Preserved PAR2 calcium signalling in endothelial cells of hypertensive mice

Abstract

In hypertension where other signal transduction pathways are attenuated, protease‐activated receptor 2 (PAR2)‐mediated vascular relaxation is preserved. Despite this difference, PAR2 calcium events in vascular endothelium are not understood. We hypothesize that PAR2‐mediated calcium events are preserved in isolated mesenteric endothelial cells from hypertensive mice. Calcium activity was measured by spinning‐disk confocal microscopy in PAR2 wild type (PAR2‐WT) and PAR2 deficient (PAR2‐KO) mice treated subcutaneously with saline or angiotensin II (hypertensive). Isolated endothelial cells were incubated with fluorescent calcium indicator, fluo‐4 AM, and then exposed to a PAR2‐activating peptide 2‐furoyl LIGRLO‐amide (2fly) or muscarinic M3 agonist acetylcholine. Our results show the number of calcium release sites and event rate are preserved in hypertensive PAR2‐WT exposed to 2fly. Acetylcholine‐induced calcium release sites and event rate were attenuated by 21% and 24% respectively. Similar results were found in hypertensive PAR2‐KO. Two types of calcium event were identified; small peripheral and repetitive, large central amplitude events. We conclude that PAR2‐mediated calcium signaling in isolated resistance endothelial cells is preserved in hypertension. Research funded by Canadian Institutes of Health Research and Research & Development Corporation Newfoundland and Labrador.