Effects of millimeter waves on ionic currents of Lymnaea neurons

The effects of mm‐waves 60.22–62.22 GHz and 75 GHz on A‐type K+ currents and the effects of 61.22 GHz on Ca2+ currents of Lymnaea neurons were investigated using a whole‐cell voltage‐clamp technique. The open end of a rectangular waveguide covered with a thin Teflon film served as a radiator. Specific absorption rates at the waveguide outlet, inserted into physiological solution, were in the range of 0–2400 W/kg. Millimeter wave irradiation increased the peak amplitudes, activation rates, and inactivation rates of both ion currents. The changes in A‐type K+ current were not dependent on the irradiation frequency. It was shown that the changes in the amplitudes and kinetics of both currents resulted from the temperature rise produced by irradiation. No additional effects of irradiation on A‐type K+ current other than thermal were found when tested at the phase transition temperature or in the presence of ethanol. Ethanol reduced the thermal effect of irradiation. Millimeter waves had no effect on the steady‐state activation and inactivation curves, suggesting that the membrane surface charge and binding of calcium ions to the membrane in the area of channel locations did not change. Bioelectromagnetics 20:24–33, 1999. © 1999 Wiley‐Liss, Inc.