Millimeter wave exposure reverses TPA suppression of gap junction intercellular communication in HaCaT human keratinocytes

The effect of 30.16 GHz millimeter wave (MMW) exposure at 1.0 and 3.5 mW/cm(2) on gap junction intercellular communication (GJIC) was studied in cultured HaCaT keratinocytes, using the fluorescence recovery after photobleaching (FRAP) technique and laser confocal scanning microscopy to follow the intracellular movement of 5,6-carboxyfluorescein diacetate dye. While MMW exposure alone for 1 h at either 1.0 or 3.5 mW/cm(2) did not affect GJIC, MMW exposure in combination with 5 ng/ml TPA treatment reversed TPA induced suppression of GJIC. Exposure at 1.0 mW/cm(2) resulted in a partial reversal, and exposure at 3.5 mW/cm(2) resulted in essentially full reversal of the TPA suppression. (C) 2003 Wiley-Liss, Inc.