Name: measurement of the pressure-volume curve in mouse lungs
Uploaded: 2015-01-27T15:00:00.000+00:00
Duration: 9 min 49 s
Description: Watch this Scientific Journal Video about Measurement of the Pressure-volume Curve in Mouse Lungs at JoVE.com

This work has been supported by NIH HL-1034.

约翰·霍普金斯大学动物护理和使用委员会批准的所有动物的协议。 1.设备复合体系建立起来，准备测量的PV曲线示于图1。 <ol><li>体积测量: <ol><li>通过使用注射泵用开关，其允许用户在到达压力极限后，迅速扭转泵产生膨胀和收缩的恒定速率。鼠标PV曲线，使用非常抹了油5毫升玻璃注射器与初始体积（前通胀）设置3毫升空气。 3毫升足够大，在几乎所有的鼠标PV曲线来衡量卷。 </li><li>测量由泵输送通过附加的线性差动变压器到泵壳体，具有一小的传感器杆连接到所述移动针筒柱塞的体积。 注意:实证手段来校正在系统中气体压缩光伏立方米下被描述RVE记录部分。 </li></ol></li><li>压力测量: <ol><li>使用标准的廉价的压力表，射程0-60厘米H 2 O（0-1 PSI）。 </li></ol></li><li>记录测量: <ol><li>为了记录PV曲线使用任何数字录音机XY能力（ 如 PowerLab系统）。设置一个信道来记录修正量信号和另一信道来记录跨肺压（PTP），以图表的PV曲线。使用一个桥前置放大器连接到主PowerLab系统来测量压力。 0-40厘米水柱2 O校准压力通道，并从0-3毫升校准音量通道。 </li></ol></li></ol> 2.修正了天然气压缩注意:这是在一个关键的初始步骤中的设置，因为随着压力的增加，气体体积减小，并且空气递送到小鼠的这样的体积会比SYR的位移越来越少英格桶。 <ol><li>关闭将光伏系统连接到肺部的活塞，因此没有气体能离开系统。开始输注，并观察是否刻录机上的校正量的信道表示任何可测量的变化，因为压力增加至约40cm 的 H 2 O.如果是这样，那么正确的，因为在接下来的步骤。 <ol><li>正确的气体压缩经验从活塞位移测量减去（ 即未修正量）比例通胀压力的一个术语。做一个PowerLab系统的信道（被称为维生素C），这显示数量减去信号系数倍的压力。 </li><li>确定公式中的系数。首先，初步猜测，打开图表记录，并启动泵。由于通胀油管是密封的，调整压力系数倍增，使Vc的通道读取零0-40厘米H 2 O.压力上升如果这样下去，向上或向下，只需调整校正系数，直到横盘在这个压力范围内。这种校正因子将始终是相同的，如果同一3毫升开始在注射器容量不改变。 </li></ol></li></ol>小鼠3实验测试<ol><li>程序小鼠PV曲线的测量结果。所有的动物协议批准了约翰·霍普金斯大学动物护理和使用委员会。 <ol><li>麻醉小鼠（C57BL / 6小鼠在6-12周龄）用氯胺酮（90毫克/千克）和赛拉嗪（15毫克/千克），并由于没有反射运动的确认麻醉。 注意:PV曲线可以在麻醉的小鼠中完成，在不到10分钟，是一个终端程序。 </li><li> Tracheostomize小鼠与18G的存根针管。通过一个小切口，在皮肤上的气管，定位气管，然后做一个小切口，在气管，可插入存根针的地方做到这一点。用线扎固定套管。 </li><li>让老鼠呼吸100％的氧气，至少4分钟。这可以是通过自主呼吸从袋中，或用换气名义上设定为0.2ml，在150次呼吸/分钟的潮气量。 </li><li>关闭气管插管，并允许3-4分钟为鼠标吸收所有的氧气。此氧气吸收过程引起的动物，并在肺11的几乎完整的脱气的死亡。通过测量与心电图电极或直接观察心跳停止确认的小鼠死亡。 </li><li>一旦肺的脱气完成并且肺容积为零时，开始充气与室内空气在所述注射器泵的肺以3毫升/分钟的速率。显示器上的数字记录的压力轨迹，并且当它到达35厘米H 2 O，反向泵浦。 </li><li>按照通缩的曲线，直到压力达到负10厘米H 2 O，而此时的气道已经崩溃，捕捉空气中的肺泡防止进一步的减排量。马上倒T他再次泵，使肺reinflate的崩溃航空公司公开赛。这种异构开放是嘈杂看通胀肢体这个第二通货膨胀的初始部分通常明显。 </li><li>当压力再次达到35厘米H 2 O，反转泵方向，并持续到2日通货紧缩肢体达到0厘米H 2 O.放气肺然后停泵。 </li><li>查看的压力和流量，并在PV曲线的PowerLab图表记录。然后分析PV曲线来检测在肺实质不同的肺病理学发生表型的改变。 </li></ol></li></ol>

