Supplementary Figure 13: Proposed mechanism for K+ regulation of CBF.
From: Capillary K+-sensing initiates retrograde hyperpolarization to increase local cerebral blood flow
Neural activity (1) leads to an increase in local K+ around capillaries (2). Through activation of KIR channels (3), this generates local hyperpolarization of the capillary endothelial membrane, which then spreads to adjacent ECs, presumably through gap junctions, activating KIR channels to rapidly propagate a regenerative electrical signal upstream to the feed arteriole (4). After spreading into adjacent SM cells (SMC), hyperpolarization deactivates voltage-dependent Ca2+ channels (VDCC). The ensuing decrease in intracellular Ca2+ causes SM relaxation and arteriolar dilation (5), promoting an increase in blood flow into the capillaries (6).
