Thrombin-mediated thrombolysis prevents ischemia-reperfusion (I/R)–induced lung injury. (A) Effects of scFv/uPA-T and scFv/uPA on lung fibrin deposition induced by I/R. Thirty minutes before inducing lung I/R, mice were given an intravenous injection of 1.25 nmol scFv/uPA or scFv/uPA-T, or the same volume of PBS. Antifibrin β-chain and anti–β-actin Western blots were performed using lung fibrin extracts and total protein extracts from the same animal, respectively. The amount of fibrin in the lung was measured by densitometric scan and normalized to the amount of β-actin. The bar graph shows quantification of fibrin in each group. Fibrin deposition in PBS-treated animals was designated as 100% (n = 5–6). *P < .05; **P < .01. (B) scFv/uPA-T improves lung gas exchange. Arterial blood oxygen tension in the various cohorts was compared (n = 3–6). The dashed line represents the paO₂ in sham-operated animals. *P < .05. Error bars represent SEM.