Transient increases in intracellular Ca²⁺ activate endothelium-dependent vasodilatory pathways. This process is impaired in cerebral amyloid angiopathy, where amyloid-β_(1-40) accumulates around blood vessels. In neurons, amyloid-β impairs the Ca²⁺-permeable N-methyl-D-aspartate receptor (NMDAR), a mediator of endothelium-dependent dilation in arteries. We hypothesized that amyloid-β_(1-40) reduces NMDAR-elicited Ca²⁺ signals in mouse cerebral artery endothelial cells, blunting dilation. Cerebral arteries isolated from 4-5 months-old, male and female cdh5:Gcamp8 mice were used for imaging of unitary Ca²⁺ influx through NMDAR (NMDAR sparklets) and intracellular Ca²⁺ transients. The NMDAR agonist NMDA (10 µmol/L) increased frequency of NMDAR sparklets and intracellular Ca²⁺ transients in endothelial cells; these effects were prevented by NMDAR antagonists D-AP5 and MK-801. Next, we tested if amyloid-β_(1-40) impairs NMDAR-elicited Ca²⁺ transients. Cerebral arteries incubated with amyloid-β_(1-40) (5 µmol/L) exhibited reduced NMDAR sparklets and intracellular Ca²⁺ transients. Lastly, we observed that NMDA-induced dilation of pial arteries is reduced by acute intraluminal amyloid-β_(1-40), as well as in a mouse model of Alzheimer’s disease, the 5x-FAD, linked to downregulation of Grin1 mRNA compared to wild-type littermates. These data suggest that endothelial NMDAR mediate dilation via Ca²⁺-dependent pathways, a process disrupted by amyloid-β_(1-40) and impaired in 5x-FAD mice.

细胞内Ca ²⁺的短暂增加激活内皮依赖性血管舒张途径。这一过程在脑淀粉样血管病中受到损害，β-淀粉样蛋白_(1-40)在血管周围积聚。在神经元中，β淀粉样蛋白会损害 Ca ²⁺渗透性 N-甲基-D-天冬氨酸受体 (NMDAR)，后者是动脉内皮依赖性扩张的介质。我们假设淀粉样蛋白-β _(1-40)会减少小鼠大脑动脉内皮细胞中NMDAR 引发的 Ca ^{2+信号，从而减弱扩张。}使用从 4-5 个月大的雄性和雌性cdh5:Gcamp8小鼠中分离的脑动脉对通过 NMDAR ( NMDAR 火花) 的单一 Ca ²⁺流入和细胞内 Ca ²⁺瞬变进行成像。NMDAR 激动剂 NMDA (10 µmol/L) 增加内皮细胞中NMDAR 火花和细胞内 Ca ^{2+瞬变的频率；}NMDAR 拮抗剂 D-AP5 和 MK-801 可以阻止这些作用。接下来，我们测试了淀粉样蛋白-β _(1-40)是否会损害 NMDAR 引发的 Ca ²⁺瞬变。用淀粉样蛋白-β _(1-40) (5 µmol/L) 孵育的脑动脉表现出NMDAR 火花和细胞内 Ca ²⁺瞬变减少。最后，我们观察到，急性管腔内淀粉样蛋白-β _(1-40)以及阿尔茨海默氏病小鼠模型5x-FAD均观察到，NMDA 诱导的软脑膜动脉扩张与Grin1 mRNA 下调（与对照组相比）有关。野生型同窝小鼠。这些数据表明内皮 NMDAR 通过 Ca ²⁺依赖性途径介导扩张，该过程被淀粉样蛋白-β _(1-40)破坏并在5x-FAD小鼠中受损。