Phosphorylated extracellular signal-regulated kinase
2 immunoreactivity in the walls of the middle cerebral artery
and microvessels following subarachnoid hemorrhage
(SAH). Images represent (A) sham, SAH + vehicle and SAH + U0126, 2 days after SAH; (B) sham, SAH + vehicle and SAH + U0126, 3 days after SAH; and (C) sham and SAH, 4 days after SAH. There was an increased activation of pERK1/2 in the SMCs of the MCA and microvessels (white arrows) after SAH + vehicle as compared to sham-operated rats at 2 and 3 days. Treatment with U0126 given at 6 h after induced SAH prevented the increased protein expression at 2 and 3 days. (D) Bar graph showing semiquantification of fluorescence intensity for pERK1/2 in the MCA. There was a significant increase in the expression of this protein in SAH animals as compared to sham animals at 2 and 3 days post-SAH but not at 4 days. This increase was prevented with U0126 treatment starting at 6 h. Data are presented as the mean percentage relative to sham ± SEM; n = 5. *P <0.05, **P <0.01.