Involvement of Rho-Kinase in Lung Ischemia-Reperfusion Injury Pathogenesis: Molecular Analysis in an Isolated Rat Lung Perfusion Model

Rho-kinase, which is a key regulator of cytoskeletal dynamics, is an intracellular serine/threonine kinase. Recent studies have demonstrated that Rho-kinase is involved in ischemia-reperfusion injury (IRI) pathogenesis of many organs; however, its involvement with lung IRI remains unexamined. This study assessed the association of Rho-kinase with lung IRI and evaluated the protective effect of Rho-kinase inhibitors in lung IRI. The study included isolated rat lung perfusion models, divided into three groups: sham, RKI, and WI (n = 6, each). In the RKI and WI groups, the lungs were exposed to 60-min warm ischemia by perfusion cessation. At the onset of ischemia, nebulized fasudil, a novel Rho-kinase inhibitor, and saline were inhaled in the RKI and WI groups, respectively. Perfusion was restarted after the ischemic period and physiologic data were collected for 90 min. In the sham group, lungs were continuously perfused without ischemia or drug administrations. Protein expression in tissue specimens related to the Rho-kinase pathway was evaluated by Western blotting. Warm ischemia and subsequent reperfusion enhanced Rho-kinase activity in the WI group, and this was suppressed by fasudil treatment in the RKI group (Fig. A). Fasudil treatment significantly attenuated IRI pathophysiology, including pulmonary vascular contraction, dynamic compliance, lung edema, and oxygenation. Molecular analysis showed that Rho-kinase suppressed myosin phosphatase (Fig. A) and endothelial nitric oxide synthase (Fig. B) activities, suggesting these to be downstream targets of Rho-kinase during lung IRI pathogenesis. The present study suggests that Rho-kinase activation is involved in lung IRI pathogenesis, and Rho-kinase inhibitors may attenuate this pathogenesis.