Exclusive interaction between α1D‐adrenergic receptor and pannexin 1 can mediate vasoconstriction

Abstract

We recently demonstrated that pannexin1 (Panx1) channels release ATP in vascular smooth muscle cells after phenylephrine (PE) stimulation (Billaud et al, Circ Res, 2011). However, the participation of Panx1 in other contractile pathways has not been investigated. Therefore, we stimulated thoracodorsal arteries with angiotensin II, endothelin‐1, serotonin, ATP, KCl, noradrenaline and PE. Only noradrenaline and PE responses were altered by pannexin inhibitors suggesting that these responses occurred through an association between the α1D‐adrenergic receptor (α1D‐AR) and Panx1. These results were verified using duolink imaging of the α1D‐AR/Panx1 interaction. We hypothesized that disruption of this complex would alter vasoconstriction and therefore designed peptides against the Panx1 intracellular loop (IL) and carboxyl tail (CT). Only the Panx1 IL peptide decreased constriction to PE. We further tested the effect of the peptides on the integrity of the Panx1/α1D‐AR complex using co‐immunoprecipitation and verified that the peptides had no effect on Panx1 hexamerization and trafficking. We demonstrated this in vitro by co‐transfection of Panx1 and α1D‐AR plasmids in HEK cells. Electrophysiology confirmed PE‐induced Panx1 activation which was altered by Panx1 IL peptide. Our results show that Panx1 has an exclusive interaction with α1D‐AR in the regulation of vascular tone.