Abstract
Reduction in the free platelet count (FPC) and release from blood cells of platelet aggregation-causing substrate were investigated in sheared rabbit blood, using citrate an anticoagulant. Significant FPC decrease of whole blood in shear fields was observed in spite of little release of hemoglobin from blood cells. When platelet rich plasma was exposed to the same shear field, however, reduction in FPC was only slight. It was suggested that adenine nucleotides were released mainly from erythrocytes in the shear field. Released ATP was rapidly converted to ADP in plasma, and this and directly released ADP were capable of initiating the platelet aggregation.
