Objective To explore the effects of pre-exposure to low intensity microwave on γ-rays induced changes of apoptosis rate, mitochondrial membrane potential (MMP) and intracellular Ca2+ concentration in human promyelocytic leukemia cells (HL-60).
Methods HL-60 cells were randomly divided into control group, microwave alone group, γ-rays alone group and combined exposure group. Microwave alone and combined exposure groups were exposed to 12 μW/cm2 microwaves, 1 hour a day, for 3 days. The combined exposure group and γ-rays alone group were subsequently exposed to 8 Gy 60Co γ-rays on the 4th day. Apoptosis was detected with Annexin V-FITC/PI double labelling method. Ca2+ concentration and MMP were detected with flow cytometry (FCM).
Results Compared with control group, apoptosis of γ-rays alone group significantly increased (P < 0.05). Apoptosis rate of combined exposure group was statistically lower than that of γ-rays alone group (P < 0.05). Compared with control group, MMP of γ-rays alone group significantly decreased (P < 0.05). MMP of combined exposure group was statistically higher than that of γ-rays alone group (P < 0.05). Compared with control group, Ca2+ concentration in γ-rays alone group significantly increased (P < 0.05). Ca2+ concentration in combined exposure group was statistically lower than that in γ-rays alone group (P < 0.05).
Conclusion Under this experimental condition, 8 Gy γ-rays increased apoptosis and Ca2+ concentrations and decreased MMP in HL-60 cells. Pre-exposure with 900 MHz, 12 μW/cm2 microwaves could significantly decrease the γ-rays damages to HL-60 cells, as evidenced by the decrease of apoptosis and Ca2+ concentrations and the increase of MMP.
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