Journal
CIRCULATION
Volume 110, Issue 7, Pages 843-848Publisher
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1161/01.CIR.0000138848.58269.80
Keywords
stroke; angiotensin; ischemia; receptors; stress
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Background-The role of angiotensin II receptor subtypes was investigated in focal brain ischemia induced by middle cerebral artery (MCA) occlusion. Methods and Results-In Agtr2(+) (wild-type) mice, MCA occlusion induced focal ischemia of approximate to20% to 30% of the total area in coronal section of the brain. The ischemic area was significantly larger in angiotensin II type 2 receptor-deficient (Agtr2(-)) mice than in Agtr2(+) mice. The neurological deficit after MCA occlusion was also greater in Agtr2(-) mice than in Agtr2(+) mice. The decrease in surface cerebral blood flow after MCA occlusion was significantly exaggerated in the peripheral region of the MCA territory in Agtr2(-) mice. Superoxide production and NADPH oxidase activity were enhanced in the ischemic area of the brain in Agtr2(-) mice. An AT(1) receptor blocker, valsartan, at a nonhypotensive dose significantly inhibited the ischemic area, neurological deficit, and reduction of cerebral blood flow as well as superoxide production and NADPH oxidase activity in Agtr2(+) mice. These inhibitory actions of valsartan were weaker in Agtr2(-) mice. Conclusions-These results suggest that AT(2) receptor stimulation has a protective effect on ischemic brain lesions, at least partly through the modulation of cerebral blood flow and superoxide production.
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