Role of Platelet Factor 3 in the Hypercoagulability Induced by Pregnancy and Oral Contraceptives^[*]

Summary

As evaluated in a recording “coagulometer” the Stypven time of 16 to 19 days pregnant Holtzman rats was shorter than that of the controls solely in platelet-rich plasma but not in platelet-poor plasma collected in siliconized material when most of the platelets were removed by slow speed centrifugation (1000 G × 20 minutes). If the same blood was centrifuged at a higher speed (2000 G) the Stypven time was considerably shorter in the pregnant rats even if no platelets were left indicating that platelet factor 3 had been released in plasma during centrifugation.

Identical results were obtained in 10 women taking oral contraceptives as compared to 10 controls. Depending on whether blood was collected in siliconized glassware or not, and final determination performed in plastic or glass, the cephalin clotting time of oral contraceptives treated women was found to be longer, equal or shorter than this of the controls. When it was shorter, a comparable reduction in the Stypven time indicated that the shortening was probably due to “release” of platelet factor 3 in the platelet-poor plasma, in the course of its preparation.

^* This work was presented in part at the Illrd Congress of the International Society on Thrombosis and Haemostasis, Washington, U.S.A., August 1972.

^** Present address; Inserm, Unité 63, 22 Avenue du Doyen Lépine, 69500 Lyon-Bron-France.

• References

• 1 Dugdale M, and Masi A. T. 1971; Hormonal contraception and thromboembolic disease: Effects of the oral contraceptives on hemostatic mechanisms. A review of the literature. Journal of Chronic Diseases 23: 775.
• 2 Hardisty R. M, and Hutton R. A. 1965; The kaolin clotting time of platelet-rich plasma. A test of platelet factor 3 availability. British Journal of Haematology 11: 298.
• 3 Hardisty R. M, and Hutton R. A. 1966; Platelet aggregation and the availability of platelet factor 3. British Journal of Haematology 12: 764.
• 4 Lecompte F, and Renaud S. 1973; Influence of pregnancy and oral contraceptives on platelets in relation to coagulation and aggregation. Thrombosis et Diathesis Haemorrhagica 29: 510.
• 5 Renaud S, Gautheron P, and Rosenstein H. 1973; Platelet factor 3 activity in washed platelets. Thrombosis et Diathesis Haemorrhagica 30: 557.
• 6 Spaet T. H, and Cintron J. 1965; Studies on platelet factor 3 availability. British Journal of Haematology 11: 269.
• 7 Wolf P. 1967; The nature and significance of platelet products in human plasma. British Journal of Haematology 13: 269.