Effect of tPA on locomotor activity and cerebral edema following MCAO. (A) Mean locomotor activity at 6, 24, and 48 hours after MCAO in wild-type (○) or tPA^−/− mice (▪ and ▴); tPA^−/− mice treated with murine tPA immediately after MCAO (▴). Error bars describe standard error of the mean; n = 6; *P < .05 when tPA^−/− mice are compared with wild-type mice or with tPA^−/− animals treated with tPA. (B) Evans blue dye extravasation in the same group of animals as panel A 48 hours after MCAO. Error bars describe standard error of the mean. *P < .01 when tPA^−/− mice are compared with wild-type animals; †P < .05 when tPA^−/− mice treated with recombinant tPA are compared with untreated tPA^−/− mice. The pictures correspond to one representative brain in each experimental group. The blue staining is apparent in areas with increase in blood-brain barrier permeability (arrows).