The P2X7 receptor mediates the uptake of organic cations in canine erythrocytes and mononuclear leukocytes: comparison to equivalent human cell types

[摘要] We previously demonstrated that canine erythrocytes express the P2X₇ receptor, and that the function and expression of this receptor is greatly increased compared with human erythrocytes. Using ⁸⁶Rb⁺ (K⁺) and organic cation flux measurements, we further compared P2X₇ in erythrocytes and mononuclear leukocytes from these species. Concentration response curves of BzATP- and ATP-induced ⁸⁶Rb⁺ efflux demonstrated that canine P2X₇ was less sensitive to inhibition by extracellular Na⁺ ions compared to human P2X₇. In contrast, canine and human P2X₇ showed a similar sensitivity to the P2X₇ antagonists KN-62 and Mg²⁺. KN-62 and Mg²⁺ also inhibited ATP-induced choline⁺ uptake into canine and human erythrocytes. BzATP and ATP but not ADP or NAD induced ethidium⁺ uptake into canine monocytes, T- and B-cells. ATP-induced ethidium⁺ uptake was twofold greater in canine T-cells compared to canine B-cells and monocytes. KN-62 inhibited the ATP-induced ethidium⁺ uptake in each cell type. P2X₇-mediated uptake of organic cations was 40- and fivefold greater in canine erythrocytes and lymphocytes (T- and B-cells), respectively, compared to equivalent human cell types. In contrast, P2X₇ function was threefold lower in canine monocytes compared to human monocytes. Thus, P2X₇ activation can induce the uptake of organic cations into canine erythrocytes and mononuclear leukocytes, but the relative levels of P2X₇ function differ to that of equivalent human cell types.

[学科分类] 分子生物学，细胞生物学和基因

[关键词] Dog