Summary
1. We report that NG108-15 (neuroblastoma × glioma) cells differentiated in defined serum-free media are capable of exhibiting stable automaticity (the spontaneous occurrence of regenerative action potentials) following exposure to extracellular perfusates containing NH4Cl.
2. Membrane depolarization (4–5 mV) concomitant with an increased pHi during NH4Cl exposure are followed by hyperpolarization (5–7 mV), subthreshold oscillations, and spontaneous firing after the removal of NH4Cl.
3. Cells cultured in 10% serum did not exhibit automaticity. Cells cultured in serum-free media are twice as likely to show automaticity as those cultured in reduced (1.5%) serum media.
4. We have examined factors that contribute to the events following NH4Cl exposure, namely, membrane depolarization and hyperpolarization, subthreshold oscillations, and automaticity. The inward currents activated at more negative potentials and the ionic currents associated with pronounced afterhyperpolarization in NG108-15 cells cultured in serum-free media provide a basis for the repetitive activity in general and automaticity in particular.
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References
Boron, W. F., and DeWeer, P. (1976). Intracellular pH transients in squid giant axons caused by CO2, NH3, and metabolic inhibitors.J. Gen. Physiol. 6791–112.
Bottenstein, J., and Sato, G. (1979). Growth of a rat neuroblastoma cell line in a serum-free supplemented medium.Proc. Natl. Acad. Sci. 76514–517.
Brewer, G. J., Torricelli, J. R., Evege, E. K., and Price, P. J. (1993). Optimized survival of hippocampal neurons in B-27-supplemented neurobasal, a new serum-free medium combination.J. Neurosci. Res. 35567–76.
Brodwick, M. S., and Eaton, D. C. (1978). Sodium channel inactivation in squid axon is removed by interal pH or tyrosine specific reagents. Science2001494–1496.
Christian, C. N., Nelson, P. G., Peacock, J., and Nirenberg, M. (1977). Synapse formation between two clonal cell lines.Science 196995–998.
Clay, J. R. (1990).I K inactivation in squid axons is shifted along the voltage axis by changes in intracellular pH.Biophys. J. 58797–801.
Clay, J. R., Kowtha, V. C., and Krebs, K. E. (1990). On the mechanism underlying spontaneous firing in squid giant axons with elevated intracellular pH.20th Annu. Soc. Neurosci. Meet. 20361.
Kowtha, V. C., Quong, J. N., Bryant, H. J., and Stenger, D. A. (1993). Comparative electrophysiological properties of NG108-15 cells in serum-containing and serum-free media.Neurosci. Lett. 164129–33.
Krauthamer, V. (1993). Metabolically blocked neuroblastoma cells: Changes in intracellular calcium, esterase activity, dye exclusion, and morphology.In Vitro Toxicol. 6109–116.
Maccaferri, G., Mangoni, M., Lazzari, A., and DiFrancesco, D. (1993). Properties of the hyperpolarization-activated current in rat hippocampal slices in vitro.J. Neurophysiol. 692129–2136.
McCormick, D. A., and Pape, H.-C. (1990). Properties of a hyperpolarization-activated cation current and its role in rhythmic oscillation in thalmic relay neurons.J. Physiol. 431291–318.
Moody, W. J. (1983). Intracellular pH regulation and cell excitability. InBasic Mechanisms of Neuronal Hyperexcitability (T. Jasper and N. van Gelder Eds.), Alan Liss, New York.
Perkins, K. L., and Wong, R. K. S. (1995). Intracellular OX-314 blocks the hyperpolarization-activated inward current Iq in hippocampal CA1 pyramidal cells.J. Neurophysiol. 73911–915.
Tolkovsky, A. M., and Richards, C. D. (1987). Na+/H+ exchange is the major mechanism of pH regulation in cultured sympathetic neurons: Measurements in single cell bodies and neurites using a fluorescent pH indicator.J. Neurosci. 221093–1102.
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Kowtha, V.C., Bryant, H.J., Krauthamer, V. et al. Spontaneous firing of NG108-15 cells induced by transient exposure to ammonium chloride. Cell Mol Neurobiol 16, 1–9 (1996). https://doi.org/10.1007/BF02578382
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DOI: https://doi.org/10.1007/BF02578382