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Objective: Our goal was to identify the role of oxidative stress via activation of NAD(P)H oxidase in cerebrovascular dysfunction in aged rats.

Methods: We examined the reactivity of cerebral arterioles in adult and aged Fisher-344 rats to endothelial nitric oxide synthase (eNOS)-dependent (acetylcholine and adenosine diphosphate [ADP]) and-independent (nitroglycerin) agonists before and during application of tempol, apocynin, and diphenyleneiodonium chloride (DPI). We used Western blot to examine subunits of NAD(P)H oxidase, eNOS, and superoxide dismutase (SOD-1) in cerebral microvessels and parietal cortex. Finally, we measured superoxide production by cortex tissue in adult and aged rats.

Results: Acetylcholine-and ADP-induced, but not nitroglycerin-induced, dilatation of cerebral arterioles was impaired in aged compared to adult rats. While tempol, apocynin, and DPI did not alter responses in adults …