A functional coupling of TRPA1 and TMEM16A channels regulates endothelium-dependent hyperpolarization-mediated vasorelaxation of mesenteric resistance arteries in healthy and septic mice

Vascular endothelial dysfunction drives sepsis progression and multi-organ failure. Although TRPA1 and TMEM16A are expressed in the vasculature, their roles in arteriolar vasorelaxation remain unclear. The vasorelaxant effects of TRPA1 and TMEM16A on the second-order branch of mesenteric resistance arteries were investigated in healthy and septic mice using a Mulvany-style wire myograph. Fluorescent Ca 2+ assays were employed to assess cytosolic Ca 2+ ([Ca 2+ ] i ) in vascular endothelial cells (VECs). A mouse sepsis model was constructed through the method of cecal ligation and puncture (CLP). Both TRPA1 and TMEM16A activation induced endothelium-dependent hyperpolarization (EDH)-mediated relaxation via functional coupling: TRPA1 triggered Ca 2+ influx and Ca 2+ -induced Ca 2+ release, amplifying TMEM16A activity. In sepsis, while ACh/EDH responses were impaired, TRPA1/TMEM16A-mediated relaxation remained intact. Channel activation improved septic mouse survival and restored ACh responses, with plasma and assay agonist concentrations in comparable ranges. This study not only elucidates the protective role of endothelial TRPA1 and TMEM16A channels against sepsis-induced vascular inflammation but also provides potential new targets for sepsis therapy.