Fig. 3. Effect of systemic dexmedetomidine (DXM; 2 and 10 μg/kg intravenously; n = 6;left ) and topical DXM (10−8m, 10−6m in the cranial window; n = 6;right ) on reactivity of cerebral pial arterioles to hypercapnia. Data are expressed as percentage change increase in diameter. Values are mean ± SD. *P < 0.05 compared with corresponding control (normal saline). †P < 0.05 compared with corresponding response to DXM 2 μg/kg or 10−8m.