Clearance of ¹²⁵I-microemboli from the lungs of WT and PA-deficient mice.

(A) ¹²⁵I-microparticles were injected via the tail vein into WT mice (●); uPA^−/− mice (■); or tPA^−/− mice (▴). At the indicated times, the lungs were harvested, washed, and counted for radioactivity. The data are expressed relative to the radioactivity in the lungs 10 minutes after injection. This latter value was the same in all 3 groups. The data represent the mean plus or minus SEM of 3 independent experiments each involving 4-5 mice per time point. Data from the uPA^−/−and tPA^−/− mice are essentially superimposable when averaged over this many animals and experiments. At some time points, the error bars for WT mice are not apparent because the deviation was too small to appreciate. The triple asterisk refers to time points where the difference between the outcome in the gene deletion and WT mice reaches a statistical significance with P < .001. The insert shows residual radioactivity in tPA^−/−, uPA^−/−, and WT mice at 30 minutes compared to 10-minute controls (n = 3). (B) Autoradiography of lungs from a WT or uPA^−/− mouse 3 hours after injection of¹²⁵I-microparticles.