Deletion of Ask1 protects mice from pulmonary thromboembolism. (A) Survival curve of WT (n = 10) and Ask1^−/− (n = 15) mice after tail vein injection of a mixture of collagen (0.4 mg/kg) and epinephrine (60 mg/kg; Sigma) in 100 μL of PBS. Time of cessation of respiration (time needed to the onset of respiratory arrest that lasted at least 2-3 minutes) was recorded. (B) Pictures of mouse lungs from panel A, injected with 0.5 mL of Evans blue solution (1% in saline) into the heart 2 minutes after the onset of respiratory arrest, but while the heart was still beating or at the completion of the 10-minute observation period. Lungs were excised and photographed with a Nikon Coolpix camera. (C) Photographs of hematoxylin and eosin (H&E)–stained paraffin embedded sections of lung from panel B. Scale bar, 10 μm. (Di) Representative images of microfluidic chambers through which anticoagulated (heparin/PPACK) blood from WT and Ask1^−/− mice labeled with DiOC₆ was passed over on immobilized collagen (shear rate 800 s⁻¹) for 3 minutes. Representative images were taken under ×20 magnification with an EVOS microscope; phase contrast (upper panel) and DiOC₆ (green stained; lower panel). Percentage of surface area coverage (Dii) and fluorescence intensity (Diii) were analyzed with Image J (National Institutes of Health). Scale bar, 50 μm. (E) Quantitation of carotid occlusion time after FeCl₃ injury in platelet-depleted recipient mice receiving platelets from indicated donor mice. (F) Schematic representation of the Ask1-dependent MAPK pathway that is activated downstream of agonist receptors and partly responsible for granular secretion and integrin α_IIbβ₃ activation. Epi, epinephrine; PARs, protease-activated receptors. *P < .05; **P < .01.