Aβ Vasoactivity in Vivo

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Abstract
Abstract: Bilateral temporoparietal hypoperfusion has been frequently observed early in the Alzheimer's disease (AD) process. The β‐amyloid (Aβ) peptide is believed to play a central role in the pathogenesis of AD. In vitro experiments have shown that freshly solubilized Aβ enhances constriction of cerebral and peripheral vessels. We proposed that in vivo, Aβ would also have vasoactive properties. To test this hypothesis, we intraarterially infused freshly solubilized Aβ1–40 in rats and observed changes in peripheral blood pressure, cerebral blood flow, and cerebrovascular resistance. We found that infusion of Aβin vivo significantly increased the blood pressure in hypotensive rats but not in normotensive and hypertensive rats. Moreover, Aβ infusion also resulted in a decreased blood flow and increased vascular resistance specifically in cerebral cortex but not in heart or kidneys. These data suggest that Aβ has a direct and specific constrictive effect on cerebral vessels in vivo, which may contribute to the cerebral hypoperfusion observed early in the AD process.