tissues and cells (19)(20)(21)(22). Therefore, we determined the role of eNOS in the involvement of the eNOS protein in LPS-induced kidney tolerance.…”

Administration of the Rho-Kinase Inhibitor Fasudil Before Ischemia or just After Reperfusion, but not 30 min After Reperfusion, Protects the Stunned Myocardium in Swine

“…In the present study, we showed that fasudil administered just after reperfusion but not 30 min after reperfusion protected the stunned myocardium. Hamid et al reported that Rho-kinase activity increased 10 min after reperfusion but not during ischemia, and that Y27632 administered during early reperfusion significantly reduced the infarct size [8]. Thus fasudil administration during early reperfusion may protect against myocardial stunning as well as myocardial infarction.…”

“…Preischemic administration of the Rho-kinase inhibitors fasudil and Y-27632 decreased the incidence of arrhythmias and myocardial infarct size in rats subjected to transient LAD occlusion [5,6]. Recently, administration of the Rho-kinase inhibitor Y-27632 at early reperfusion was reported to have a cardioprotective effect against myocardial infarction [7,8]. Shibata et al 6 paragraph 3 deleted.…”

ROCK Inhibition – A New Therapeutic Avenue in Kidney Protection

“…In regard to this, it has recently been shown that ROCK) and their associated signaling pathways play pivotal roles in the development of (experimental) IRI. ROCK-inhibitors such as fasudil or Y-27632 have been shown to provide beneficial effects concerning different ischemic events such as renal (Kentrup D. et al 10 A.D.; Kentrup D. et al 2010;Prakash et al 2008;Teraishi et al 2004;Versteilen et al 2006;Versteilen et al 2011) myocardial (Bao et al 2004Hamid, Bower & Baxter, 2007;Wolfrum et al 2004), cerebral (Satoh et al 2008;Toshima et al 2000), hepatic (Du & Hannon, 2004;Ikeda et al 2003;Takeda et al 2003), and gastrointestinal (Santen et al 2010) ischemia. However, the exact mechanisms involved remain to be fully elucidated.…”