ERYTHROCYTE AGGREGATION TENDENCY AND CELLULAR PROPERTIES IN HORSE, HUMAN, AND RAT - A COMPARATIVE-STUDY

Horse blood has a higher tendency to form red blood cell (RBC) aggrega tes compared with human blood, with this enhanced aggregation previous ly attributed to differences in plasma factors. Our results confirm th is observation and further indicate that washed horse RBC also have a significantly higher aggregation tendency in dextran 70 solutions (i.e ., horse RBC have a higher ''aggregability''). In contrast, the aggreg ation tendency of rat RBC, both in autologous plasma and in dextran 70 , is significantly less compared with human and horse RBC. Other rheol ogical findings for horse and rat RBC include smaller changes in RBC d eformation indexes over the same shear stress range and a lower RBC sh ape recovery time constant. Rat RBC also had higher two-phase aqueous polymer partition coefficients, suggesting a higher surface charge. Me mbrane protein analysis by sodium dodecyl sulfate-polyacrylamide gel e lectrophoresis revealed marked differences: 1) band 4.2 protein was la cking in horse RBC membranes, and 2) carbohydrate groups have differen t distributions in human, rat, and horse RBC, as indicated by differen t patterns in periodic acid-Schiff-stained protein bands. Our results clearly indicate significant differences in RBC aggregability among th e three species and indicate that cellular factors contribute importan tly to these differences. Furthermore, they suggest that systematic st udies of blood and RBC from different species should provide insight i nto the mechanism(s) of RBC aggregation.