Quantitative study of calcium uptake by tumorigenic bone (TE-85) and neuroblastoma x glioma (NG108-15) cells exposed to extremely-low-frequency (ELF) electric fields.
To verify the effect of cell culture state on frequency dependent increase in proliferation as well as Ca2+ flux across the plasma membrane, tumorigenic bone (TE-85) and neuroblastoma x 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. [3H]Thymidine incorporation and 45Ca2+ 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 45Ca2+ 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 La3+ and 0.5 mM ionomycin as negative and positive controls, respectively. Imaging microscopy data was combined with 45Ca2+ incorporation results to quantify free intracellular calcium ([Ca2+]i) increase in response to CCEF exposure. TE-85 [Ca2+]i increased from 140 to 189-210 nM where as NG108-15 [Ca2+]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 45Ca2+ uptake in both TE-85 and NG108 cells. The present study also represents the first demonstration of increased 45Ca2+ uptake by neuroblastoma and/or glioma cells in response to an electric field exposure.
Kenny
J S
JS
Biological and Agricultural Engineering Department, Driftmier Engineering Center, University of Georgia, Athens 30602, USA.
Kisaalita
W S
WS
Rowland
G
G
Thai
C
C
Foutz
T
T
D000818:Animals; D001692:Biological Transport; D001859:Bone Neoplasms; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D004273:DNA, Neoplasm / Q000096:biosynthesis*; D004560:Electricity; D005910:Glioma; D006801:Humans; D006822:Hybrid Cells; D015759:Ionomycin / Q000494:pharmacology; D007700:Kinetics; D007811:Lanthanum / Q000494:pharmacology; D009447:Neuroblastoma; D009991:Oscillometry; D012516:Osteosarcoma; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm; D015759:Ionomycin; D007811:Lanthanum; D002118:Calcium; D013936:Thymidine