Blood loss following tail clip in HB mice. (A) Tail clip assay was performed on HB mice (n = 5-8) and blood was collected for 2 minutes. FXa (450 μg/kg) or PBS was then administered via a pre-inserted jugular vein cannulus. Blood was collected for additional 10 minutes in a different tube of saline, and subsequent total blood loss (μL) was measured. (B) Five (light shaded column), 15 (medium shaded column), or 30 (dark shaded column) minutes before injury, FXa (450 μg/kg) or PBS was administered to HB mice (n = 6-20) via tail vein and total blood loss (μL) was measured after tail transection. In both panels, HB mice (PBS) or wt-mice infused with PBS (WT-PBS) served as controls. The number of animals per group is indicated in each column, and all measurements are presented as mean ± standard error of the mean (SEM). **P < .001 and *P < .05 represent WT or HB FXa-treated animals vs HB-PBS control.