Effect of different anticoagulants on the labelling of red blood cells and plasma proteins with 99Tcm.

There are controversies about the effect of different anticoagulants on the labelling of blood elements with 99Tcm. Our results show that the type of anticoagulant employed to withdraw the whole blood can modify the 99Tcm labelling of red blood cells (RBC) and plasma proteins (PP). The anticoagulants ACD (citric acid, sodium citrate and dextrose solution), heparin and sodium oxalate present similar results for the 99Tcm labelling of RBC with the exception of 0.13 microM stannous chloride. In this assay oxalate provides the best RBC labelling. In addition, with ethylenediaminetetraacetic acid (EDTA) the labelling of RBC is almost always lower than with the other anticoagulants, probably due to its high chelating capacity. The anticoagulants ACD, oxalate and heparin show the same results as expected with 99Tcm labelling of PP. The lowest labelling at 13.00 microM stannous chloride in the presence of oxalate is probably due to its low chelating capacity. The results also reinforce the idea that the erythrocyte membrane exerts an important role in the regulation of stannous ion transport into RBCs.