这项工作是由德意志研究联合会（B＆K 196"Signaltransduktion北adaptativen UND maladaptiven kardialen改建-Prozessen"，FR 1638 / 1-2）以及由DZHK（德国中心心血管研究，健康研究的德国中心的部分支持，这是一个BMBF（德国教育和研究部的）行动）。

注:分离过程的基本步骤示于图1中的所有步骤都在下面详细描述的协议。乳头肌隔离，安装在器官浴室，采集和分析是在一个连续的和强制性的时间表进行。 所有的动物实验均按照有关保护动物的有德国法律进行，并批准了海德堡大学的伦理审查委员会。 1.准备仪表<ol><li>对于收缩测量使用多节器官浴设置。 离体收缩器官浴中设置的组件示于图2。 注意:为尽量减少的时间制备的乳头肌和实验方案的开始之间的时间量，建立设备和事先准备缓冲器收集实验tissue.This provid上课的时间，该组织保持生存能力进行实验的最大量。 </li><li>启动计算机和数据采集设备。打开器官浴热（预设为32℃），并允许单位预先设定的温度。 </li><li>准备采集设备。启动中提到的软件手册记录数据。 </li><li>检查，并进行校准（如有必要）在每个通道上，零所有通道从各自的力换能器（与该信道相关联）提供的电信号标准化到由经认证的重量供给2克力。 </li><li>开启气体供给（95％O 2/5％CO 2）到器官浴室中。连续气在整个协议的所有测量室。 </li></ol> 2.准备缓冲区和生理解决方案<ol><li>准备一个的Krebs-Henseleit缓冲溶液以达到最终浓度为119毫摩尔NaCl; 25毫米的NaHCO 3; 4.6毫米氯化钾; 11MM葡萄糖; 1毫米的Na-Pyruvate; 1.5毫米氯化钙2; 1.64毫米硫酸镁 ; 1.18毫KH 2 PO 4和调节pH值至7.4（见表1的生理溶液）。 </li><li>制备单独的Krebs-Henseleit缓冲溶液如步骤2.1中所述用另外30毫2,3-丁二酮单肟（BDM）和50的IE肝素/毫升隔离期间使用。凉溶液至4℃（见表1制备的溶液）。缺血模拟，如表1中所述制备缺血溶液。 </li><li>对于钙离子的协议-依赖性收缩， 钙离子加入到的Krebs-Henseleit缓冲溶液到请求的最终浓度。 注意:它直接使用前准备这些解决方案，并与卡波盖斯以避免Calciumcarbonate沉淀。使用前Prewarm解决方案，以32℃。 </li></ol> 3.准备的乳头切除术过程中使用的冲气管道和解剖菜<ol><li>连接软气唱管（外径2-4毫米），气体连接（100％的氧气，卡波备选地）与专家工作。 </li><li>创建冲气管解剖盘内配合的封闭环。穿刺放气管数次，一个连续鼓泡是有保证的。此放气管可多次使用。 </li><li>制备夹层菜与硅弹性体在底部（0.5厘米厚），以使销可以卡到其中。此菜可多次使用。 </li></ol> 4.分离的小鼠左前乳头肌注:在启动乳头肌的隔离前，检查煤气管道是畅通无阻的。 <ol><li>准备器官浴设置为启动乳头肌的准备之前提到的协议部分1-3。制备所有溶液在实验当天。 </li><li>颈椎脱位accordi牺牲鼠标（约8-12周龄）NG专家的工作和机构准则。 </li><li>通过固定前爪固定在背侧位置的动物和后爪上的夹层板，通过与锋利的骨剪刀肋切割打开两侧的胸腔侧，然后切断与一个横向切口隔膜。取出心包。现在的心脏和主动脉的访问。 </li><li>修复钝钳的心脏上的血管共干靠近心脏，迅速分开心脏与肺部剪刀和周围的组织。 </li><li>跳动的心脏转移至培养皿装有充以氧（步骤2.2）中的冷却溶液制备。让心脏跳动，并通过触摸心尖钳刺激心脏收缩轻声。 </li><li>一旦该心脏完全exsanguinous，其传输到解剖盘充满冷却制备溶液（步骤2.2）和通入O 2。从这个步骤上使用立体显微镜。 </li><li>修复老天室温通过右心室使心脏从背部可见（右心室位于右侧，从运营商的观点）一个小针。 </li><li>采用显微剪刀分开两个心房的房室水平，切从心室连接组织并丢弃。通过从AV-阀级到心脏，避免任何机械压力的顶点室壁执行剪切。 </li><li>打开心室和修复左路游离壁用钳子，因此具有一起来看看这两个左心室乳头肌。 </li><li>略切去上左前乳头肌的两侧保持在乳头肌制备瓣膜帆的一部分的心室组织的横向和避免接触或拉伸乳头肌尽可能。解剖从乳头肌的其余室壁组织。 </li><li>在乳头肌准备两侧安装丝线（7/0，指标0.5）aration，一个在瓣膜帆，一个在肌肉部分。修复准备在器官浴室充满器官浴的解决方案，并通入卡波，温度32℃的建议。 </li></ol> 5.平衡乳头肌和刺激<ol><li>在器官浴中的固定后立即刺激乳头肌制备的矩形脉冲（2毫秒持续时间和100mA的电流）在1赫兹的刺激频率。 </li><li>确保器官浴溶液的频繁变化，或者通过连续变化或根据所使用的器官浴类型的设置频繁地手动改变（每5分钟）。 </li><li>逐步提高预紧直到最大抽搐力达。后面没有进一步增强在抽搐力预紧的增加时，最大抽搐力达到。 </li><li>平衡后的45-60分钟，开始实验方案。 </li></ol>注意:下面列出的实验方案包括标准的机动生理和病理条件下心肌收缩的特点。在代表节中，我们还详细示出代表性的结果说明这些协议（也见表2）。 <ol><li>记录和试验方案分析<ol><li>对于记录，使用合适的软件，有足够的时间分辨率（采集率≥1kHz时）。 </li><li>分析参数，包括抽搐力的振幅（高度），达峰时间张力（TTP）和半数最大松弛时间（R 50 / TFALL，分别）中提到的软件程序（如实施例图表的ADInstruments 5.5， 参见图4）。 </li></ol></li></ol>

