Figure 1. Intravascular hemolysis triggers acute pulmonary thrombosis in mice.

WT mice were intravascularly (IV) administered with 150 μL dH₂O (n = 7 mice) to induce acute hemolysis and pulmonary circulation was imaged using quantitative fluorescence intravital lung microscopy (qFILM). (A) qFILM images of the same field of view (FOV) at 7 different time points are shown. t = 0 seconds (s) corresponds to time point before IV dH₂O administration and other displayed time points are relative to IV dH₂O. Pulmonary thrombosis was absent at t = 0 s. Following 150 μL dH₂O, platelet-rich thrombi (white arrowheads) sequestered in the pulmonary arteriole (t = 10 s). By t = 15 s, the thrombi were trapped in the arteriolar bottlenecks causing local impairments in blood flow. Pulmonary thrombosis started to resolve by t = 23 s and completely resolved by t = 2 minutes. Data are representative of 7 independent experiments. Platelets are shown in green and pulmonary microcirculation in purple. Asterisks denote alveoli. Dotted ellipses denote arteriolar bottlenecks. White arrow mark the direction of blood flow within the feeding arteriole. The diameter of the shown arteriole is 29 μm. Scale bar: 50 μm. Complete qFILM time series corresponding to A is shown in Supplemental Video 2. (B) Pulmonary thrombi area plotted as a function of time showing changes in the total area of platelet-rich thrombi following 150 μL IV dH₂O. Red arrow indicates pulmonary thrombi max area.