Figure 7.

Plasminogen activator inhibitor‐1 (PAI‐1) restricts endogenous plasmin(ogen) activation in the lungs of Yersinia pestis ∆pla‐infected mice. (A) Immunoblot analysis of plasmin(ogen) recovered by bronchoalveolar lavage (BAL) from C57BL/6 or C57BL/6 PAI‐1 ^−/− mice inoculated with phosphate‐buffered saline (mock) or the indicated strains. The arrow indicates plasmin(ogen), and the arrowhead indicates plasmin. Numbers to the left of the blot indicate molecular masses in kilodaltons. The blot is representative of three independent experiments. (B) Quantification of active plasmin levels present in the BAL fluid as described above or purified active murine plasmin. Data are presented as relative fluorescence units (RFUs) at 120 min, and are combined from two independent experiments plated in triplicate; error bars represent standard errors of the mean. One‐way anova with Bonferroni's multiple comparison test was used to determine significance (*P ≤ 0.05, ***P ≤ 0.01). CFU, colony‐forming unit; NS, not significant.