Stimulation of Muscarinic Receptors Activate Acid Sensing Ion Channel 1 in Isolated Mesenteric Artery Endothelial Tubes

Abstract

Acid sensing ion channel 1 (ASIC1) belongs to the amiloride‐sensitive degenerin/epithelial sodium channel superfamily and is permeable to both Na+ and Ca2+. ASIC1 is expressed in vascular smooth muscle and/or endothelial cells of various vascular beds and is activated following stimulation of G protein‐coupled receptors (GPCR). In the pulmonary circulation, ASIC1 contributes to GPCR‐induced vasoconstriction and vascular smooth muscle Ca2+ influx via a store‐operated Ca2+ entry (SOCE) mechanism. In small mesenteric arteries, we have recently shown that ASIC1 contributes to acetylcholine (ACh)‐induced vasodilation and endothelial cell Ca2+ entry, however ASIC1‐mediated Ca2+ influx is not SOCE‐dependent in mesenteric artery endothelial cells. Thus, further investigation is needed to understand the mechanism by which ASIC1 is activated by GPCR in small mesenteric artery endothelial cells. Previous studies show ASIC1 is activated by arachidonic acid, therefore we hypothesized that acetylcholine stimulates ASIC1 in mesenteric artery endothelial cells through activation of phospholipase A2 (PLA2) and release of arachidonic acid. To test this hypothesis, we examined endothelial Ca2+ influx via Mn2+ quenching of fura‐2 fluorescence in freshly isolated mesenteric artery endothelial tubes. The PLA inhibitor methyl arachidonyl fluorophosphonate (MAF; 500 nM) attenuated the Ca2+ entry response to ACh, confirming that PLA2‐signaling contributes to the ACh‐induced Ca2+ entry in mesenteric artery endothelial cells. In addition, the selective inhibitor of ASIC1, psalmotoxin 1 (PcTX1; 20 nM), attenuated arachidonic acid‐induced Ca2+‐influx in mesenteric artery endothelial tubes. Although these studies suggest stimulation of muscarinic receptors activate ASIC1 through a PLA2‐arachidonic acid signaling mechanism in mesenteric endothelium, further studies are needed to identify the downstream effector of ASIC1.Support or Funding InformationSupported by National Heart, Lung, and Blood Institute Grants R01 HL‐111084 (to N.L. Jernigan), T32 HL007736 (to T.C. Resta), and American Heart Association Grant 18TPA34110281 (to N.L. Jernigan).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.