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None of the authors have any financial interests that would be in conflict with the material presented in this paper.

在本文中一个简单的可重复的方法已经描述在小鼠中测定表型肺的弹性，总肺的PV曲线的经典方法。这样的曲线是有助于肺表面活性物质的发现及其在肺部提供稳定的重要性。这里，示出了如何在PV曲线也提供以测量在成年小鼠肺有关肺弹性几个变量的装置是有用的。有在所有的变量在两个常用的小鼠模型高度显著变化以产生在小鼠肺中的病理改变。以下部分简要讨论的变化中的每个所测量的变量...

鼠标是目前各种肺部疾病的主要动物模型。肺气肿或纤维化模型，基本的表型变化，最好通过测量变化肺弹性评估。虽然有许多方法测量弹性，经典方法是总压力容积（PV）曲线从残气量（RV）的测量，以总肺活量（TLC）的那个。这种测量已经取得了对成人肺部几乎所有的哺乳动物物种距今近100年1-3。这样的PV曲线也是在胎儿肺发育4-7肺表面活性物质功能的发现和了解发挥了重要作用。尽管PV曲线的重要性，因为肺的表型的测定，还没有标准的方式来执行这种测量。它已经做了简单的通过充气和放气与离散的步骤肺（等待可变的时间后，每个平衡）或泵的可以连续地充气和放气的肺。的PV曲线往往是做在零和一些用户自定义的肺活量之间的体积范围内，但报道的不同实验室每个压力容积循环的持续时间已经非常可变的，从几秒8变到2小时。一些研究者参考本总肺PV曲线为静态或准静态的，但这些都是质量方面，提供小的洞察力，并且它们在这里不使用。此外，PV曲线并没有被广泛报道，在小鼠，尽管事实上，它可以提供关于在肺结构变化的宏观效应的有用信息。 几个问题导致变异PV曲线收购，包括:通货膨胀和通货紧缩1）速度; 2）压力为游览通胀和通缩;和3）的装置，以确定一个绝对肺容积的测量。在该方法中存在这里，3毫升/分钟的速度被选为一项妥协即，成为不能太短，以反映与正常的通风，而不是太慢关联的动态弹性，以使测量不切实际的，学习大队列时尤为如此。由于标称总肺活量在C57BL / 6小鼠的健康是1.2毫升9的量级，这种速度通常允许两个完整的闭合回路的PV将在约1.5分钟完成。 在其中，PV曲线已经报道了在扩展文献中，使用的峰值充气压力一直非常可变的，从低到20变化到40厘米水柱2 O.这个变异性的一部分可能与物种，但设置的PV曲线压力上限的一个主要目标是充气肺总肺活量（TLC）或最大的肺容积。在TLC在人类是由最大的志愿工作，个人可以做出规定，但不幸的是这可能从来没有在任何动物模型中被复制。因此，在实验PV曲线的最大音量是威慑由最大压力由研究者任意设定开采。我们的目标是建立一个压力，其中所述PV曲线是平坦的，但不幸的是哺乳动物的肺PV曲线的膨胀肢是从不平坦的。所以大多数研究者设定一个压力，其中所述膨胀曲线开始变平基本上，典型30厘米H 2 O在小鼠，然而，PV曲线更为复杂与充气肢双驼峰，并且其中该膨胀肢常常仍然在30厘米水柱2 O 10急剧上升，所以30不是为一个好的结束点PV曲线。出于这个原因，我们使用35厘米的H 2 O为压力极限为鼠标PV曲线，这是在该充气四肢我们已审查所有菌株的开始变平的压力。 由于PV曲线本身很非线性的，光伏环的外观将取决于从弯道开始处的体积。一些商业通风允许用户做大型光伏循环，从初始的F钢筋混凝土，但如果将FRC体积是未知的话，是不可能解读的改变与任何病理，例如PV曲线，因为这些变化可以简单地从开始体积的变化造成的，而不是结构改变在肺中。因此，没有一个绝对量的测量，PV曲线几乎是不可能的解释，因此没有什么效用。虽然，有几种方法来测量肺容积，这些往往笨重，需要特殊的设备。在这里所描述的简单的方法，所述PV曲线的体内脱气过程后从零开始体积。 总之，本文说明了一个简单的方法，以规范肺PV曲线的测量在小鼠肺，并限定可从该曲线被链接到肺的结构来计算几个度量。的PV曲线因此提供肺功能测试具有在能够检测小鼠通讯表型的结构变化的直接应用肺疾病如肺气肿和纤维化。

