HRG deficiency is associated with accelerated thrombosis after FeCl₃-induced arterial injury. (A) Changes in blood flow after FeCl₃-induced carotid artery injury in wild-type, HRG^+/−, or HRG^−/− mice, and HRG^−/− mice given human HRG to 2 μM or saline (n = 6 or 7/group). Thrombosis was initiated by application of a 1 × 1-mm filter paper presoaked in 7.5% FeCl₃ for 1 minute to the right carotid artery. Blood flow was continuously measured before and for 30 minutes after injury. Flow measurements at the times indicated were expressed as a percentage of baseline flow. Symbols represent the mean, and the bars reflect the SE. (B) TTO values in wild-type, HRG^+/−, or HRG^−/− mice, and HRG^−/− mice given human HRG or saline. TTO was defined as the time required for blood flow to decrease to <20% of the baseline value for at least 3 consecutive minutes. TTO data are presented as a scatter diagram, where symbols represent individual values, and horizontal lines represent the mean in each of the 5 groups. Values represent mean ± SD; *P < .001 compared with wild-type mice (ANOVA, Holm-Sidak method). (C) Representative thrombus harvested from the carotid artery of a wild-type mouse 30 minutes after FeCl₃-induced injury and subjected to immunofluorescence analysis using antibodies against HRG, platelets, or fibrin, or stained with hematoxylin and eosin (H&E). Histologic sections were visualized using a ×100 objective lens fitted to an Olympus BX41 microscope equipped with a DP72 camera. Scale bars represent 100 μm.