Defining the Molecular Basis of KIR Channel Mechanosensitivity in Vascular Smooth Muscle

Abstract

In cerebral arteries, the inwardly rectifying potassium channel (KIR) contributes to the setting of membrane potential and development of myogenic tone. KIR channels have been recently identified as a target of mechanical regulation in vascular smooth muscle, by which their activity is suppressed by pressure. However, the mechanism underlying this process remains unknown. The actin cytoskeleton and caveolae are often part of signaling domains implicated in established models of mechanosensitivity. Consequently, this study investigated whether these distinct structural components enable KIR pressure sensing in rat cerebral arterial smooth muscle. Whole‐cell patch clamp electrophysiology was used to monitor KIR activity and initial experiments confirmed that this current was suppressed by mechanical stimulation. Pre‐treatment of cells with actin‐disrupting agents, Latrunculin A and Cytochalasin D, prevented the suppression of KIR, indicative of the cytoskeleton’s participation. As KIR channels reside in caveolae, we next assessed the involvement of caveolin proteins in mechanoregulation. As expected, inhibition of caveolin‐1 signaling with blocking peptides diminished the ability of KIR channels to respond to pressure. The current data highlights that the actin cytoskeleton and caveolae form key parts of a signal transduction structure that confers mechanosensitivity to KIR. Ongoing work seeks to identify other KIR‐protein interactions in cerebral arterial smooth muscle using pull‐down and proximity ligation assay techniques. The functional impact of signaling complex disruption will also be assessed with vessel myography.Support or Funding InformationResearch supported by the Canadian Institutes of Health Research.