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作者宣称，他们有没有竞争的财务权益。

在这个手稿，我们描述的方法来研究的鼠的乳头肌收缩力在体外可被用来回答有关心脏生理和病理小鼠几个科学问题以及支持的转基因品系的分析和新药物的方法的发现治疗心脏功能障碍。我们示出了使用这种方法来评估的心肌收缩性生理，病理和药理性质（参照图3）。这里未示出的其它应用包括使用不同的药理学试剂的细胞内途径的评价（参见12）。 </p...

像离子通道参照它们的作用为心脏收缩蛋白的调查是必不可少的发现不同的病理机制，并建立新的治疗策略用于心脏疾病，如局部缺血和心脏衰竭。 哺乳动物心肌收缩功能已知通过各种离子通道，转运和其他蛋白质被调制。动作电位诱发激活电压依赖性肌膜L型钙通道引出的Ca 2+内流 ，从细胞外空间，并随后到的 Ca 2+ -诱导的 Ca 2+释放（CICR）1，这将触发蜂窝收缩2。钙 -信号起着心脏收缩力和适应方面发挥核心作用的生理或病理压力。儿茶酚胺激活心脏β肾上腺素能受体，从而刺激腺苷酸环化酶（AC）的合成营。被激活，proteiÑ ​​激酶A（PKA）的磷酸化细胞内的不同和膜相关蛋白质如L-型Ca 2+通道 ，磷蛋白和兰尼碱受体导致的钙瞬变和心脏收缩1,3,4修饰。的cAMP通过磷酸二酯酶（PDE）的降解。 G s - 偶联受体比β肾上腺素能受体其它的活化也导致的cAMP蓄积。 心室肌细胞肌条收缩测量的技术已经非常成熟的大型哺乳动物物种5-8。基于基因的可能性靶向小鼠建立的方法来分析鼠心脏生理是重要的。然而，大约在小鼠中分离肌肉制剂的生理特性的现有数据的差异取决于实验条件9-12。 所描述的方法被用来分析左心室乳头肌的预心脏收缩parations 体外 。在没有影响改变心肌收缩力在体内 ，如血压，神经体液刺激和生理或代谢应激进行心肌收缩力的研究。承包肌肉制剂的跳动速率可以严格定义，改变随意。抽搐力能够在特定刺激，如钙浓度，跳动频率或温度的情况下进行分析。此外，这种方法可用于研究不同信号传导途径的组件和通过控制上述实验条件下进行比较的转基因小鼠模型的心脏的性能。

