Vascular Inward Rectifier K+ Channels as External K+ Sensors in the Control of Cerebral Blood Flow. (April 2015)

• Record Type: Journal Article
• Authors: Longden, Thomas A.; Nelson, Mark T.
• Is Part Of: Microcirculation. Volume 22:Number 3(2015:Apr.)
• Page Start: 183
• Page End: 196
• Publication Date: 2015-04
• Subjects: Biological transport -- Periodicals; Microcirculation -- Physiology -- Periodicals; 612.135
• DOI: 10.1111/micc.12190
• Languages: English
• ISSNs: 1073-9688

Abstract

<abstract abstract-type="main" id="micc12190-abs-0001"> <title>Abstract</title> <p>For decades it has been known that external K⁺ ions are rapid and potent vasodilators that increase CBF. Recent studies have implicated the local release of K⁺ from astrocytic endfeet—which encase the entirety of the parenchymal vasculature—in the dynamic regulation of local CBF during NVC. It has been proposed that the activation of K_IR channels in the vascular wall by external K⁺ is a central component of these hyperemic responses; however, a number of significant gaps in our knowledge remain. Here, we explore the concept that vascular K_IR channels are the major extracellular K⁺ sensors in the control of CBF. We propose that K⁺ is an ideal mediator of NVC, and discuss K_IR channels as effectors that produce rapid hyperpolarization and robust vasodilation of cerebral arterioles. We provide evidence that K_IR channels, of the K_IR2 subtype in particular, are present in both the endothelial and SM cells of parenchymal arterioles and propose that this dual positioning of K_IR2 channels increases the robustness of the vasodilation to external K⁺, enables the endothelium to be actively engaged in NVC, and permits electrical signaling through the endothelial syncytium to promote upstream vasodilation to modulate CBF.</p> </abstract>