Acute infusion of tPA (within 2 hours after photoactivation) reduces the infarct size in T+RB-PTS model. (A) The representative TTC-stained brain slices from mice receiving the vehicle or 10 mg/kg tPA at the indicated time after T+RB-PTS. Quantification showed more than 50% reduction of the infarct size in 0.5-hour tPA-treated (6.7 ± 2.1 mm³; n = 9; P < .05 by 1-way analysis of variance), 1-hour tPA-treated (4.6 ± 1.0 mm³; n = 10; P < .01), and 2-hour tPA-treated (6.4 ± 1.5 mm³; n = 8; P < .05) group, but not in the 6-hour tPA-treated group (15.2 ± 3.1 mm³; n = 7), compared with the vehicle-treated group (14.8 ± 2 mm³; n = 19). Normal distribution of the infarct size in each group was ascertained by the Komogorov-Smirnov normality test. (B) The representative images of brain surface in mice treated by vehicle, 1-hour tPA, or 6-hour PA at 24 hours after T+RB-PTS. Note the more pronounced hemorrhage spot (indicated by arrow) in the MCA-supplying territory in the mice that received the delayed, 6-hour tPA treatment. Quantification of cerebral hemorrhage indicated a higher content of hemoglobin in 6-hour tPA photothrombosis (9.6 ± 0.9 μL; n = 7) than in the vehicle (4.0 ± 0.5 μL; n = 5) or 1-hour tPA-treated (6.2 ± 0.4 μL; n = 3) groups.