Characteristics of ATP-Induced Current Through P2X_7 Receptor in NG108-15 Cells : Unique Antagonist Sensitivity and Lack of Pore Formation

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ATP activates the mouse P2X7 receptor and induces a nonselective-cation current in NG108-15 cells. We investigated the effects of five receptor antagonists on the ATP-induced nonselective-cation current through P2X7 receptor (INS · P2X7) in NG108-15 cells. Nonselective P2 receptor antagonists, RB-2, PPADS and suramin inhibited the INS · P2X7 with IC50 values of 4.3, 53 and 40 μM, respectively. However, KN-04, which is a potent antagonist of human P2X7 receptors but is not that of rat P2X7 receptors, had only a weak blocking effect. Furthermore, oxidized-ATP (300 μM), an antagonist of the P2X7 receptor-mediated pore-formation, did not affect the INS · P2X7. Prolonged ATP application did not increase the membrane permeability to large molecules, N-methyl-<sc>D</sc>-glucamine or Yo-Pro-1, indicating that pore-formation was not promoted by the P2X7 receptor activation in NG108-15 cells. These results suggest that antagonist sensitivities and pore-forming properties of the P2X7 receptors in NG108-15 cells are different from those of other cells types.
社団法人日本薬理学会の論文
2002-04-01