<table><tbody><tr><td>Sodium chloride</td><td>Sigma-Aldrich</td><td>S7653</td><td></td></tr><tr><td>Sodium bicarbonate</td><td>Sigma-Aldrich</td><td>S5761&amp;nbsp;</td><td></td></tr><tr><td>Potassium chloride</td><td>Sigma-Aldrich</td><td>P9333</td><td></td></tr><tr><td>Glucose</td><td>Sigma-Aldrich</td><td>D9434&amp;nbsp;</td><td></td></tr><tr><td>Sodium pyruvate</td><td>Sigma-Aldrich</td><td>P5280&amp;nbsp;</td><td></td></tr><tr><td>Calcium chloride dihydrate</td><td>Sigma-Aldrich</td><td>223506</td><td></td></tr><tr><td>Magnesium sulfate heptahydrate</td><td>Sigma-Aldrich</td><td>230391</td><td></td></tr><tr><td>Potassium phosphate monobasic</td><td>Sigma-Aldrich</td><td>P 5655</td><td></td></tr><tr><td>2,3-Butanedione monoxime</td><td>Sigma-Aldrich</td><td>B0753</td><td></td></tr><tr><td>3-Isobutyl-1-methylxanthine</td><td>Sigma-Aldrich</td><td>I5879</td><td>Hazard statement H 302, solve in DMSO</td></tr><tr><td>Dimethyl sulfoxide (DMSO)</td><td>Sigma-Aldrich</td><td>D2650</td><td></td></tr><tr><td>Isoprenaline hydrochloride</td><td>Sigma-Aldrich</td><td>I5627</td><td>Hazard statement H 315-H319-H335</td></tr><tr><td>Sodium Heparine 250.000 IE/10 ml</td><td>ratiopharm</td><td>PZN 3874685</td><td></td></tr><tr><td>Histamine dihydrochloride</td><td>Sigma-Aldrich</td><td>H7250</td><td>Hazard statement H 315-H 317-H319- H334-H335</td></tr></tbody></table>

contractility measurements on isolated papillary muscles for the investigation of cardiac inotropy in mice

乳头肌从成年小鼠心脏分离，可用于在不同的生理/病理条件下，研究心脏收缩。独立的外部影响，如血管紧张或神经体液状态的收缩特性可以被评估。它描述了单细胞测量孤立心肌细胞之间， 像超声心动图体内研究科学的方法。因此，乳头肌制剂作为一个很好的模型来研究心脏生理/病理生理学和可用于像由药剂的调制或转基因动物模型的探索调查。这里，我们描述分离鼠左前乳头肌以调查在器官浴设置心脏收缩的方法。在对比一个肌肉条准备从心室壁分离，乳头肌可以全盘而不损伤肌肉Tissu酒店制备Ë严重。器官浴设置包括几个温度控制，毒气和电极配备器官浴室。将分离的乳头肌固定在器官浴室和电刺激。诱发抽搐力是使用压力传感器和参数，如抽搐力的振幅和抽搐动力学分析记录。不同的实验方案，可以执行以调查收缩剂如儿茶酚胺或其他药物的碳酸钙和频率相关的收缩以及剂量 - 反应曲线。此外，像急性缺血病理状况可以模拟。

本手稿的孤立鼠的乳头肌收缩制剂测量值的协议被调谐到最佳条件，以实现在生理条件下可再现的实验结果。为了确定最佳的实验条件下，我们进行试点实验，不同的器官浴温度和细胞外钙离子浓度（参见12）。这里描述的协议用的1.5mM的胞外钙浓度和32℃的温度下进行。 基底收缩特性要抽搐力振幅表征基底收缩性质，参数，抽搐率，达峰时间（?...

