From cells to organism: impact of dyslipidemia on inwardly rectifying K ⁺ channels and cerebral vascular function

Evidence increasingly suggests that dyslipidemia diminishes dilatory function of resistance arteries by altering ion channel activity. Focusing on the cerebral vasculature, this study investigated whether inwardly rectifying K⁺ 2.1 (K_IR2.1) channels are targeted early in dyslipidemia. Experiments began at the cellular level (patch-clamp electrophysiology), then progressed to isolated arteries (pressure myography) and whole animals (arterial spin-labeling magnetic resonance imaging). Lipid analysis confirmed dyslipidemia in <i>Ldlr</i>^-/- (normal chow) and C57BL/6 mice fed a high-fat high-cholesterol (HFHC) diet for 8 weeks; no aortic plaques were observed. Patch-clamp electrophysiology revealed a marked reduction in endothelial but not smooth muscle K_IR activity in both dyslipidemic models; this K_IR activity was recoverable by plasma membrane cholesterol depletion. These cellular changes notably diminished flow-induced vasodilation in cerebral arteries isolated from both dyslipidemic models; such deficits were observed in endothelial <i>Kir2.1</i>^-/- arteries. A blood pressure challenge induced a perfusion phenotype in HFHC-C57BL/6 but not genetic deletion (<i>Ldlr</i>^-/-) mice, consistent with reduced K_IR activity and flow-mediated dilation. Our findings highlight that endothelial K_IR2.1 channels are targeted early in dyslipidemia, which was associated with attenuated flow-mediated dilation in our acute HFHC model. This change likely moderates the range of blood flow control and substrate delivery to active brain tissue.