Nyvad Jakob, Mazur Aleksandra, Postnov Dmitry D, Straarup Marthe Simonsen, Soendergaard Asger Maare, Staehr Christian, Brøndum Emil, Aalkjaer Christian, Matchkov Vladimir V
Department of Biomedicine, Membranes, Aarhus University, Aarhus, Denmark.
Department of Biomedical Sciences, University of Copenhagen, Denmark.
J Physiol. 2017 Aug 1;595(15):5037-5053. doi: 10.1113/JP274604. Epub 2017 Jun 30.
Substantial information on rat mesenteric small artery physiology and pharmacology based on in vitro experiments is available. Little is known about the relevance of this for artery function in vivo. We here present an intravital model where rat mesenteric small artery diameters are studied under isolated and controlled conditions in situ with simultaneous measurement of blood flow. The responses of the isolated arteries vary with the anaesthetic used, and they are quantitatively but not qualitatively different from the responses seen in vitro.
Functional characteristics of rat mesenteric small arteries (internal diameter ∼150-200 μm) have been extensively studied in vitro using isometric and isobaric myographs. In vivo, precapillary arterioles (internal diameter < 50 μm) have been studied, but only a few studies have investigated the function of mesenteric small arteries. We here present a novel approach for intravital studies of rat mesenteric small artery segments (∼5 mm long) isolated in a chamber. The agonist-induced changes in arterial diameter and blood flow were studied using video imaging and laser speckle analysis in rats anaesthetized by isoflurane, pentobarbital, ketamine-xylazine, or by a combination of fentanyl, fluanison and midazolam (rodent mixture). The arteries had spontaneous tone. Noradrenaline added to the chamber constricted the artery in the chamber but not the downstream arteries in the intestinal wall. The constriction was smaller when rats were anaesthetized by rodent mixture in comparison with other anaesthetics, where responses were qualitatively similar to those reported in vitro. The contraction was associated with reduction of blood flow, but no flow reduction was seen in the downstream arteries in the intestinal wall. The magnitude of different endothelium-dependent relaxation pathways was dependent on the anaesthesia. Vasomotion was present under all forms of anaesthesia with characteristics similar to in vitro. We have established an intravital method for studying the tone and flow in rat mesenteric arteries. The reactivity of the arteries was qualitatively similar to the responses previously obtained under in vitro conditions, but the choice of anaesthetic affects the magnitude of responses.
基于体外实验，已有大量关于大鼠肠系膜小动脉生理学和药理学的信息。但对于其在体内动脉功能方面的相关性却知之甚少。我们在此介绍一种活体模型，在该模型中，大鼠肠系膜小动脉直径在原位的隔离和可控条件下进行研究，同时测量血流量。分离动脉的反应因所用麻醉剂而异，并且它们与体外观察到的反应在数量上而非质量上有所不同。
大鼠肠系膜小动脉（内径约150 - 200μm）的功能特性已在体外使用等长和等压肌动描记器进行了广泛研究。在体内，已对毛细血管前小动脉（内径<50μm）进行了研究，但仅有少数研究调查了肠系膜小动脉的功能。我们在此介绍一种用于对隔离在腔室内的大鼠肠系膜小动脉段（约5mm长）进行活体研究的新方法。使用视频成像和激光散斑分析，在通过异氟烷、戊巴比妥、氯胺酮 - 赛拉嗪或芬太尼、氟胺酮和咪达唑仑组合（啮齿动物混合剂）麻醉的大鼠中，研究激动剂诱导的动脉直径和血流量变化。动脉具有自发张力。添加到腔室内的去甲肾上腺素使腔室内的动脉收缩，但未使肠壁中的下游动脉收缩。与其他麻醉剂相比，用啮齿动物混合剂麻醉大鼠时收缩较小，其他麻醉剂的反应在质量上与体外报道的相似。收缩与血流量减少相关，但在肠壁的下游动脉中未观察到血流量减少。不同内皮依赖性舒张途径的程度取决于麻醉方式。在所有麻醉形式下均存在血管运动，其特征与体外相似。我们已经建立了一种用于研究大鼠肠系膜动脉张力和血流量的活体方法。动脉的反应性在质量上与先前在体外条件下获得的反应相似，但麻醉剂的选择会影响反应的幅度。
