ATP-regulated K + channel and cytosolic Ca 2+ mobilization in cultured rat spinal neurons

Abstract

ATP activated the K + channel responsible for outwardly rectifying currents via a P 2Y purinoceptor linked to a pertussis toxin-insensitive G-protein in cultured rat spinal neurons. The evoked currents were inhibited by a selective protein kinase C inhibitor, GF109203X, whereas a phospholipase C inhibitor, neomycin had no effect. These indicate that the currents are regulated by phospholipase C-independent protein kinase C activation. In addition, ATP enhanced intracellular free Ca 2+ concentration. The increase in intracellular free Ca 2+ concentration was inhibited by a broad G-protein inhibitor, GDPβS, but not affected by neomycin or an inositol 1,4,5-triphosphate receptor antagonist, heparin, suggesting that the cytosolic Ca 2+ mobilization is regulated by a mechanism independent of a phospholipase C-mediated phosphatidylinositol signaling. These results. thus, demonstrate that ATP has dual actions on the coupled K + channel and cytosolic Ca 2+ release.