MICROELECTROPHORESIS OF BLOOD PLATELETS AND THE EFFECTS OF DEXTRAN*†

Abstract

The isoelectric point of saline washed human platelets suspended in citrate buffer is 4. When platelets are suspended in a solution containing human albumin, serum, gamma globulin or hemoglobin, the platelets appear to be partially coated by the protein in the surrounding medium, as evidenced by a change in the isoelectric point toward that of the protein. Platelets suspended in serum have an isoelectric point significantly different from platelets suspended in albumin solutions alone but not significantly different from platelets suspended in a solution containing gamma-globulin. Heparin produces a marked increase in the negative charge of platelets in citrate buffer. Dextran causes an alteration in the mobility and a significant lowering of the isoelectric point of platelets in citrate buffer. Our observations support the view that dextran affects the platelet surface. It is possible but unproven that this change prevents the platelets from forming a platelet thrombus in dextran treated animals.