<table><tbody><tr><td>Syringe pump</td><td>Harvard Apparatus</td><td>55-2226</td><td>Infuse/withdraw syringe pump</td></tr><tr><td>Pump 22 reversing switch</td><td>Harvard Apparatus</td><td>552217</td><td>Included with pump</td></tr><tr><td>Linear displacement transformer</td><td>Trans-Tek, Inc.</td><td>0244-0000</td><td></td></tr><tr><td>5 ml glass syringe</td><td>Becton Dickenson</td><td></td><td>Several other possible vendors</td></tr><tr><td>Digital recorder</td><td>ADInstruments</td><td>PL3504</td><td>Several other possible vendors</td></tr><tr><td>Bridge amp signal conditioner</td><td>ADInstruments</td><td>FE221</td><td></td></tr><tr><td>Gas tank, 100% oxygen</td><td>Airgas, Inc</td><td></td><td>Any supplier or hospital source will work</td></tr><tr><td>Pressure transducer: 0 - 1 psi&amp;nbsp;mV output</td><td>Omega Engineering</td><td>PX-137</td><td>Range &amp;asymp; 0 - 60 cm H&lt;sub&gt;2&lt;/sub&gt;O</td></tr></tbody></table>

measurement of the pressure-volume curve in mouse lungs

近几十年来鼠标已经成为了各种肺部疾病的主要动物模型。在肺气肿或纤维化模型中，必不可少的表型变化，最好是由变化在肺弹性测量评估。到最好的理解小鼠这样的病状底层的具体机制，它是必不可少的，以使功能测量能反映显影病理。虽然有许多方法测量弹性，经典方法是，总肺压力容积（PV）的曲线进行过肺容积的整个范围。这种测量已经取得了对成人肺部几乎所有的哺乳动物物种距今近100年了，这样的PV曲线也是在胎儿肺发育肺表面活性物质功能的发现和了解发挥了重要作用。不幸的是，这样的总的PV曲线还没有得到广泛报道，在小鼠，尽管事实上，它们可以提供对macrosc有用信息在肺的结构变化OPIC影响。尽管局部的PV曲线测量刚刚变化肺容积有时报道，没有绝对的体积的量度，总的PV曲线的非线性性质使得这些部分的那些非常难以解释。在本研究中，我们描述一个标准化的方法来测量总PV曲线。我们然后测试这些曲线来检测在两个常见肺病理学，肺气肿和纤维化改变小鼠肺结构的能力。结果显示，与这些疾病预期的结构性变化一致的几个变量显著的变化。小鼠肺PV曲线的该测量从而提供了一种简单的装置来监视随时间变化的病理生理改变和治疗程序的潜在影响的进展。

