P2X Receptor Immunoreactivity in Different Arteries from the Femoral, Pulmonary, Cerebral, Coronary and Renal Circulations

Abstract

The expression of the seven P2X receptor subunits (P2X_1–7) in the rat vascular system was determined using subtype-selective antibodies. Arteries of different sizes (from arterioles to conduit vessels) from a range of vascular beds were used to give an overview of receptor expression. P2X₁ receptor immunoreactivity was detected in the smooth muscle layer of arteries. The relative level of P2X₁ receptor immunoreactivity was dependent on the size of the artery and the vascular bed; expression was highest in small and medium arteries. P2X₄ receptors were detected in all arteries; once again, the relative level of expression was dependent on the size of the artery and the vascular bed. P2X₅ receptor immunoreactivity was barely detectable in most arteries studied. P2X₇ receptor immunoreactivity was generally punctate and associated with the outer adventitial layer. Immunoreactivity for P2X₂, P2X₃ and P2X₆ receptors was not detected in arteries. These results demonstrate that arteries express multiple P2X receptor subunits and that there is a heterogeneity in the level of expression. The properties of artery P2X receptors correspond to homomeric P2X₁ receptors, and the function of P2X₄ and P2X₅ receptor subunits in arteries is unclear.

Distribution of purinergic P2X receptors in the equine digit, cervical spinal cord and dorsal root ganglia

“…P2X receptors on vascular smooth muscle cells have been firmly linked to vasoconstrictor function [16]. The P2X 7 receptor in particular has an important role in local regulation of blood flow in diverse tissues including large coronary and cerebral arteries, hepatic mesentery, and umbilical and placental vessels [17][18][19]. Vascular endothelial cells were also positive for P2X 2 and P2X 3 receptor subunits.…”

Purinergic signalling in the kidney in health and disease

“…At a protein level, however, P2X4 expression is limited to the vascular endothelium [242]. P2X7 receptors are also expressed in the healthy kidney: expression in the vascular smooth muscle and outeradventitium is very low [218], whereas functionally significant expression is observed in the endothelium [242]. Of the P2Y receptors, P2Y 1 is expressed in the endothelium of the large arteries and both afferent and efferent arterioles [375].…”

Regulation of Renal Hemodyamics by Purinergic Receptors in Angiotensin II -Induced Hypertension

“…Thus, it is possible that the renal vasoconstriction in this group may be due to blockade of P2Y1 or P2X4 receptors on the endothelial cells (Chen et al, 1996;Boyer et al, 1994;Curchill & Ellis, 1993). As above-mentioned, it has been demonstrated that P2X4 receptors are located in the endothelial cells and are linked to NO release, leading to vasodilation in dome vessels (Burnstock, 2006;Lewis, 2001;Yamamoto, 2006). Thus the blockade of P2X4 receptors by high concentrations of PPADS would decrease NO production and induce vasoconstriction (Jones et al 2000) and could explain the findings that the efferent as well the afferent arteriolar resistances were reduced.…”

“…These findings suggest an important contribution of ATP in mediating the renal vasoconstriction via activation of P2 purinergic receptors. Interestingly, P2X and P2Y receptors are expressed primarily in afferent but not in efferent arterioles; therefore, the effects of PPADS on efferent arterioles suggest the presence of additional systems that become activated after purinergic blockade in the Ang II-infused rats (Chan et al, 1998;Ichihara et al, 1998;Lambrecht, 2000;Lewis & Evans, 2001;Turner et al, 2003). In addition, PX1 and P2Y1 receptors expression in the cortex of Ang II rats was significantly higher on the immunohistochemical studies (Figure 9).…”