Figure 2. Acute hemolysis–induced pulmonary thrombosis is αIIbβ3-dependent.

(A) WT mice were intravascularly (IV) administrated with 150 μL dH₂O to trigger acute hemolysis with or without IV administration of 10 mg/kg αIIbβ3 inhibitor (eptifibatide) 15 minutes before IV dH₂O. Pulmonary circulation was imaged using quantitative fluorescence intravital lung microscopy (qFILM). qFILM images of the same field of view (FOV) at 6 different time points are shown to assess the effect of 10 mg/kg IV eptifibatide on the development of 150 μL IV dH₂O–dependent pulmonary thrombosis. t = 0 seconds (s) corresponds to time point before and t > 0 s correspond to time points immediately following IV dH₂O administration. Pulmonary thrombosis was absent at t = 0 s. dH₂O failed to evoke pulmonary thrombosis in mouse pretreated with eptifibatide. Platelets (green) and pulmonary microcirculation (purple). Asterisks denote alveoli. White arrow marks the direction of blood flow within the feeding arteriole. The diameter of the shown arteriole is 30 μm. Scale bar: 50 μm. Also refer to Supplemental Video 3. (B) Pulmonary thrombi area plotted as a function of time for the FOV shown in A. Red arrow indicates pulmonary thrombi maximum area. (C and D) Pulmonary thrombi max area and AUC in mice with (n = 3 mice) or without (n = 7 mice) pretreatment with 10 mg/kg IV eptifibatide before 150 μL IV dH₂O. Pulmonary thrombi max area and AUC were estimated as described in Methods. Pulmonary thrombi max area and AUC were compared using Wilcoxon-Mann-Whitney test. Data are shown as mean ± SEM. *P < 0.05 when comparing with and without 10 mg/kg IV eptifibatide pretreatment.