2', 3'-O-(4-benzoylbenzoyl)-ATP-mediated calcium signaling in rat glioma C6 cells: role of the P2Y(2) nucleotide receptor.

In this study, we examined the response of glioma C6 cells to 2',3'-O-(4-benzoylbenzoyl)-ATP (BzATP) and showed that the BzATP-induced calcium signaling does not involve the P2X(7) receptor activity. We show here that in the absence of extracellular Ca(2+), BzATP-generated increase in [Ca(2+)](i)via Ca(2+) release from intracellular stores. In the presence of calcium ions, BzATP established a biphasic Ca(2+) response, in a manner typical for P2Y receptors. Brilliant Blue G, a selective antagonist of the rat P2X(7) receptor, did not reduce any of the two components of the Ca(2+) response elicited by BzATP. Periodate-oxidized ATP blocked not only BzATP- but also UTP-induced Ca(2+) elevation. Moreover, BzATP did not open large transmembrane pores. What is more, a cross-desensitization between UTP and BzATP occurred, which clearly shows that in glioma C6 cells BzATP activates most likely the P2Y(2) but not the P2X(7) receptors.