KIR channels tune electrical communication in cerebral arteries

The conducted vasomotor response reflects electrical communication in the arterial wall and the distance signals spread is regulated by three factors including resident ion channels. This study defined the role of inward-rectifying K+ channels (KIR) in governing electrical communication along hamster cerebral arteries. Focal KCl application induced a vasoconstriction that conducted robustly, indicative of electrical communication among cells. Inhibiting dominant K+ conductances had no attenuating effect, the exception being Ba2+ blockade of KIR. Electrophysiology and Q-PCR analysis of smooth muscle cells revealed a Ba2+-sensitive KIR current comprised of KIR2.1/2.2 subunits. This current was surprisingly small and when incorporated into a model, failed to account for the observed changes in conduction. We theorized a second population of KIR channels exist and consistent with this idea, a robust Ba2+-sensitive KIR2.1/2.2 current was observed in endothelial cells. When both KIR currents were incorporated i...