Pulsed magnetic field effects on calcium signaling in lymphocytes: Dependence on cell status and field intensity

The effect of 3-Hz, monopolar, quasi-rectangular magnetic field pulses on 45Ca2+ uptake in resting and mitogen-treated rat thymic lymphocytes was evaluated. A 30-min, non-thermal exposure to the pulsed magnetic field (Bpeak = 6.5 mT, Emax = 0.69 mV/cm, Jmax = 2.6 microA/cm2) reduced Concanavalin A-induced 45Ca2+ uptake by 45%. It was observed that (i) the induction of the 3-Hz field response depended on Ca2+ signal transduction activation; (ii) the response direction (stimulation or inhibition) depended on the level of lymphocyte mitogen responsiveness, and (iii) the field response magnitude increased with increasing magnetic field flux densities (Bpeak = 0, 1.6, 6.5 and 28 mT). Our results demonstrate field effects at Bmax nearly 10(4) greater than that of the average human environment for low-frequency magnetic fields and they are consistent with the independent results from other 3-Hz pulsed magnetic field studies with lymphocytes.