Environ Health PerspectEnvironmental Health Perspectives0091-6765106568531637897sc271_5_1835Research Article50-Hertz magnetic field and calcium transients in Jurkat cells: results of a research and public information dissemination (RAPID) program study.WeyH EConoverD PMathiasPToraasonMLotzW GThe National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226, USA.220001082135140

An effect on intracellular calcium continues to be proposed as a biochemical pathway for the mediation of biologic effects of electrical-power-frequency magnetic fields (MF). However, reproducible results among laboratories are difficult to attain and the characteristics of magnetic field effects on intracellular free calcium ([Ca(2+)](i)) are not well understood. We attempted to repeat the studies of Lindström et al. [Intracellular Calcium Oscillations in a T-Cell Line by a Weak 50 Hz Magnetic Field. J Cell Physiol 156:395-398 (1993)] by investigating the effect of a 1.5-G 50-Hz MF on [Ca(2+)](i) in the Jurkat lymphocyte T-cell line. Changes in [Ca(2+)](i) were determined using microscopic imaging of fura-2 loaded Jurkat cells on poly-l-lysine-coated glass coverslips. The MF was generated by a single coil constructed with bifilar wire and located in the same plane as the cells. Cells were randomly exposed for 8 min to MF, sham field (SF), or no field (NF) conditions. The exposure condition remained coded until data analysis was complete. Each exposure period was preceded by an 8-min data collection to establish a baseline for [Ca(2+)](i). After each exposure condition, cells were exposed to anti-CD3 antibody that induced a rapid increase in [Ca(2+)](i) in responsive cells; this provided a positive control. [Ca(2+)](i) was analyzed for individual cells as spatially-averaged background-corrected 340/380 nm ratios, and a [Ca(2+)](i) transient was considered significant for positive deviations from baseline of 3 [multiple] an estimate of noise in the baseline. Typically, 25-50 cells/field were viewed and approximately 50% had no [Ca(2+)](i) transients in the baseline period and also responded to positive control. Only cells responding to positive control and lacking changes in [Ca(2+)](i) during the baseline period were considered qualified for assessment during the exposure period. The incidences of [Ca(2+)](i) transients during the exposure period for two experiments (40 [multiple] objective) were 16.5, 14.6, and 14.2% for MF, SF, and NF, respectively, and were not statistically significantly different. Previous studies by Lindström et al. [Intracellular Calcium Oscillations in a T-Cell Line after Exposure to Extremely-Low-Frequency Magnetic Fields with Variable Frequencies and Flux Densities. Bioelectromagnetics 16:41-47 (1995)] showed a high response rate (92%) for exposure to 1. 5-G 50-Hz MF when individual cells were preselected for investigation. We found no such effect when examining many cells simultaneously in a random and blind fashion. These results do not preclude an effect of MF on [Ca(2+)](i), but suggest that responsive cells, if they exist, were not identified using the approaches that we used in this study.

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