Y-27632, a Rho-Associated Protein Kinase Inhibitor, Inhibits Voltage-Dependent K+ Channels in Rabbit Coronary Arterial Smooth Muscle Cells

We examined the effects of the Rho-associated protein kinase (ROCK) inhibitor Y-27632 on voltage-dependent K+ (Kv) channels in rabbit coronary arterial smooth muscle cells using the whole-cell patch clamp technique. Y-27632 reduced the amplitude of the Kv current in a concentration-dependent manner, with an IC50 of 0.87 ± 0.06 μmol/l and a Hill coefficient of 1.48 ± 0.06. Y-27632 did not affect the steady-state activation or inactivation curves, suggesting that the drug does not affect the voltage sensitivity of Kv channels. Another ROCK inhibitor, H-1152, did not affect the Kv current and had no significant effect on the Y-27632-induced inhibition of Kv channels, indicating that the inhibitory effect of Y-27632 on the Kv current is independent of ROCK signaling. From these results, we conclude that Y-27632 inhibits the Kv channel current in a dose-dependent and ROCK signaling-independent manner.