Purinergic signalling in mesenteric vascular smooth muscle in a mice model of essential hypertension

Abstract

In vascular smooth muscle cells (VSMCs) non‐selective cation channels such as TRPC3 and TRPC6 have been proposed as the molecular constituents of receptor‐(ROCs) and stretch‐(SOCs) operated channels linking DAG signaling cascade pathway with increased vascular tone. The membrane depolarization caused by TRPCs can increase Ca2+ entry leading to augmented [Ca2+]I and VSMC contraction. Therefore, by influencing membrane potential, TRPC channels could play an important role controlling the increased vascular tone present in several pathologies, such as essential hypertension. We have previously described an increased functional expression of TRPC3 channels in mesenteric VSMCs from hypertensive mice that can contribute to increased vascular tone by favouring depolarization (Alvarez‐Miguel et al., J Physiol, in press). As several mechanosensitive G‐protein coupled receptors (GPCR) are linked to the DAG‐dependent activation of TRPC3/6 channels, we explore here the contribution of this signalling pathway to the increased vascular tone in hypertension.Using a mouse model of essential hypertension (BPH mice) and its normotensive control (BPN mice) we explored changes in the molecular components of the mechanotransduction pathway in hypertension. We analized the expression of mechanosensitive ion channels and some VSMCs sensor elements, including GPCRs, channels and transporters with qPCR. Their functional contribution was studied in isolated VSMCs (using electrophysiology) and in intact mesenteric arteries with pressure myography.Real‐time PCR showed an increased expression of some of the elements of the purinergic signalling pathway, including purinergic receptors P2Y2 and P2Y6, TRPC3 channels and the Ca2+‐activated Cl− channel Clca1. Pressure myography of mesenteric arteries after endothelium removal showed a vasoconstriction response to ATP, UTP and UDP. ATP‐induced vasoconstriction was not different between BPN and BPH arteries. The EC50 of the effect was around 7–10 μM in both preparations, and it could be blocked by α‐β‐methilene‐ATP. UTP‐induced vasoconstriction was not affected by α‐β‐methilene‐ATP and was significantly larger in BPH arteries: 50 μM UTP‐elicited vasoconstriction represented 40% of the maximal response to ATP in BPN arteries and 150% in BPH arteries. Our data indicate that mesenteric vascular reactivity to ATP is not altered in our hypertension model, but there is an increased contribution of the purinergic GPCR signalling pathway to the increased vascular tone. Together with the observed upregulation of P2YR receptors in BPH VSMCs, the augmented functional expression of TRPC3 channels could participate in the increased vasoconstriction observed in response to uridine nucleotides in BPH mesenteric arterieSupport or Funding InformationSupported by grants ISCIII‐FEDER RD12/0042/0006, (Heracles Program), BFU2013‐45867‐R (MINECO) and by a Junta de Castilla y Leon fellowship to IAM