Watch this Scientific Journal Video about Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice at JoVE.com

Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice

鼠左心室乳头肌可用于研究在体外心脏收缩。本文详细介绍了隔离和实验方案，研究心脏收缩的特点。

对离体乳头肌的心脏收缩力对小鼠的研究收缩尺寸

Papillary muscle isolated from adult mouse hearts can be used to study cardiac contractility during different physiological/pathological conditions. The ...

contractility-measurements-on-isolated-papillary-muscles-for

Research

JoVE Journal

Biology

14.9K 次观看.  Universität Heidelberg. 鼠左心室乳头肌可用于研究在体外心脏收缩。本文详细介绍了隔离和实验方案，研究心脏收缩的特点。 

视频: Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice

In vitro Measurements of Tracheal Constriction Using Mice

Transgenic and knockout mice have been powerful tools for the investigation of the physiology and pathophysiology of airways1,2. In vitro tensometry of isolated tracheal preparations has proven to be a useful assay of airway smooth muscle (ASM) contractile response in genetically modified mice. These in vitro tracheal preparations are relatively simple, provide a robust response, and retain both functional cholinergic nerve endings and muscle responses, even after long incubations.
Tracheal tensometry also provides a functional assay to study a variety of second messenger signaling pathways that affect contraction of smooth muscle. Contraction in trachea is primarily mediated by parasympathetic, cholinergic nerves that release acetylcholine onto ASM (Figure 1). The major ASM acetylcholine receptors are muscarinic M2 and M3 which are Gi/o and Gq coupled receptors, respectively3,4,5. M3 receptors evoke contraction by coupling to Gq to activate phospholipase C, increase IP3 production and IP3-mediated calcium release from the sarcoplasmic reticulum3,6,7. M2/Gi/o signaling is believed to enhance contractions by inhibition of adenylate cyclase leading to a decrease in cAMP levels5,8,9,10. These pathways constitute the so called "pharmaco-contraction coupling" of airway smooth muscle11. In addition, cholinergic signaling through M2 receptors (and modulated by M3 signaling) involves pathways that depolarize the ASM which in turn activate L-type, voltage-dependent calcium channels (Figure 1) and calcium influx (so called "excitation-contraction coupling")4,7. More detailed reviews on signaling pathways controlling airway constriction can be found4,12. The above pathways appear to be conserved between mice and other species. However, mouse tracheas differ from other species in some signaling pathways. Most prominent is their lack of contractile response to histamine and adenosine13,14, both well-known ASM modulators in humans and other species5,15.
Here we present protocols for the isolation of murine tracheal rings and the in vitro measurement of their contractile output. Included are descriptions of the equipment configuration, trachea ring isolation and contractile measurements. Examples are given for evoking contractions indirectly using high potassium stimulation of nerves and directly by depolarization of ASM muscle to activate voltage-dependent calcium influx (1. high K+, Figure 1). In addition, methods are presented for stimulations of nerves alone using electric field stimulation (2. EFS, Figure 1), or for direct stimulation of ASM muscle using exogenous neurotransmitter applied to the bath (3. exogenous ACH, Figure 1). This flexibility and ease of preparation renders the isolated trachea ring model a robust and functional assay for a number of signaling cascades involved in airway smooth muscle contraction.

In vitro Measurements of Tracheal Constriction Using Mice

Transgenic mice have been extremely useful in ascribing physiological function to genes. As such, research in general, and functional studies of airway, in particular, have undergone a remarkable shift toward murine models. Here we provide protocols for in vitro trachea constriction studies to evaluate smooth muscle function in murine airway.

在利用老鼠的气管收缩的体外测量

Transgenic and knockout mice have been powerful tools for the investigation of the physiology and pathophysiology of airways1,2. In vitro tensometry of ...