虽然为光伏曲线的步骤中演示了仅用于控制健康小鼠的视频中，我们检查了PV曲线来检测小鼠的功能和病理变化与两个不同的常见病症，肺气肿和纤维化的能力。这些传统车型的详细信息在其他地方12,13描述。很简单，麻醉用3％异氟醚后肺气肿是由3个或6ü猪胰弹性蛋白酶灌输到气管引起的，研究3周后，和纤维化是由0.05ü博莱霉素灌输到气管引起的，在此之后的研究2周侮辱。 <p class="jov...

Watch this Scientific Journal Video about Measurement of the Pressure-volume Curve in Mouse Lungs at JoVE.com

Measurement of the Pressure-volume Curve in Mouse Lungs

Here we present a protocol to simply and reliably measure the lung pressure-volume curve in mice, showing that it is sufficiently sensitive to detect phenotypic parenchymal changes in two common lung pathologies, pulmonary fibrosis and emphysema. This metric provides a means to quantify the lung&#8217;s structural changes with developing pathology.

在小鼠肺压力容积曲线的测量

In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential ...

measurement-of-the-pressure-volume-curve-in-mouse-lungs

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18.5K 次观看.  Johns Hopkins University. Here we present a protocol to simply and reliably measure the lung pressure-volume curve in mice, showing that it is sufficiently sensitive to detect phenotypic parenchymal changes in two common lung pathologies, pulmonary fibrosis and emphysema. This metric provides a means to quantify the lung’s structural changes with developing pathology.

视频: Measurement of the Pressure-volume Curve in Mouse Lungs

Pressure Controlled Ventilation to Induce Acute Lung Injury in Mice

Murine models are extensively used to investigate acute injuries of different organs systems (1-34). Acute lung injury (ALI), which occurs with prolonged mechanical ventilation, contributes to morbidity and mortality of critical illness, and studies on novel genetic or pharmacological targets are areas of intense investigation (1-3, 5, 8, 26, 30, 33-36). ALI is defined by the acute onset of the disease, which leads to non-cardiac pulmonary edema and subsequent impairment of pulmonary gas exchange (36). We have developed a murine model of ALI by using a pressure-controlled ventilation to induce ventilator-induced lung injury (2). For this purpose, C57BL/6 mice are anesthetized and a tracheotomy is performed followed by induction of ALI via mechanical ventilation. Mice are ventilated in a pressure-controlled setting with an inspiratory peak pressure of 45 mbar over 1 - 3 hours. As outcome parameters, pulmonary edema (wet-to-dry ratio), bronchoalveolar fluid albumin content, bronchoalveolar fluid and pulmonary tissue myeloperoxidase content and pulmonary gas exchange are assessed (2). Using this technique we could show that it sufficiently induces acute lung inflammation and can distinguish between different treatment groups or genotypes (1-3, 5). Therefore this technique may be helpful for researchers who pursue molecular mechanisms involved in ALI using a genetic approach in mice with gene-targeted deletion.

A murine model for ventilator induced lung injury is an important tool to study an acute lung injury in vivo. Here, we report an easy applicable in situ model for acute lung injury using high-pressure mechanical ventilation to induce acute failure of the lung.

压力控制通气诱导小鼠急性肺损伤

Murine models are extensively used to investigate acute injuries of different organs systems (1-34). Acute lung injury (ALI), which occurs with prolonged ...

