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 an d the effects of 61.22 GHz on Ca2+ currents of Lymnaea neurons were investi gated using a whole-cell voltage-clamp technique. The open end of a rectang ular waveguide covered with a thin Teflon film Served as a radiator. Specif ic absorption rates at the waveguide outlet, inserted into physiological so lution, were in the range of 0-2400 W/kg. Millimeter wave irradiation incre ased the peak amplitudes, activation rates, and inactivation rates of both ion currents. The changes in A-type K+ current were not dependent on the ir radiation frequency. it was shown that the changes in the amplitudes and ki netics of both currents resulted from the temperature rise produced by irra diation. No additional effects of irradiation on A-type K+ current other th an 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 inactiv ation curves, suggesting that the membrane surface charge and binding of ca lcium ions to the membrane in the area of channel locations did not change. (C) 1999 Wiley-Liss, Inc.