Studies on metabolically depleted erythrocytes.

Erythrocytes kept outside the blood circulation undergo progressive changes in metabolism, shape and function, which was the topic of this study. For that purpose, blood anticoagulated with either heparin, citrate or EDTA was incubated at temperatures of 5°C, 22°C or 37°C for 0 h, 24 h and 48 h, respectively. A temperature- and time-dependent decrease of glucose and ATP and increase of lactate and LDH were observed. An erythrocyte swelling and echinocytic shape transformation, which was also time- and temperature-dependent, was seen. Density-separated young and old erythrocytes behaved similarly. The degree of echinocytic shape transformation correlated with the increase in blood viscosity at high shear rate. Echinocytosis was partially reversible when erythrocytes were suspended in buffer containing 0.2% albumin. This phenomenon is specific for albumin, since molecules with a similar molecular weight (dextran 70, heat shock protein, protein C) had no effect. These finding may have an impact on blood banking and transfusion medicine.