Abstract
Summary
Rats were subjected to 700 r of whole-body X-irradiation. At intervals of 13 to 85 hours after exposure, homogenates were prepared from spleens of irradiated and control animals and separated into 4 subcellular fractions by differential centrifugation. Per mg of nitrogen, DPNH cytochrome c reductase specific activity of the homogenates from X-rayed rats was increased significantly over the control levels at 13 and 37 hours after exposure. At 85 hours, the difference was much less owing to an increased specific activity of the enzyme in the control homogenates, as well. Expressed on the basis of nitrogen, cytochrome reductase specific activities of nuclear, microsomal, and supernatant fractions after irradiation showed no striking changes as compared to control values. Specific activities of the mitochondrial fractions from spleens of irradiated animals were decreased significantly as compared to control levels. The % of total DPNH cytochrome c reductase activity recovered in the 4 fractions prepared from the spleens of irradiated and control animals was essentially the same.
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