Relationship of Some Blood Clotting Factors to Serotonin Release From Washed Platelets

Abstract

Thrombin in low concentration liberates all of the preformed serotonin from washed platelets suspended in plasma, saline or albumin. All of the preformed serotonin is liberated from washed platelets when they are suspended in plasma clotted with CaCl chloride and incubated for 45 minutes. About 20% is liberated when the platelets are incubated in plasma without recalcification. These results are not altered by the addition of thromboplastin or streptokinase to the samples, nor by substituting for normal plasma, plasma for patients with hemophilia or idiopathic thrombocytopenic purpura, plasma defibrinated with thrombin or heat, or chloroform plasma. The release of serotonin in these experiments can be correlated with the formation of thrombin in the samples. Complete liberation of preformed serotonin can occur without platelet disintegration, agglutination or cohesion.