Dicumarol Therapy and Platelet Turnover

¹ From the Sunnybrook Hospital, Department of Veterans Affairs, Toronto, Canada

Platelet survival and turnover were studied by the use of diisopropyl fluorophosphate, which contains phosphorus as P³² (DFP³²)in atherosclerotic male subjects. Twenty-nine were given dicumarol in doses sufficient to diminish platelet function in vitro and 31 were used as controls. Platelet survival was prolonged and platelet turnover was decreased by dieumarol therapy. Of the coagulation tests, the platelet adhesive index showed the best correlation with platelet turnover. These findings indicate that platelet function in vitro and in vivo is diminished by adequate dicumarol therapy. Evidence is presented that the survival of the platelet, at least in the atherosclerotic subject, is largely determined by factors external to the platelet, among which the activity of the coagulation mechanism is important.