科研

医学

Right Ventricular Systolic Pressure Measurements in Combination with Harvest of Lung and Immune Tissue Samples in Mice

The function of the right heart is to pump blood through the lungs, thus linking right heart physiology and pulmonary vascular physiology. Inflammation is a common modifier of heart and lung function, by elaborating cellular infiltration, production of cytokines and growth factors, and by initiating remodeling processes 1.
Compared to the left ventricle, the right ventricle is a low-pressure pump that operates in a relatively narrow zone of pressure changes. Increased pulmonary artery pressures are associated with increased pressure in the lung vascular bed and pulmonary hypertension 2. Pulmonary hypertension is often associated with inflammatory lung diseases, for example chronic obstructive pulmonary disease, or autoimmune diseases 3. Because pulmonary hypertension confers a bad prognosis for quality of life and life expectancy, much research is directed towards understanding the mechanisms that might be targets for pharmaceutical intervention 4. The main challenge for the development of effective management tools for pulmonary hypertension remains the complexity of the simultaneous understanding of molecular and cellular changes in the right heart, the lungs and the immune system.
Here, we present a procedural workflow for the rapid and precise measurement of pressure changes in the right heart of mice and the simultaneous harvest of samples from heart, lungs and immune tissues. The method is based on the direct catheterization of the right ventricle via the jugular vein in close-chested mice, first developed in the late 1990s as surrogate measure of pressures in the pulmonary artery5-13. The organized team-approach facilitates a very rapid right heart catheterization technique. This makes it possible to perform the measurements in mice that spontaneously breathe room air. The organization of the work-flow in distinct work-areas reduces time delay and opens the possibility to simultaneously perform physiology experiments and harvest immune, heart and lung tissues.
The procedural workflow outlined here can be adapted for a wide variety of laboratory settings and study designs, from small, targeted experiments, to large drug screening assays. The simultaneous acquisition of cardiac physiology data that can be expanded to include echocardiography5,14-17 and harvest of heart, lung and immune tissues reduces the number of animals needed to obtain data that move the scientific knowledge basis forward. The procedural workflow presented here also provides an ideal basis for gaining knowledge of the networks that link immune, lung and heart function. The same principles outlined here can be adapted to study other or additional organs as needed.

A specific and rapid protocol to simultaneously investigate right heart function, lung inflammation, and the immune response is described as a learning tool. Video and figures describe physiology and microdissection techniques in an organized team-approach that is adaptable to be used for small to large sized studies.

右心室收缩压测量组合在小鼠的肺和免疫组织样品的收获

The function of the right heart is to pump blood through the lungs, thus linking right heart physiology and pulmonary vascular physiology. Inflammation is ...

免疫与感染

A Standardized Method for Measuring Internal Lung Surface Area via Mouse Pneumonectomy and Prosthesis Implantation

Pulmonary morphology, physiology, and respiratory functions change in both physiological and pathological conditions. Internal lung surface area (ISA), representing the gas-exchange capacity of the lung, is a critical criterion to assess respiratory function. However, observer bias can significantly influence measured values for lung morphological parameters. The protocol that we describe here minimizes variations during measurements of two morphological parameters used for ISA calculation: internal lung volume (ILV) and mean linear intercept (MLI). Using ISA as a morphometric and functional parameter to determine the outcome of alveolar regeneration in both pneumonectomy (PNX) and prosthesis implantation mouse models, we found that the increased ISA following PNX treatment was significantly blocked by implantation of a prosthesis into the thoracic cavity1. The ability to accurately quantify ISA is not only expected to improve the reliability and reproducibility of lung function studies in injured-induced alveolar regeneration models, but also to promote mechanistic discoveries of multiple pulmonary diseases.

Internal lung surface area (ISA) is a critical criterion for assessing lung morphology and physiology in lung diseases and injury-induced alveolar regeneration. We describe here a standardized method that can minimize the measurement bias for ISA in both lung pneumonectomy and prosthesis implantation mouse models.

通过小鼠肺切除术和假体植入测量内部肺表面积的标准方法

Pulmonary morphology, physiology, and respiratory functions change in both physiological and pathological conditions. Internal lung surface area (ISA), ...

