Simultaneous application of pulsed high frequency currents and gamma-rays to cultured melanoma cells

Cells differentiated from a human metastasizing melanoma have been irradiated simultaneously with pulsed high frequency currents (27.12 MHz, 400--600 pulses/s, pulse duration 65mus, average power 25--38 Watt) (Diapulse), and gamma radiation from a Co-60 source. Simultaneous pulsed high frequency field and gamma radiation acted in a way resembling a cell-protecting mechanism, enhancing the number of surviving cells to the extent of about 15 percent as compared with the cell number scored after pure Co-60 gamma-radiation treatment. Irradiation with pure high frequency currents resulted in increasing cell death for a period of up 4 minutes; subsequently, this seemed to be almost independent of time. The number of cells which survived, as compared with the controls, was found to be approximately 80 percent, near a distance of 6.5 cm from the symmetry axis, perpendicular to the plane of the radiating element.