Further studies of the circulation with radioactive erythrocytes

Determination of the Circulating Red Cell Volume in Man by Radioactive Chromium 1

“…After three days, the red cell activity decreased by approximately 15%o compared to a similar fall after three hours when p32 tagged red cells are used (5)(6)(7)(8). The constancy of red cell tagging with Cr5' should prove of value in clinical studies where the red cell volumes may be followed throughout the course of a hospital day or where significant fluctuations in the circulating red cell volume are anticipated.…”

“…The circulating red cell volume of man and animals has been investigated heretofore by the injection of red cells labeled with the radioisotopes of iron (Fe55 and Fe59) and phosphorus (P32) (1)(2)(3)(4)(5)(6)(7)(8)(9)(10).…”

“…Radioactive phosphorus may be added in vitro to a small volume of the experimental subject's own red cells which become labeled rapidly. This technical advantage, however, is counter-balanced by the rapid phosphate exchange in vivo between the red cells and the plasma, causing the radioactivity of the tagged cells to fall significantly after one to three hours (5)(6)(7)(8).…”