抄録
Vitamin B_<12> content in the erythrocytes of 10 normal rabbits varied from 0.81 to 2.33 mμg per ml of the packed erythrocytes, averaging 0.16 mμg. Eighty-four per cent of vitamin B_<12> in the erythrocytes was distributed in the hemoglobin fraction and the remainder was in the stroma fraction. In the active regeneration period following phenylhydrazine anemia or anemia due to blood withdrawal, vitamin B_<12> content in both fractions of the erythrocytes was markedly increased. More remarkable increase was observed in phenylhydrazine anemia in which the regeneration was more vigorous than in anemia due to blood withdrawal. In phenylhydrazine anemia, the maximum vitamin B_<12> contents of the whole erythrocytes, the hemoglobin fraction and the stroma fraction were 6.7,6.7 and 9.1 times as high as the pre-anemic levels respectively, while in the anemia due to blood withdrawal they were 3.6,3.4 and 4.9 times, respectively. Vitamin B_<12> content in the stroma fraction reached maximum 2 days earlier than that in the hemoglobin fraction. Although protein content of the stroma was increased in the regeneration period, the vitamin content per mg protein was also increased in the period. Vitamin B_<12> contents of the whole erythrocytes and the two fractions returned to pre-anemic levels concomitantly with the convalescence of anemia. Serum total vitamin B_<12> concentration was temporarily decreased in the period in which anemia was in progress, but it was increased in the regeneration period and tended to return to pre-anemic levels in convalescence period. Changes in the free form of serum vitamin B_<12> were not significant.
