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Quantitative study of calcium uptake by tumorigenic bone (TE‐85) and neuroblastoma × glioma (NG108‐15) cells exposed to extremely‐low‐frequency (ELF) electric fields
Author(s) -
Jim Kenny,
William S. Kisaalita,
G. N. Rowland,
Chi N. Thai,
T. L. Foutz
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)01029-6
Subject(s) - ionomycin , neuroblastoma , calcium , chemistry , fetal bovine serum , cell culture , intracellular , biophysics , microbiology and biotechnology , endocrinology , biology , cell , biochemistry , genetics , organic chemistry
To verify the effect of cell culture state on frequency dependent increase in proliferation as well as Ca 2+ flux across the plasma membrane, tumorigenic bone (TE‐85) and neuroblastoma × glioma (NG108‐15) cells cultured in the presence of fetal bovine serum (FBS) were exposed to capacitively coupled electric (CCEF) fields in the extremely low frequency (ELF) range of 10 to 18 Hz. [ 3 H]Thymidine incorporation and 45 Ca 2+ uptake were used as endpoints. TE‐85 cells cultured in the presence of 10% FBS did not exhibit a frequency dependent increase in proliferation in contrast to previous studies under growth arrested culture conditions, in which the cells were deprived of FBS. However, both TE‐85 and NG108‐15 cells had an increase in 45 Ca 2+ uptake in response to a 16 Hz 18.3 mV/cm CCEF. Fura‐2 digital imaging microscopy was used to verify addition of 0.5 mM La 3+ and 0.5 mM ionomycin as negative and positive controls, respectively. Imaging microscopy data was combined with 45 Ca 2+ incorporation results to quantify free intracellular calcium ([Ca 2+ ] i ) increase in response to CCEF exposure. TE‐85 [Ca 2+ ] i increased from 140 to 189–210 nM where as NG108‐15 [Ca 2+ ] i increased from 67 to 189–210 nM. These results suggested that serum deprivation may be a requirement for a frequency dependent increase in proliferation in TE‐85 cells but is not necessary for the electric field induced increase in 45 Ca 2+ uptake in both TE‐85 adn NG108 cells. The present study also represents the first demonstration of increased 45 Ca 2+ uptake by neuroblastoma and/or glioma cells in response to an electric field exposure.