发育生物学

A Simple Method of Mouse Lung Intubation

A simple procedure to intubate mice for pulmonary function measurements would have several advantages in longitudinal studies with limited numbers or expensive animal. One of the reasons that this is not done more routinely is that it is relatively difficult, despite there being several published studies that describe ways to achieve it. In this paper we demonstrate a procedure that eliminates one of the major hurdles associated with this intubation, that of visualizing the trachea during the entire time of intubation. The approach uses a 0.5 mm fiberoptic light source that serves as an introducer to direct the intubation cannula into the mouse trachea. We show that it is possible to use this procedure to measure lung mechanics in individual mice over a time course of at least several weeks. The technique can be set up with relatively little expense and expertise, and it can be routinely accomplished with relatively little training. This should make it possible for any laboratory to routinely carry out this intubation, thereby allowing longitudinal studies in individual mice, thereby minimizing the number of mice needed and increasing the statistical power by using each mouse as its own control.

This paper describes a striaghforward and efficient method of intubating mice for pulmonary function measurements or pulmonary instillation, that allows the mice to recover and be studied at later times. The procedure involves an inexpensive fiberoptic light source that directly illuminates the trachea.

一个简单的方法小鼠肺插管

A  simple procedure to intubate mice for pulmonary function measurements would  have several advantages in longitudinal studies with limited numbers or  ...

Videomorphometric Analysis of Hypoxic Pulmonary Vasoconstriction of Intra-pulmonary Arteries Using Murine Precision Cut Lung Slices

Acute alveolar hypoxia causes pulmonary vasoconstriction (HPV) - also known as von Euler-Liljestrand mechanism - which serves to match lung perfusion to ventilation. Up to now, the underlying mechanisms are not fully understood. The major vascular segment contributing to HPV is the intra-acinar artery. This vessel section is responsible for the blood supply of an individual acinus, which is defined as the portion of lung distal to a terminal bronchiole. Intra-acinar arteries are mostly located in that part of the lung that cannot be selectively reached by a number of commonly used techniques such as measurement of the pulmonary artery pressure in isolated perfused lungs or force recordings from dissected proximal pulmonary artery segments1,2. The analysis of subpleural vessels by real-time confocal laser scanning luminescence microscopy is limited to vessels with up to 50 &#181;m in diameter3.
We provide a technique to study HPV of murine intra-pulmonary arteries in the range of 20-100 &#181;m inner diameters. It is based on the videomorphometric analysis of cross-sectioned arteries in precision cut lung slices (PCLS). This method allows the quantitative measurement of vasoreactivity of small intra-acinar arteries with inner diameter between 20-40 &#181;m which are located at gussets of alveolar septa next to alveolar ducts and of larger pre-acinar arteries with inner diameters between 40-100 &#181;m which run adjacent to bronchi and bronchioles. In contrast to real-time imaging of subpleural vessels in anesthetized and ventilated mice, videomorphometric analysis of PCLS occurs under conditions free of shear stress. In our experimental model both arterial segments exhibit a monophasic HPV when exposed to medium gassed with 1% O2 and the response fades after 30-40 min at hypoxia.

Hypoxic pulmonary vasoconstriction (HPV) is an important physiological phenomenon by which at alveolar hypoxia lung perfusion is matched to ventilation. The major vascular segment contributing to HPV is the intra-acinar artery. Here, we describe our protocol for the analysis of HPV of murine pulmonary vessels with diameters of 20-100 &mu;m.

使用穆林精密切肺片对肺动脉内下氧肺血管收缩进行视频形态分析

Acute alveolar hypoxia causes pulmonary vasoconstriction (HPV) - also known as von Euler-Liljestrand mechanism - which serves to match lung perfusion to ...

Automated Measurement of Pulmonary Emphysema and Small Airway Remodeling in Cigarette Smoke-exposed Mice

