Impairment of Red Cell Viability by Exposure to “Excess ” Acid-Citrate Dextrose

.4 ment of red blood cell survival, it was demonstrated by Ebaugh et al. ’ that excess concentrations of chromium were toxic and impaired the viability of red blood cells. Accordingly, in order to achieve an adequate level of radioactivity when tagged blood was injected into the experimental subject, relatively large volumes ( about 30-50 ml.) of blood were used. About 10 years ago, commer-cial sources made available 100 ml. sterile bottles containing “isotonic”2 ACD solution in 10 ml. volumes. It was anticipated that about 50 ml. of blood would he added to such a bottle, after which radioactive sodium chromate solution would be added in appropriate amounts, and the mixture incubated for 30 minutes before injection into the experimental subject. This procedure was convenient, expeditious, and generally satisfactory. In more recent years it has been possible to obtain radioactive sodium chromate of greatly increased specific activity, thus permitting the use of very much smaller volumes of blood without risking the red cell damage from too high concentrations of chromium. Indeed, there are a number of advantages t