Enhancement of the cell-killing effect of ultraviolet-C radiation by short-term exposure to a pulsed magnetic field.

PURPOSE To investigate whether low frequency pulsed magnetic field (PMF) exposures produce alterations in the cell killing induced by ultraviolet C (UVC) radiation. MATERIALS AND METHODS MCF-7 breast cancer cells of exponentially growing cultures were exposed to PMF (25 Hz, 0.75 mT) and UVC (from 6.6 J/m2 to 59.4 J/m2) in two different protocols: (a) cells were exposed to PMF for 30 min and then exposed to UVC at different doses; (b) cells were exposed to PMF for 30 min. After 15 min of the PMF exposure they were exposed simultaneously to PMF+different doses of UVC. After an additional time of 72 h of incubation, viability was measured by the neutral red stain cytotoxicity test. RESULTS Both exposure protocols produced a significant decrease in the post UVC survival at 13.2 J/m2 and 19.8 J/m2, as compared to controls. The simultaneous exposition of PMF and UVC produced an additional increment in cell killing at 26.4 J/m2, being the greater effects obtained for this second exposure protocol. CONCLUSIONS Results of the present study show that PMF in combination with UVC have the ability to augment the cell killing effects of UVC radiation. In addition, the effects appear to be greater when PMF and UVC are applied at the same time.