Mesenteric Artery Contraction and Relaxation Studies Using Automated Wire Myography
Mesenteric Artery Contraction and Relaxation Studies Using Automated Wire Myography
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DOI：
10.3791/3119
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发表时间：
2011-09-01
影响因子：
1.2
通讯作者：
Awumey, Emmanuel M.
中科院分区：
文献类型：
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作者：
Bridges, Lakeesha E.;Williams, Cicely L.;Awumey, Emmanuel M.
近端阻力血管，如肠系膜动脉，对周围阻力有重大影响。这些直径在100 - 400μm之间的小血管主要根据身体的整体需求引导血液流向各个器官。大鼠肠系膜动脉直径大于100μm。肌动描记技术由马尔维（Mulvay）和哈尔彭（Halpern）首次描述，它基于贝万（Bevan）和奥舍（Osher）提出的方法。该技术提供了等长条件下小血管的信息，在此条件下可防止肌肉标本大幅缩短。由于血管产生的力以及对不同激动剂的敏感性取决于拉伸程度，根据主动张力 - 长度关系，在等长条件下进行收缩研究以防止固定钢丝的顺应性是至关重要的。由于钨丝会氧化从而影响记录的反应，所以不锈钢丝比钨丝更受青睐。该技术可用于比较固定血管由激动剂诱导的收缩，以获取血管平滑肌细胞受体正常功能的证据。我们在多项研究中表明，用苯肾上腺素收缩的离体肠系膜动脉在加入累积浓度的细胞外钙（Ca - e²⁺）时会舒张。这些发现使我们得出结论：表达G蛋白偶联的钙敏感受体（CaR）的血管周感觉神经介导了这种血管舒张反应。我们在此使用自动钢丝肌动描记法表明，来自Wistar大鼠、达尔盐敏感（DS）大鼠和达尔盐抵抗（DR）大鼠的肠系膜动脉对Ca - e²⁺的反应不同。与来自DR和DS大鼠的组织相比，Wistar大鼠的组织对Ca²⁺的敏感性更高。DS大鼠肠系膜动脉中CaR表达降低与离体预收缩动脉的Ca - e²⁺诱导的舒张减少相关。数据表明，在肾上腺素能张力增加的情况下（如高血压时发生的情况），肠系膜动脉的舒张需要CaR，并且表明达尔动物的CaR信号通路存在固有缺陷，在DS大鼠中这种缺陷更为严重。该方法可用于测定肠系膜阻力动脉及类似小血管的体外血管反应性，并且可以轻松、一致地对不同激动剂和/或拮抗剂进行并排比较。
Proximal resistance vessels, such as the mesenteric arteries, contribute substantially to the peripheral resistance. These small vessels of between 100-400 mu m in diameter function primarily in directing blood flow to various organs according to the overall requirements of the body. The rat mesenteric artery has a diameter greater than 100 mu m. The myography technique, first described by Mulvay and Halpern(1), was based on the method proposed by Bevan and Osher(2). The technique provides information about small vessels under isometric conditions, where substantial shortening of the muscle preparation is prevented. Since force production and sensitivity of vessels to different agonists is dependent on the extent of stretch, according to active tension-length relation, it is essential to conduct contraction studies under isometric conditions to prevent compliance of the mounting wires. Stainless steel wires are preferred to tungsten wires because of oxidation of the latter, which affects recorded responses(3). The technique allows for the comparison of agonist-induced contractions of mounted vessels to obtain evidence for normal function of vascular smooth muscle cell receptors.We have shown in several studies that isolated mesenteric arteries that are contracted with phenylyephrine relax upon addition of cumulative concentrations of extracellular calcium (Ca-e(2+)). The findings led us to conclude that perivascular sensory nerves, which express the G protein-coupled Ca2+-sensing receptor (CaR), mediate this vasorelaxation response. Using an automated wire myography method, we show here that mesenteric arteries from Wistar, Dahl salt-sensitive(DS) and Dahl salt-resistant (DR) rats respond differently to Ca-e(2+). Tissues from Wistar rats showed higher Ca2+-sensitivity compared to those from DR and DS. Reduced CaR expression in mesenteric arteries from DS rats correlates with reduced Ca-e(2+)-induced relaxation of isolated, pre-contracted arteries. The data suggest that the CaR is required for relaxation of mesenteric arteries under increased adrenergic tone, as occurs in hypertension, and indicate an inherent defect in the CaR signaling pathway in Dahl animals, which is much more severe in DS.The method is useful in determining vascular reactivity ex vivo in mesenteric resistance arteries and similar small blood vessels and comparisons between different agonists and/or antagonists can be easily and consistently assessed side-by-side(6,7,8).