Cell nucleus and membrane recovery after exposure to microwaves

Cells of human buccal epithelium of six male donors were exposed to microwave radiation (frequency f = 36.64 GHz, power density W = 0.1, 1 and 4 W/m²). Exposure time was 10 seconds. The state of chromatin in cell nucleus was estimated by a number of heterochromatin granules after staining with 2% orcein in 45% acetic acid. Permeability of cell membranes was estimated by percentage of unstained cells after 5 min of staining the cells with vital dyes trypan blue (0.5%) and indigocarmine (5 mM). Cell exposure to microwaves induced chromatin condensation (increase of the number of heterochromatin granules) and increase of membrane permeability to trypan blue and indigocarmine. Isolated human buccal cells demonstrated the ability to recover after microwave exposure. The number of heterochromatin granules decreased to its initial level after 0.5 hour (W = 0.1 W/m²) and 2 hours (W = 1 and 4 W/m²) after cell exposure. Cell plasma membrane permeability recovered later — after 1 hour and 3 hours post exposure, respectively.