Analysis of the effect of a 60 Hz AC field on histamine release by rat peritoneal mast cells

Reports have indicated effects of electromagnetic fields on inflammatory processes in vivo. To begin a systematic approach toward separating and examining the many components of such responses, we created and tested a temperature-controlled device to develop 5 mT 60 Hz magnetic fields for studies of the effects of fields on mast cells, a key component in acute inflammatory responses. Such fields have been reported to modulate cell activity, including changes in membrane function, in various systems. The magnetic field was generated using a solenoid and calibrated with an induction probe. Tests of mast cell function were determined by histamine release response to stimulation by compound 48/80, using both an "expose then test" and a "test during exposure" protocol. Aliquots not treated with 48/80 were used to evaluate field treatment effects on spontaneous histamine release. Freshly harvested rat peritoneal mast cells were exposed to the magnetic field for periods of 30 min to 2 h at 37 degrees C. They showed no significant degranulation during treatment, nor did they show reduced sensitivity to the degranulating agent 48/80. These observations are consistent with a model in which such processes are exclusively reflexive by the cells using field-independent membrane systems. This observation is very useful and was needed before examining longer term exposures in which gene expression in the cells might be influenced; this is the first such report of in vitro exposure of purified mast cells under these conditions and will further the study of the effects of electromagnetic fields on cell types active in acute inflammation.