Hsp70 gene expression in mouse lung cells upon chronic gamma-irradiation.

Elevated levels of hsp70 mRNA in cells of lung, spleen and small intestine have been observed upon chronic in vivo gamma-irradiation of mice at a dose-rate of 3 cGy/day for 30 days. Changes in hsp70 gene expression in lung cells were analysed in more detail. Chronic irradiation with an accumulated dose of 48 cGy increased the amount of hsp70 mRNA at dose rates of 3 and 6 cGy/day and had no effect on hsp70 mRNA level at dose-rates of 1.2 and 12 cGy/day. An increased level of hsp70 mRNA was observed by day 7 of irradiation at a dose-rate of 3 cGy/day, was high by day 30 but by the end of the second month the amount of mRNA dropped to control values. Western blotting revealed a higher level of hsp70 protein as well, although the amount of protein increased to a lesser degree than that of mRNA.