Inhibition of Rho-Associated Kinase Results in Suppression of Neointimal Formation of Balloon-Injured Arteries

Abstract

Background —Rho-associated kinase (ROCK), an effector of small GTPase Rho, regulates vascular tone via a calcium sensitization mechanism and plays a key role in the pathogenesis of hypertension. However, its role in vascular growth remains unclear. Methods and Results —Y-27632, a specific ROCK inhibitor, and the overexpression of dominant-negative ROCK suppressed the mitogen-induced DNA synthesis of cultured vascular smooth muscle cells (VSMCs), which indicates the essential role of ROCK in the control of VSMC proliferation in vitro. Y-27632 also suppressed the chemotaxis of VSMCs. Male Wistar rats were systemically given Y-27632 (35 to 70 mg · kg −1 · day −1 ) through an intraperitoneal infusion. The neointimal formation of balloon-injured carotid arteries was significantly suppressed in Y-27632–treated rats (intima/media ratio, 0.22±0.02) compared with vehicle-treated rats (intima/media ratio, 0.92±0.21) or hydralazine-treated rats with a similar blood pressure decrease (intima/media ratio, 1.03±0.15). The phosphorylation of myosin phosphatase and myosin light chain was elevated in injured arteries in a Y-27632–sensitive manner, indicating the augmentation of ROCK activity in neointimal formation. The downregulation of the cyclin-dependent kinase inhibitor p27 kip1 in injured vessels was reversed by Y-27632 treatment, reflecting the antiproliferative effect of ROCK inhibition in vivo. Conclusions —We conclude that ROCK plays a key role in the process of neointimal formation after balloon injury. Thus, the inhibition of ROCK may be a potential therapeutic strategy for treating vascular proliferative disorders and hypertension.