Time‐varying and static magnetic fields act in combination to alter calcium signal transduction in the lymphocyte

Abstract

We have tested the hypothesis that extremely low frequency (ELF) time.varying magnetic fields act in combination with static magnetic fields to alter calcium ~ignalling in the lymphocyte. Results indicate that a 60-rain exposure of thymic lymphocytes at 37 ± 0.05°C to a 16 Hz, 421 mG (42.1 /aT) magnetic field simultaneously with a colinear static magnetic field of 234 mG (23.4/aT) (a.c./d.c. field intensity ratio = 1.8) inhibits calcium influx triggered by the mitogen Concanavalin A. Significantly, resting lymphocytes do not respond to the fields, thus, only mitogen-activated cells underBoin~ calcium signalling exhibit a field response. These results indicate that signal transduction involving calcium is an important biological cottslrclbtt which operates to mediate this field interaction. Additional split field exposures show that the presence of the a.c. field or the d.c. field alone does not produce an effect. This is consistent with a proposed parametric resonance theory of interaction of low intensity magnetic fields with biological systems (L.L. Ledncv (1991) Bioelextromagnetics 12, 71-75), whlch predicts the oceurran~ of biological effects at Sl~cific values for the frequency and field intensity of the ELF and static magnetic fields.

Cellular target of weak magnetic fields: ionic conduction along actin filaments of microvilli

“…Similarly, stimulation of cells with MF frequencies apart from the active frequency windows has been shown to act as an inhibitor to prestimulated Ca 2ϩ signaling (87,95). A variety of other MF-induced physiological effects indirectly suggests the involvement of the Ca 2ϩ signal pathway (20,37,55,68,72,76,80,96,98).…”

Cytoplasmic Ca2+ oscillations in human leukemia T-cells are reduced by 50 Hz magnetic fields

“…At the cellular level, a series of experiments with B-and T-lymphocytes has supplied reliable evidence that intracellular biochemical signalling pathways, obviously related to cytoplasmic Ca 2ϩ metabolism, are perturbed by external electromagnetic fields [Conti et al, 1985a,b;Walleczek and Liburdy, 1990;Carson et al, 1990;Lyle et al, 1991;Walleczek, 1992;Cadossi et al, 1992;Walleczek and Budinger, 1992;Yost and Liburdy, 1992;Liburdy et al, 1993;Lindström et al, 1993Lindström et al, , 1995Uckun et al, 1995].…”

Dual effects of microwaves on single Ca2+‐activated K+ channels in cultured kidney cells Vero

“…Exposure of Characean alga cells to millimetre EMF causes a drastic decrease in the amplitude of Ca2*-activated C1-currents [3]. Further, extremely low frequency timevarying EMFs have been shown to affect 45Ca2+ metabolism [4][5][6], see also [1,2] for references) or increase the cytosolic free Ca 2+ concentration [7 9] in resting and mitogen-treated lymphocytes. Effects of low-level EMFs on some other Ca2+-dependent biological processes have been reported elsewhere [1,2,10].…”