Grant: Discovery Grants Program - Individual

Blood flow to essential organs is set by a range of vasoactive stimuli, one of the most important being intravascular pressure. The "myogenic response" refers to the ability of arteries to sense elevated pressure and to induce constriction by depolarizing vascular smooth muscle and inducing a rise in cytosolic calcium (Ca2+), via L-type Ca2+ channels. My lab has a Long-Term interest in this hemodynamic response and defining the ion channels enabling pressure-dependent depolarization. Recent work completed by trainees (undergraduate/graduate student/postdoctoral fellows) and supported by my 2017-2023 NSERC Discovery Grant, revealed that pressure, in addition to activating depolarizing currents, inhibits inwardly rectifying K+ (KIR) channels, a hyperpolarizing conductance. How pressure regulates smooth muscle KIR remains unclear although data guides us in two directions, the first being to a mechano-complex and the second towards ion channel trafficking. My Short-Term goal is to define the mechanism by which pressure regulates smooth muscle KIR channels in the cerebral circulation. Two aims are forwarded: 1) Identify a role for mechano-complex proteins in pressure regulation of KIR; 2) Define a role for protein trafficking in pressure regulation of KIR. We first hypothesize that KIR is part of a caveolae mechano-complex comprised of caveolin-1, actin fibers, and alpha1-syntrophin, whose targeting impairs pressure regulation of this channel. We secondarily hypothesize that pressure inhibition of KIR depends in part on the net internalization of KIR2.2 from the plasma membrane. Our approach, from isolated smooth muscle cells to cerebral arteries, entails: 1) patch-clamp electrophysiology to monitor channel activity; 2) immunolabeling to define protein localization; and 3) pressure myography to assess function. Our focus on the KIR channel will impact our Long-Term Goal of understanding of the myogenic tone and how it optimizes blood vessel function by setting blood pressure, blood flow distribution and capillary filtration.