Rho-kinase-mediated suppression of KDR current in cerebral arteries requires an intact actin cytoskeleton

Abstract

This study examined the role of the actin cytoskeleton in Rho-kinase-mediated suppression of the delayed-rectifier K+ (KDR) current in cerebral arteries. Myocytes from rat cerebral arteries were enzymatically isolated, and whole cell KDR currents were monitored using conventional patch-clamp electrophysiology. At +40 mV, the KDR current averaged 19.8 ± 1.6 pA/pF (mean ± SE) and was potently inhibited by UTP (3 × 10−5 M). This suppression was observed to depend on Rho signaling and was abolished by the Rho-kinase inhibitors H-1152 (3 × 10−7 M) and Y-27632 (3 × 10−5 M). Rho-kinase was also found to concomitantly facilitate actin polymerization in response to UTP. We therefore examined whether actin dynamics played a role in the ability of Rho-kinase to suppress KDR current and found that actin disruption using either cytochalasin D (1 × 10−5 M) or latrunculin A (1 × 10−8 M) prevented current modulation. Consistent with our electrophysiological observations, both Rho-kinase inhibition and actin disruption significantly attenuated UTP-induced depolarization and constriction of cerebral arteries. We propose that UTP initiates Rho-kinase-mediated remodeling of the actin cytoskeleton and consequently suppresses the KDR current, thereby facilitating the depolarization and constriction of cerebral arteries.