P2X receptor immunoreactivity in different arteries from the femoral, pulmonary, cerebral, coronary and renal circulations.

The expression of the seven P2X receptor subunits (P2X1-7) 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. Copyright 2001 S. Karger AG, Basel