Voltage-sensitive Ca2+ channels, intracellular Ca2+ stores and Ca2+-release-activated Ca2+ channels contribute to the ATP-induced [Ca2+]i increase in differentiated neuroblastoma×glioma NG 108-15 cells

Characteristics of P2X7-Like Receptor Activated by Adenosine Triphosphate in HIT-T15 Cells

“…39 In lymphocytes, BzATP stimulated the influx of Ca 2+ from the extracellular medium without triggering the release of Ca 2+ from the internal stores. 23 Similarly, ATP stimulated the increase in [Ca 2+ ] i and membrane depolarization in HIT-T15 cells (Figs.…”

ATP‐induced [Ca2+]i changes and depolarization in GH3 cells

“…Previous studies have indicated that the activation of P2X 7 ionotropic receptors with BzATP directly opens non‐selective cation channels, leading to an increase in [Ca 2+ ] i and membrane depolarization ( Inoue & Brading, 1990 ) in other cell types, including macrophages ( Picello et al ., 1990 ), thymocytes ( Pizzo et al ., 1991 ), oocytes ( Nuttle & Dubyak, 1994 ), and neuroblastoma×NG108‐15 cells ( Brater et al ., 1999 ). Membrane depolarization activates voltage‐sensitive Ca 2+ channels (VSCC) allowing further Ca 2+ entry.…”

Stimulation of P2X7Receptors Elevates Ca2+and Kills Retinal Ganglion Cells

“…Although removal of extracellular Ca 2ϩ for 24 hours was not possible, downstream activation of voltage-dependent Ca 2ϩ channels can follow the stimulation of the P2X 7 receptor, 37 and retinal ganglion cells are known to express several voltage-dependent calcium channels including L-type calcium channels. 38 To determine whether influx of Ca 2ϩ through L-type calcium channels contributed to cell death, cells were incubated in the presence of BzATP, with and without the L-type calcium channel blocker nifedipine (50 M).…”

“…After stimulation of the P2X 7 receptor in NG 108-15 cells, influx through the P2X 7 pore itself increased Ca 2ϩ by 211 nM, whereas an additional increase of 227 nM Ca 2ϩ occurred through N-type Ca 2ϩ channels and 189 nM through L-type channels. 37 Examination of currents in rat retinal ganglion cells showed that Ͼ60% of the increase in Ca 2ϩ after stimulation with ATP was secondary to receptor activation, as removal of extracellular Na ϩ attenuated the response considerably. 14 Our ability to block cell death with nifedipine agrees with this study and suggests that a secondary influx through Ca 2ϩ channels contributed to ganglion cell death after stimulation of the P2X 7 receptor.…”