beta-Amyloid (A beta 1-40)-evoked changes in vascular reactivity are mediated via an endothelium-specific mechanism: studies using rabbit isolated aorta.
beta-Amyloid (A beta 1-40)-evoked changes in vascular reactivity are mediated via an endothelium-specific mechanism: studies using rabbit isolated aorta.
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DOI：
10.1111/j.1749-6632.1997.tb48507.x
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发表时间：
1997-09-26
影响因子：
5.2
通讯作者：
Longmore, J
中科院分区：
文献类型：
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作者：
Giokarini, T;Bonafini, L;Longmore, J
背景在阿尔茨海默病中，已经提出β-淀粉样蛋白（Aβ）沉积和血管系统的改变之间存在联系。这些改变（包括血管结构变化、血管密度降低、内皮变性和管腔闭塞）1，2可能导致脑血流量减少、血管破裂和血脑屏障完整性破坏。3最近研究表明，Aβ通过拮抗内皮依赖性舒张和增强血管收缩反应对大鼠外周血管反应性有直接影响。4，5在本研究中，我们确定了Aβ的血管效应是通过内皮特异性介导的，还是也伴随着血管平滑肌细胞内收缩/舒张机制的变化。方法从雄性新西兰白色兔（2.5-3.0 kg）获得主动脉（内皮完整或内皮剥脱）的片段，并固定在含有Kreb生理盐溶液的硅化器官浴槽中进行等长张力记录，所述硅化器官浴槽用95%氧气、5%二氧化碳（pH7.4，37 ℃）充气。在收缩实验中，获得了苯肾上腺素的累积量效曲线。对于松弛实验，用苯乙哌啶（0.2 μM，约EC 80浓度）预收缩节段，然后计算乙酰胆碱、硝普钠、毛喉素或硝苯地平的累积浓度-效应曲线。在存在Aβ肽或溶剂的情况下进行浓度-效应曲线研究。可溶性Aβ（1-40）和Aβ（40-1）的溶液（得自加州肽研究公司，USA）和Aβ-Gly 21（1-40）（获自RBI，UK）新鲜制备，显示可忽略的刚果红结合。如前所述制备聚集的Aβ（1-40）。6 μ TS浓度为0.5 μM时，可溶性Aβ（1-40）和AβGly 21（1-40）以非竞争性方式拮抗乙酰胆碱诱发的舒张，降低最大舒张反应的大小（图1）。相反，聚集的Aβ（1-40）和反向肽Aβ（40-1）没有影响（图1）。可溶性Aβ（1-40）对毛喉素、硝苯地平或硝普钠诱发的舒张或苯异丙基肾上腺素诱发的收缩均无影响（图2;所示数据来自内皮完整节段）。
BACKGROUNDIn Alzheimer's disease, it has been proposed that there is a connection between β-amyloid (Aβ) deposition and alterations in the cerebrovasculature. These alterations (including changes in angioarchitecture, reduced vascular density, endothelial degeneration and luminal occlusion) 1, 2 may result in reduced cerebral blood flow, vessel rupture and disruption of the integrity of the blood brain barrier. 3 Recently, Aβ has been shown to have direct effects on vascular reactivity in rat peripheral blood vessels by antagonizing endothelium-dependent relaxations and potentiating vasoconstrictor responses. 4, 5 In the present study, we determined whether the vascular effects of Aβ were specifically mediated via the endothelium or were also accompanied by changes in contractile/relaxant mechanisms within vascular smooth muscle cells. Rabbit isolated aorta was used as a second species in which to measure these changes.METHODSRing segments of aorta (endothelium-intact or endothelium-denuded) were obtained from male New Zealand white rabbits (2.5–3.0 kg) and mounted for isometric tension recording in siliconized organ baths containing Kreb's physiological salt solution, aerated with 95% oxygen, 5% carbon dioxide (pH 7.4, 37 C). For contractile experiments, cumulative concentration–effect curves to phenylephrine were obtained. For the relaxation experiments, the segments were pre-contracted with phenylephrine (0.2 μM, approximately an EC 80 concentration) and then a cumulative concentration–effect curve to either acetylcholine, sodium nitroprusside, forskolin, or nifedipine was calculated. Concentration–effect curve studies were performed in the presence of Aβ peptides or vehicle. Solutions of soluble Aβ (1–40) and Aβ (40–1)(obtained from California Peptide Research Inc., USA) and Aβ-Gly 21 (1–40)(obtained from RBI, UK) were freshly prepared and exhibited negligible Congo red binding. Aggregated Aβ (1–40) was prepared as previously described. 6RESULTSAt a concentration of 0.5 μM, soluble Aβ (1–40) and AβGly 21 (1–40) antagonized acetylcholine-evoked relaxations in a noncompetitive manner, reducing the size of the maximum relaxant response (Fig. 1). In contrast, aggregated Aβ (1–40) and the reverse peptide Aβ (40–1) had no effect (Fig. 1). Soluble Aβ (1–40) had no effect on relaxations evoked by forskolin, nifedipine, or sodium nitroprusside or on contractions evoked by phenylephrine both in denuded and endothelium-intact preparations (Fig. 2; data shown were obtained from endothelium-intact segments).