The Influence of Citrate and Heparin on the Adhesiveness of Rat Platelets and Human Platelets Measuredin Vitro

Abstract

1. The influence of heparin and citrate on the platelet adhesiveness to glass of normal rat platelets and normal human platelets in whole blood has been examined in vitro. 2. When citrate in a final concentration of 5.6 mill in the rat blood was used as anticoagulant, no adhesive platelets were found. By decreasing the citrate concentration to 2.8 mM, the percentage of adhesive platelets increased to 27. 3. The total and diffusible calcium and magnesium fractions of normal rat serum were estimated. The diffusible calcium fraction was significantly lower than in human serum, whereas the other fractions did not differ from the levels found in human serum. This difference may explain the difference in platelet adhesiveness in human beings and rats when estimated in vitro, using citrate as anticoagulant. 4. When heparin in a final concentration of 4.4 I.U. per ml plasma was used as anticoagulant, 8 per cent adhesive platelets were obtained in rat blood and 42 per cent in human blood. When the heparin concentration was increased to 22 I.U. per ml plasma, the percentage of adhesive platelets increased to an average value of 34 in rat blood and 60 in human blood.