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

Luykenaar KD, El-Rahman RA, Walsh MP, Welsh DG. Rhokinase-mediated suppression of K-DR current in cerebral arteries requires an intact actin cytoskeleton. Am J Physiol Heart Circ Physiol 296: H917-H926, 2009. First published February 13, 2009; doi:10.1152/ajpheart.01206.2008.-This study examined the role of the actin cytoskeleton in Rho-kinase-mediated suppression of the delayed-rectifier K+ (K-DR) 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 x 10(-5) M). This suppression was observed to depend on Rho signaling and was abolished by the Rho-kinase inhibitors H-1152 (3 x 10(-7) M) and Y-27632 (3 x 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 x 10(-5) M) or latrunculin A (1 x 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.