Pannexin‐1 regulates eNOS activation through a superoxide‐dependent pathway (LB652)

Abstract

Pannexin‐1 (Panx1) is expressed in smooth muscle and endothelial cells of resistance arteries. In smooth muscle, Panx1‐formed channels mediate the α1‐adrenergic receptor‐initiated constriction, but the function of Panx1 in endothelial cells has not been determined. We analyzed the participation of Panx1 in the NO‐mediated dilation induced by the endothelium‐dependent vasodilator acetylcholine (ACh) in rat mesenteric resistance arteries contracted with 70 mM KCl. The activating phosphorylation of eNOS at serine 1177 (P‐eNOSS1177) and Akt at serine 473 (P‐AktS473) was evaluated by Western blot and superoxide production was detected using dihydroethidine. Blockade of Panx1 channels with probenecid, but not connexin‐formed hemichannel inhibition with La+3, enhanced the ACh‐induced vasodilation. Consistent with this, treatment with Panx1 channel blockers, probenecid or the mimetic peptide 10Panx, elicited an increase in P‐eNOSS1177, which was associated with a rise in P‐AktS473 and superoxide production. This effect of Panx1 blockers was not altered by ACh stimulation and was abolished by TEMPOL, a superoxide dismutase mimetic. It has been shown that superoxide production can lead to Akt activation by P‐AktS473. Therefore, these results indicate that Panx1 controls eNOS activity. Panx1 channel blockade initiates a superoxide‐dependent pathway that elicits Akt‐mediated eNOS activation via P‐eNOSS1177.FONDECYT 1100850