Abstract 1138: Impaired Flow-induced Vasodilation In Arterioles By Cholesterol-induced Suppression Of Endothelial Kir2.1

Abstract

Dyslipidemia is a critical factor in endothelial dysfunction; however, the mechanisms are still not well understood. Our studies showed that cholesterol-induced suppression of endothelial flow-sensitive Kir2.1 channels contributes significantly to the impairment of flow-induced vasodilation (FIV) in hypercholesterolemic ApoE -/- mice. Notably, a CRISPR mouse generated to substitute Kir2.1 with its cholesterol-insensitive mutant via a single-point mutation results in a full rescue of FIV under hypercholesterolemia. To extend our observations to humans, 16 healthy subjects were recruited with LDL-cholesterol ranging from 51-153 mg/dl, and FIV was assessed in resistance arterioles isolated from gluteal adipose. Kir2.1-dependent FIV was assessed by transducing intact resistance arteries with the adenoviral construct expressing dominant-negative Kir2.1 (dn-Kir2.1) driven by an endothelial-specific ( Cdh5 ) promoter. Our results show that Kir2.1-dependent FIV of resistance arteries contributed ~50% of the vasodilatory response in participants with normal/low LDL levels (<100 mg/dL) and was sharply reduced in participants with LDL levels >100 mg/dL. A significant negative correlation was observed between FIV and LDL, which was accounted for by the loss of Kir2.1-dependent FIV component. Furthermore, impaired FIV in in arteries from participants with high-LDL was fully rescued by overexpressing WT-Kir2.1 in the endothelium. These data suggest that cholesterol-induced suppression of Kir2.1 is a major mechanism underlying endothelial dysfunction in hypercholesterolemia. Mechanistically, we showed previously that Kir2.1 is required for the flow-activation of Akt1/eNOS. Our new data show that Kir2.1 is also required for the upstream event of flow-induced activation of Piezo1, PECAM1, PI3K and that transducing the arteries with endothelial specific construct of Akt1 stably located at the membrane (myrAkt1) eliminates the dependence of FIV on Kir2.1. Based on our observation, we conclude that Kir2.1 is required for the translocation of Akt1 to the membrane, and the cholesterol suppression of Kir2.1 interferes Akt1-dependent flow-induced NO production.