WHOLE-BODY X-RAY-IRRADIATION TO MICE DECREASES ASCORBIC-ACID CONCENTRATION IN BONE-MARROW - COMPARISON BETWEEN ASCORBIC-ACID AND VITAMIN-E

The change in the ascorbic acid concentration in the bone marrow after whole body X-ray irradiation was compared with that in the vitamin E concentration. The ascorbic acid concentration in the bone marrow sign ificantly decreased by 30% 1 h after exposure to 3 Gy of X-rays, where as the vitamin E concentration in the bone marrow was significantly de creased 5 h after exposure, when the level of ascorbic acid was less t han 10% of that in the control. At 24 h after exposure, the ascorbic a cid concentration in the bone marrow was significantly decreased by 80 % after exposure to 0.5 Gy, whereas the vitamin E concentration was si gnificantly decreased after exposure to 1 Gy or more. In the bone marr ow, the decrease in the ascorbic acid concentration was accompanied by a marked increase in the concentration of dehydroascorbic acid, an ox idized form of ascorbic acid. X-ray irradiation did not decrease eithe r the ascorbic acid or vitamin E concentration in the serum or intesti ne. These findings suggest that the bone marrow is more highly suscept ible to oxidative damage by radiation and that ascorbic acid plays an important defense role against it. On Day 8 after irradiation, the dec reases in the vitamin E and ascorbic acid concentrations in the bone m arrow showed recovery after exposure to 3 Gy, but not after the exposu re to 6 Gy.