tPA induces Akt phosphorylation in perivascular astrocytes. (A) Representative micrographs of immunogold electron microscopy analysis for pAkt in perivascular astrocytes in the area of interest-2 (AOI-2) of wild-type (i) and tPA^−/− mice (ii) 1 hour after MCAO. Bv indicates blood vessel; and bm, basement membrane. Each observation was repeated 4 times. (B) Mean Evans blue dye extravasation in wild-type mice 6 hours after reperfusion and the intraventricular injection of either vehicle (control, ■) or wortmannin (□). Results are given as a percentage compared with control-treated mice. Lines depict SD; n = 8. *P < .005 compared with control-treated mice.