Vascular smooth muscle cells from small human omental arteries express P2X1 and P2X4 receptor subunits

Abstract

Stimulation of P2X receptors by ATP in vascular smooth muscle cells (VSMCs) is proposed to mediate vascular tone. However, understanding of P2X receptor-mediated actions in human blood vessels is limited, and therefore, the current work investigates the role of P2X receptors in freshly isolated small human gastro-omental arteries (HGOAs). Expression of P2X1 and P2X4 receptor subunit messenger RNA (mRNA) and protein was identified in individual HGOA VSMCs using RT-PCR and immunofluorescent analysis and using Western blot in multi-cellular preparations. ATP of 10 μmol/l and αβ-meATP of 10 μmol/l, a selective P2X receptor agonist, evoked robust increases in [Ca 2+ ] i in fluo-3-loaded HGOA VSMCs. Pre-incubation with 1 μmol/l NF279, a selective P2X receptor antagonist, reduced the amplitude of αβ-meATP-induced increase in [Ca 2+ ] i by about 70 %. ATP of 10 μmol/l and αβ-meATP of 10 μmol/l produced similar contractile responses in segments of HGOA, and these contractions were greatly reduced by 2 μmol/l NF449, a selective P2X receptor inhibitor. These data suggest that VSMCs from HGOA express P2X1 and P2X4 receptor subunits with homomeric P2X1 receptors likely serving as the predominant target for extracellular ATP.

Physiopathological implications of P2X1and P2X7receptors in regulation of glomerular hemodynamics in angiotensin II-induced hypertension

“…Immunofluorescence staining showed the localization of P2X 1 R, P2X 4 R, and P2X 7 R on the smooth muscle cells of intrarenal vessels in ANG II hypertensive rats; P2X 1 R localization is consistent with previous reports (10,30,40), whereas P2X 4 R distribution is predominantly endothelial (28). However, expression of P2X 7 R and P2X 4 R in the smooth muscle cells of small-and large-size vessels in both sham-operated and ANG II rats is a novel finding; previous studies have demonstrated a predominant endothelial localization, and scarce P2X 7 R in the smooth muscle of renal vessels and afferent arterioles (27,28).…”

“…In this context, expression of P2X 1 R in the smooth muscle cells of kidney vessels in sham-operated and hypertensive rats, as previously described (10,30,40), may contribute to the vasodilatory responses to receptor blockade as observed in the hypertensive group in this study. In addition, the effects on glomerular hemodynamics in sham-operated rats suggest a role for this receptor in regulating glomerular hemodynamics during normal physiological conditions.…”

Purinergic Signaling in the Cardiovascular System

“…The contractile actions of ATP released from perivascular sympathetic nerves are mediated principally via P2X1 receptors, confirmed by the use of P2X1 genetic knockout mice. However, in some vessels (eg, human omental arteries 71 and rat basilar arteries 72 ), smooth muscle cells also express P2X4 receptors. P2X5 and P2X1 receptors are expressed by rat small mesenteric arteries, 73 and P2X1/4 heteromeric receptors mediate constriction of rat cerebral arteries.…”

Purinoceptor: a novel target for hypertension

“…Stimulation of P2X1R mediated vasoconstriction in vascular smooth muscle cells (VSMCs) from human gastro-omental arteries [87]. In addition, P2X1R is activated by neurally released ATP mediated Ca 2+ entering the smooth muscle cells, thus inducing the sympathetic neurogenic contraction.…”