Biochemistry of late effects in rat lung after hemithoracic irradiation.

The right hemithorax of rats was exposed to 1 kR of roentgen rays, the animals were killed at different times, and various physiologic and biochemic parameters (DNA, protein, collagen, sialic acid, lysosomal enzymes, fibrinolytic activity, peroxides and blood flow ratio between irradiated and non irradiated lung) were determined from 1 day until 11 months after irradiation. A decrease in relative blood flow was observed from 2 weeks until 11 months, a decrease in phospholipids from one to 3 months and a decrease in fibrinolytic activity from 1 day to 11 months after irradiation. At several times a decrease in sialic acid and cathepsin D was also noted. The changes are discussed with respect to the pathogenetic mechanisms of late lung damage.

Late effects in the central nervous system. A study of biochemical alterations after local exposure of the rat brain to 2 krd.

The brain area of female rats three months of age was exposed to 2 krd of X-rays, and various biochemical parameters were retermined as well as NAD(H) in vivo fluorescence of the brain surface after time intervals from one day to 18 months. During the early period, an increase in the uptake of alpha-aminobutyrate (AIB) and a temporary depression in beta-glucuronidase and cathepsin activity followed by an activation at one month was seen. Somewhat later, acid phosphatase increases. During the intermediate period, DNA and serotonin content and AIB uptake by brain increase, whereas AIB uptake by heart and muscle decreases. A fall in sialic acid content is also noted at this time. During the late phase collagen increases, AIB uptake by brain and liver decreases. No changes were found with respect to NAD(H) fluorescence and its response to breathing of low oxygen concentrations.