ビタミンDの代謝実験 : (I)負荷ビタミンDの正常ネズミ体内における代謝

抄録

The concentration of vitamin D in various tissues and feces was determined at intervals following an oral administration of 1000 μg of ergocalciferol. After 24 hours, about 1/3 of the dose was detected in the body and feces, and 2/3 had been consumed. Of the vitamin detected, about 1/3 was found in the body and 2/3 in feces. After 48 hours, 7 per cent of the dose was recovered in the body and 93 per cent had been consumed. Of all the tissues, the level of the vitamin was highest in liver, amounting to about 2/3 of the total vitamin in the body. Pursuing the vitamin levels in liver after orally administering 1000 μg of ergocalciferol to rats, it was found to be highest 10 to 14 hours after the dose, about 10 per cent of the dose being contained in the organ. Thereafter it fell gradually. The vitamin levels in liver and feces after successive doses of ergocalciferol were determined and the daily fecal excretion of the vitamin was found to be about 40 per cent of the dose following successive administrations of 25 to 50 μg of the vitamin and 30 per cent following an administration of 100 μg. The fecal excretion never rose gradually with successive doses. The vitamin in liver rose by 20 per cent of the dose following administration of less than 100 μg irrespective of the amount given, whereby the body weight rose normally. With the rise of the dose aobve 500 μg, the body weight began to fall, whereas the vitamin level in liver rose markedly. Supplementation of 100 to 400 μg of α-tocopherol to 1000 μg of ergocalciferol resulted in no significant rise in the vitamin level in tissues and feces.