放射性鉄による生体内赤血球崩壊過程に関する研究

第1編 生体内赤血球崩壊過程に於ける鉄の臓器分布竝びにその消長に就て

抄録

In pursuit of the life span curve of rabbit erythrocytes with the use of radioactive iron as the tracer, and by transfusion of 1 ml/kg labeled erythrocytes, divided into young, mature and old, into normal rabbits, the author studied changes of radioactivity in peripheral blood, and the distribution and changes of radioiron in the liver, spleen, kidneys and bone marrow after the destruction of erythrocytes in each group of animals; and obtained the following results.
1. By administering intravenous injection of Fe⁵⁹-globulin into blood-depleted anemic rabbits and then giving daily intravenous injection of 3 mg/kg non-radioactive gluferricon per day for the period between the tenth day and seventieth day after the previous injection when the radioactivity of the labeled erythrocytes in circulating peripheral blood has reached the maximum, it has been found that the maximum rate of Fe⁵⁹-utilization on the sixtieth day has declined to 28.5 per cent as compared with the maximum of 84.6 per cent in Fe⁵⁹-utili zation at the early stage of the tenth day. This proves that there is a marked inhibition on the re-utilization of iron after destruction of erythrocytes.
2. The average life span of rabbit erythrocytes calculated from the life span curve under these experimental conditions is roughly 30 days.
3. When transfusion of 1 ml/kg labeled erythrocytes divided into young, mature and old, is given to different groups of normal rabbits, the older erythrocytes disappear quickly from the circulating blood, while the rate of decrease in mature erythrocytes is relatively slower, taking generally three weeks to decrease. However, in the case of young erythrocytes the changes is most peculiar in that it rapidly decreases about 20 per cent within 24 hours after the transfusion and thereafter the decrease is slowest. In other words, those erythrocytes that have been physiologically disintegrated and disposed of are mostly older erythrocytes, but some of young ones with extremely short span of life seem to be included.
4. In the pursuit of visceral distribution of radioactive iron after the similar blood tranfusion firstly no significant difference in the distribution rate among various organs can be recognized by the age of transfused blood. As for the distributed quantity per unit of organ weight it is decidedly great in the spleen as compared with other organs. The percentage of the iron distribution by different organs is generally higher in the liver and bone marrow, followed by the spleen; and in the kidneys it is found to be in only a trace. Therefore, as for the site of physiological disposal of erythrocytes at least the spleen seems to have no special bearing but rather the liver and bone marrow seem to be closely involved in such physiological processes. Moreover, in contrast to the case where hemoglobin is loaded, no significance can at all be attributable to the kidneys as the site of erythrocyte disposal, and in the meanwhile a secondary change in iron content can be recognized in bone marrow as the hematopoietic organ.