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Circulation. 2004 Aug 17;110(7):843-8. Epub 2004 Aug 2.

Possible inhibition of focal cerebral ischemia by angiotensin II type 2 receptor stimulation.

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  • 1Department of Medical Biochemistry, Ehime University School of Medicine, Shigenobu, Onsen-gun, Ehime 791-0295, Japan.

Abstract

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 approximately 20% 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 AT1 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 AT2 receptor stimulation has a protective effect on ischemic brain lesions, at least partly through the modulation of cerebral blood flow and superoxide production.

[PubMed - indexed for MEDLINE]
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