The effect of 2450 MHz microwave radiation on histamine secretion by rat peritoneal mast cells

Isolated rat peritoneal mast cells actively secrete histamine in response to reaginic or chemical stimulation. Mast cells were irradiated in a waveguide microwave exposure chamber at 2450 MHz with power absorptions of 8.2 and 41.0 mW/g for periods up to 3 h. These levels of microwave absorption caused no change in the morphological characteristics or viability of the cells. Irradiated mast cells were stimulated with compound 48/80, a potent, noncytotoxic histamine releasing agent. The dose response curves showed that neither prior nor simultaneous irradiation of mast cells at 37°C affected 48/80-induced secretion. However, microwave power absorptions of 41.0 mW/g inhibited secretion at 44.0°C. Precise measurements of the effect of heat on secretion indicated that this level of inhibition could have been produced by a radiation induced increase in cell temperature between 0.4 and 0.9°C above ambient levels. Alternatively, the heat stress produced at 44°C may have sensitized the cells to the electromagnetic effects of the microwave radiation. Rat peritoneal mast cells can therefore be useful as a model for the study of functioning secretory cells during microwave irradiation and can also be used to monitor the synergistic effects of cell heating during in vitro exposure.