THE EFFECTS OF X RAY IRRADIATION ON THE RIBOFLAVIN METABOLISM : (I) CHANGE OF RIBOFLAVIN DISTRIBUTION IN VARIOUS TISSUES OF THE IRRADIATED RAT

Abstract

The effects of X ray whole body irradiation on the riboflavin contents in various tissues, blood and urine of adult male rats, fed with a standard diet were observed. 1) In 72 hours after a single irradiation with dose of 800 r the riboflavin concentration increased in the spleen, lungs, heart, intestines, stomach, brain and kidneys, but decreased in the skin and blood. The liver and muscle, however, had no marked changes. On the other hand, the riboflavin content iucreased in the heart and lungs, but decreased in the spleen and skin. The ratio of the ester form of riboflavin to the total lowered in general, especially in the blood and intestines, except in urine. 2) The above changes in riboflavin distribution in 72 hours after a single irradiations with various dosages varied in degree according to doses of X rays (400,600,800r). 3) Observations were made at the 24th, 48th, and 72nd hour after a single irradiation with dose of 800r. The changes of vitamin distribution were found to increase with progress of time. 4) Repeated irradiations with daily dose of 25r for 32 days caused only slight changes in the vitamin distribution. 5) From the above results, it may be considered that the changes in the riboflavin distribution in tissues, blood and urine of rats depend not only upon primary factors for X ray irradiation, such as the sensitivity of each tissue to X rays, the destruction of flavoprotein by the disturbance of DNA metabolism and the insufficiency of riboflavin metabolism in liver, but also upon the dynamics of physiological reactions to irradiation stress.