JOURNAL ARTICLE

Inhibition of diet-induced atherosclerosis and endothelial dysfunction in apolipoprotein E/angiotensin II type 1A receptor double-knockout mice

Sven Wassmann, Thomas Czech, Martin van Eickels, Ingrid Fleming, Michael Böhm, Georg Nickenig
Circulation 2004 November 9, 110 (19): 3062-7
15277329

BACKGROUND: Angiotensin II type 1 (AT1) receptor activation is potentially involved in the multifactorial pathogenesis of atherosclerosis.

METHODS AND RESULTS: Apolipoprotein E-deficient (ApoE-/-) mice were crossed with AT1A receptor-deficient (AT1-/-) mice to obtain homozygous double-knockout animals (ApoE-/--AT1-/- mice). Wild-type (C57BL/6J), ApoE-/-, AT1-/-, and ApoE-/--AT1-/- mice were fed a high-cholesterol diet for 7 weeks. In contrast to wild-type and AT1-/- mice, this treatment led to severe atherosclerotic lesion formation in the aortic sinus and the aorta (oil red O staining) and to an impaired endothelium-dependent vasodilation (organ chamber experiments with isolated aortic segments) in ApoE-/- mice. In the age-matched ApoE-/--AT1-/- littermates, development of diet-induced endothelial dysfunction and atherosclerotic lesion formation was profoundly inhibited. Concomitantly, aortic release of superoxide radicals was increased 2-fold in ApoE-/- mice compared with wild-type animals, whereas aortic superoxide production was normalized in ApoE-/--AT1-/- mice (L-012 chemiluminescence). There were no significant differences in plasma cholesterol levels between ApoE-/- and ApoE-/--AT1-/- animals. Systolic blood pressure was significantly lower in ApoE-/--AT1-/- animals than in ApoE-/- mice (tail-cuff measurements). Oral treatment of ApoE-/- mice with either hydralazine or irbesartan reduced systolic blood pressure to the same level; however, only AT1 receptor antagonist treatment reduced atherosclerotic lesion formation and improved endothelial function.

CONCLUSIONS: Genetic disruption of the AT1A receptor leads to inhibition of vascular oxidative stress, endothelial dysfunction, and atherosclerotic lesion formation in ApoE-/- mice irrespective of blood pressure and plasma cholesterol levels. These results indicate a fundamental role of AT1 receptor activation in atherogenesis.

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