Biological Effects On Cells Induced By Combination Of Microwave And γ-ray Radiation

Objective: To study biological effects on SHG44 cells combined by 900MHz microwave andγ-ray radiation.Methods: SHG44 cells were divided into four groups according to the power density of microwave(0 mw/cm2,2mw/cm2,4mw/cm2 and 6mw/cm2),named as C,M2,M4 and M6,respectively.The cells were exposed to microwave 2h/d for 3d,and then were irradiated byγ-ray (5Gy),whit four groups named as I,I+M2,I+M4 and I+M6,respectively.(1) Cellular proliferation was measured with MTT test and cloning efficiency.(2) Cell cycle and apoptosis were detected by flow cytometer.(3) SOD activity and MDA level were tested by commercial kits.(4) Expression of HSP70 gene was evaluated by RT-PCR and western blot.(5) Normal rat glial cells were cultured and cellular proliferation , apoptosis and ATPase activity were measured.(6) Ultraweak luminescence of cells was measured by the Ultraweak Luminescence Analyzer.Results: (1) Cell proliferation activity in Group M4 and M6 and cloning efficiency in all exposed groups were decreased by the microwave radiation,with a significant decrease in Group I+M4 and I+M6.Combination of Microwave andγ-ray showed synergistic effect on both cell proliferation activity and the cloning efficiency.(2) Compared to the microwave radiation groups,the percentage of G1 phase cells obviously increased in the combination groups,while that of G2 and S phase decreased.The rate of apoptosis increased with the does of microwave in the microwave radiation groups and so did the I+M4 and I+M6 Group,indicating a synergistic effect ofγ-ray and microwave.(3) The MDA level increased in Group M6 and in all combination groups,and the SOD activity decreased in Group I+M6.(4) Expression of HSP70 at both mRNA and protein levels increased slightly in the microwave exposure groups,but no interaction ofγ-ray and microwave on HSP70 expression was found.(5) Proliferation of the rat glial cell in Group I and I+M6 decreased slightly,and the ATPase activity was significantly increased.(6) Ultraweak luminescence of the exposed cells was stronger than the control cells on the first day,and returned to normal on the second day.Conclusion: Microwave andγ-ray could inhibit the proliferation of SHG44 cells with a synergistic effect,but such effect was not observed in primary rat glial cells.Ultraweak luminescence could be strengthened by microwave at early stages of exposure.