Supraphysiologic level but not physiologically elevated sEPCR can exaggerate the coagulant response to factor Xa/PCPSPE challenge. (A) Levels of TAT complex in the plasma of Procr^+/− mice (n = 14), Procr^s/+ mice (n = 6), Procr ^+/+ mice (n = 20), and Procr^+/+ mice with 20 μg sEPCR (n = 4). The mice used for the experiments included Procr^+/− mice and their Procr^+/+ littermates, and Procr^s/+ mice and their Procr^+/+ littermates. The 2 groups of Procr^+/+ mice exhibited almost the same results. Therefore, the results of Procr^+/+ mice were combined together. (B) Platelet counts in the blood. (C) APC/TAT ratios in the plasma. (D) APC levels in the plasma. Results are presented as mean ± SD. Mice with supraphysiologic sEPCR exhibit a significantly higher TAT level, lower platelet count, and lower APC/TAT ratio compared with mice without sEPCR supplementation after factor Xa/PCPSPE challenge (P < .01).