COPD is projected to be the third most common cause of mortality world-wide by 2020(1). Animal models of COPD are used to identify molecules that contribute to the disease process and to test the efficacy of novel therapies for COPD. Researchers use a number of models of COPD employing different species including rodents, guinea-pigs, rabbits, and dogs(2). However, the most widely-used model is that in which mice are exposed to cigarette smoke. Mice are an especially useful species in which to model COPD because their genome can readily be manipulated to generate animals that are either deficient in, or over-express individual proteins. Studies of gene-targeted mice that have been exposed to cigarette smoke have provided valuable information about the contributions of individual molecules to different lung pathologies in COPD(3-5). Most studies have focused on pathways involved in emphysema development which contributes to the airflow obstruction that is characteristic of COPD. However, small airway fibrosis also contributes significantly to airflow obstruction in human COPD patients(6), but much less is known about the pathogenesis of this lesion in smoke-exposed animals. To address this knowledge gap, this protocol quantifies both emphysema development and small airway fibrosis in smoke-exposed mice. This protocol exposes mice to CS using a whole-body exposure technique, then measures respiratory mechanics in the mice, inflates the lungs of mice to a standard pressure, and fixes the lungs in formalin. The researcher then stains the lung sections with either Gill&#8217;s stain to measure the mean alveolar chord length (as a readout of emphysema severity) or Masson&#8217;s trichrome stain to measure deposition of extracellular matrix (ECM) proteins around small airways (as a readout of small airway fibrosis). Studies of the effects of molecular pathways on both of these lung pathologies will lead to a better understanding of the pathogenesis of COPD.

The goal of this protocol is to provide automated methods to quantify chronic lung pathologies in a murine model of COPD. The protocol includes exposing mice to cigarette smoke (CS), measuring pulmonary function, inflating the lungs, and using morphometry methods to measure emphysema and small airway remodeling in mice.

肺气肿，小气道重塑的香烟烟雾暴露小鼠自动测量

COPD is projected to be the third most common cause of mortality world-wide by 2020(1).  Animal models of COPD are used to identify molecules that ...

Characterization of the Isolated, Ventilated, and Instrumented Mouse Lung Perfused with Pulsatile Flow

The isolated, ventilated and instrumented mouse lung preparation allows steady and pulsatile pulmonary vascular pressure-flow relationships to be measured with independent control over pulmonary arterial flow rate, flow rate waveform, airway pressure and left atrial pressure. Pulmonary vascular resistance is calculated based on multi-point, steady pressure-flow curves; pulmonary vascular impedance is calculated from pulsatile pressure-flow curves obtained at a range of frequencies. As now recognized clinically, impedance is a superior measure of right ventricular afterload than resistance because it includes the effects of vascular compliance, which are not negligible, especially in the pulmonary circulation. Three important metrics of impedance - the zero hertz impedance Z0, the characteristic impedance ZC, and the index of wave reflection RW - provide insight into distal arterial cross-sectional area available for flow, proximal arterial stiffness and the upstream-downstream impedance mismatch, respectively. All results obtained in isolated, ventilated and perfused lungs are independent of sympathetic nervous system tone, volume status and the effects of anesthesia. We have used this technique to quantify the impact of pulmonary emboli and chronic hypoxia on resistance and impedance, and to differentiate between sites of action (i.e., proximal vs. distal) of vasoactive agents and disease using the pressure dependency of ZC. Furthermore, when these techniques are used with the lungs of genetically engineered strains of mice, the effects of molecular-level defects on pulmonary vascular structure and function can be determined.

The following protocol outlines the process of isolating, ventilating and instrumenting mouse lungs to measure steady or pulsatile pulmonary vascular pressure-flow relationships in order to quantify the effects of blood flow, airflow, airway changes and vascular changes on right ventricular afterload.

表征隔离，通风，和仪表小鼠肺灌注与脉动流

The isolated, ventilated and instrumented mouse lung preparation allows steady and pulsatile pulmonary vascular pressure-flow relationships to be measured ...

生物学

Evaluation of Respiratory System Mechanics in Mice using the Forced Oscillation Technique

The forced oscillation technique (FOT) is a powerful, integrative and translational tool permitting the experimental assessment of lung function in mice in a comprehensive, detailed, precise and reproducible manner. It provides measurements of respiratory system mechanics through the analysis of pressure and volume signals acquired in reaction to predefined, small amplitude, oscillatory airflow waveforms, which are typically applied at the subject's airway opening. The present protocol details the steps required to adequately execute forced oscillation measurements in mice using a computer-controlled piston ventilator (flexiVent; SCIREQ Inc, Montreal, Qc, Canada). The description is divided into four parts: preparatory steps, mechanical ventilation, lung function measurements, and data analysis. It also includes details of how to assess airway responsiveness to inhaled methacholine in anesthetized mice, a common application of this technique which also extends to other outcomes and various lung pathologies. Measurements obtained in na&iuml;ve mice as well as from an oxidative-stress driven model of airway damage are presented to illustrate how this tool can contribute to a better characterization and understanding of studied physiological changes or disease models as well as to applications in new research areas.

