PLASMA PIVKA PROTEINS IN RABBITS GIVEN WARFARIN

The presence of partially carboxylated forms of the vitamin K dependen t coagulation factors (PIVKA) was evaluated in the plasma of rabbits t reated with warfarin. Excess antigen over activity as measured in rabb it specific assays was taken as evidence for PIVKA. Our data confirm a previous report of the absence of plasma PIVKA prothrombin. In contra st, plasma PIVKA factors VII, IX, and X were demonstrable. A striking excess of plasma factor IX antigen over activity was measured and a la rge fraction of the factor IX antigen persisted in the plasma after it s adsorption with barium citrate.