The P2X(7) receptor mediates the uptake of organic cations in canine erythrocytes and mononuclear leukocytes: comparison to equivalent human cell types.

Abstract

We previously demonstrated that canine erythrocytes express the P2X(7) receptor, and that the function and expression of this receptor is greatly increased compared with human erythrocytes. Using (86)Rb(+) (K(+)) and organic cation flux measurements, we further compared P2X(7) in erythrocytes and mononuclear leukocytes from these species. Concentration response curves of BzATP- and ATP-induced (86)Rb(+) efflux demonstrated that canine P2X(7) was less sensitive to inhibition by extracellular Na(+) ions compared to human P2X(7). In contrast, canine and human P2X(7) showed a similar sensitivity to the P2X(7) antagonists KN-62 and Mg(2+). KN-62 and Mg(2+) also inhibited ATP-induced choline(+) up..