The brain infarction induced by cerebral I/R in both normotensive and Ang II hypertensive mice is largely dependent on blood cell associated-AT1aR. Twenty four hours following focal cerebral ischemia (45 min), brain tissue slices were stained with TTC and cerebral infarct volume was determined (using imaging software) from the regions not stained with the vital dye. This procedure was applied to brain sections obtained from Ang II (2000 ng/kg/min, 2 wks) or saline infused WT, AT1aR-/-, WT→WT BM chimeric and AT1aR-/-→WT BM chimeric mice. Data are shown as mean ± SE with 5-6 mice per group. * denotes p < 0.05 relative to corresponding WT mice + I/R. † denotes p < 0.05 relative to corresponding WT→WT BM chimeras.