The present protocol provides a detailed step-by-step description of the procedures required to execute measurements of respiratory system mechanics as well as the assessment of airway responsiveness to inhaled methacholine in mice using the forced oscillation technique (flexiVent; SCIREQ Inc, Montreal, Qc, Canada).

使用强迫振动技术在小鼠呼吸系统力学评价

The  forced oscillation technique (FOT) is a powerful, integrative and translational  tool permitting the experimental assessment of lung function in mice ...

Lung Fixation under Constant Pressure for Evaluation of Emphysema in Mice

Emphysema is a significant feature of chronic obstructive pulmonary disease (COPD). Studies involving an emphysematous mouse model require optimal lung fixation to produce reliable histological specimens of the lung. Due to the nature of the lung&rsquo;s structural composition, which consists largely of air and tissue, there is a risk that it collapses or deflates during the fixation process. Various lung fixation methods exist, each of which has its own advantages and disadvantages. The lung fixation method presented here utilizes constant pressure to enable optimal tissue evaluation for studies using an emphysematous mouse lung model. The main advantage is that it can fix many lungs with the same condition at one time. Lung specimens are obtained from chronic cigarette smoke-exposed mice. Lung fixation is performed using specialized equipment that enables the production of constant pressure. This constant pressure maintains the lung in a reasonably inflated state. Thus, this method generates a histological specimen of the lung that is suitable to evaluate cigarette smoke-induced mild emphysema.

Presented here is a useful protocol for lung fixation that creates a stable condition for histological evaluate of lung specimens from a mouse model of emphysema. The main advantage of this model is that it can fix many lungs with the same constant pressure without lung collapse or deflation.

小鼠肺气肿评价持续压力下的肺固定

Emphysema is a significant feature of chronic obstructive pulmonary disease (COPD). Studies involving an emphysematous mouse model require optimal lung ...

Measuring Respiratory Function in Mice Using Unrestrained Whole-body Plethysmography

Respiratory dysfunction is one of the leading causes of morbidity and mortality in the world and the rates of mortality continue to rise. Quantitative assessment of lung function in rodent models is an important tool in the development of future therapies. Commonly used techniques for assessing respiratory function including invasive plethysmography and forced oscillation. While these techniques provide valuable information, data collection can be fraught with artefacts and experimental variability due to the need for anesthesia and/or invasive instrumentation of the animal. In contrast, unrestrained whole-body plethysmography (UWBP) offers a precise, non-invasive, quantitative way by which to analyze respiratory parameters. This technique avoids the use of anesthesia and restraints, which is common to traditional plethysmography techniques. This video will demonstrate the UWBP procedure including the equipment set up, calibration and lung function recording. It will explain how to analyze the collected data, as well as identify experimental outliers and artefacts that results from animal movement. The respiratory parameters obtained using this technique include tidal volume, minute volume, inspiratory duty cycle, inspiratory flow rate and the ratio of inspiration time to expiration time. UWBP does not rely on specialized skills and is inexpensive to perform. A key feature of UWBP, and most appealing to potential users, is the ability to perform repeated measures of lung function on the same animal.

The assessment of respiratory physiology has traditionally relied upon techniques, which require restraint or sedation of the animal. Unrestrained whole-body plethysmography, however, provides precise, non-invasive, quantitative analysis of respiratory physiology in animal models. In addition, the technique allows repeated respiratory assessment of mice allowing for longitudinal studies.

用奔放的整体体积描记测量呼吸功能的影响

Respiratory dysfunction is one of the leading causes of morbidity and mortality in the world and the rates of mortality continue to rise. Quantitative ...