科研

医学

Cardiac Catheterization in Mice to Measure the Pressure Volume Relationship: Investigating the Bowditch Effect

Animal models that mimic human cardiac disorders have been created to test potential therapeutic strategies. A key component to evaluating these strategies is to examine their effects on heart function. There are several techniques to measure in vivo cardiac mechanics (e.g., echocardiography, pressure/volume relations, etc.). Compared to echocardiography, real-time left ventricular (LV) pressure/volume analysis via catheterization is more precise and insightful in assessing LV function. Additionally, LV pressure/volume analysis provides the ability to instantaneously record changes during manipulations of contractility (e.g., &#946;-adrenergic stimulation) and pathological insults (e.g., ischemia/reperfusion injury). In addition to the maximum (+dP/dt) and minimum (-dP/dt) rate of pressure change in the LV, an accurate assessment of LV function via several load-independent indexes (e.g., end systolic pressure volume relationship and preload recruitable stroke work) can be attained. Heart rate has a significant effect on LV contractility such that an increase in the heart rate is the primary mechanism to increase cardiac output (i.e., Bowditch effect). Thus, when comparing hemodynamics between experimental groups, it is necessary to have similar heart rates. Furthermore, a hallmark of many cardiomyopathy models is a decrease in contractile reserve (i.e., decreased Bowditch effect). Consequently, vital information can be obtained by determining the effects of increasing heart rate on contractility. Our and others data has demonstrated that the neuronal nitric oxide synthase (NOS1) knockout mouse has decreased contractility. Here we describe the procedure of measuring LV pressure/volume with increasing heart rates using the NOS1 knockout mouse model.

This article describes the measurement of murine left ventricular function via pressure/volume analysis at different heart rates.

心导​​管在小鼠测量压力体积的关系:调查的影响鲍迪奇

Animal models that mimic human cardiac disorders have been created to test potential therapeutic strategies. A key component to evaluating these ...

Optical Imaging of Isolated Murine Ventricular Myocytes

The ability to isolate adult cardiac myocytes has permitted researchers to study a variety of cardiac pathologies at the single cell level. While advances in calcium sensitive dyes have permitted the robust optical recording of single cell calcium dynamics, recording of robust transmembrane optical voltage signals has remained difficult. Arguably, this is because of the low single to noise ratio, phototoxicity, and photobleaching of traditional potentiometric dyes. Therefore, single cell voltage measurements have long been confined to the patch clamp technique which while the gold standard, is technically demanding and low throughput. However, with the development of novel potentiometric dyes, large, fast optical responses to changes in voltage can be obtained with little to no phototoxicity and photobleaching. This protocol describes in detail how to isolate adult murine myocytes which can be used for cellular shortening, calcium, and optical voltage measurements. Specifically, the protocol describes how to use a ratiometric calcium dye, a single-excitation calcium dye, and a single excitation voltage dye. This approach can be used to assess the cardiotoxicity and arrhythmogenicity of various chemical agents. While phototoxicity is still an issue at the single cell level, methodology is discussed on how to reduce it.

We present the methodology for the isolation of murine myocytes and how to obtain voltage or calcium traces simultaneously with sarcomere shortening traces using fluorescence photometry with simultaneous digital cell geometry measurements.

分离的月毛心室肌细胞的光学成像

The ability to isolate adult cardiac myocytes has permitted researchers to study a variety of cardiac pathologies at the single cell level. While advances ...

生物工程

Isolation, Culture, and Functional Characterization of Adult Mouse Cardiomyoctyes

The use of primary cardiomyocytes (CMs) in culture has provided a powerful complement to murine models of heart disease in advancing our understanding of heart disease. In particular, the ability to study ion homeostasis, ion channel function, cellular excitability and excitation-contraction coupling and their alterations in diseased conditions and by disease-causing mutations have led to significant insights into cardiac diseases. Furthermore, the lack of an adequate immortalized cell line to mimic adult CMs, and the limitations of neonatal CMs (which lack many of the structural and functional biomechanics characteristic of adult CMs) in culture have hampered our understanding of the complex interplay between signaling pathways, ion channels and contractile properties in the adult heart strengthening the importance of studying adult isolated cardiomyocytes. Here, we present methods for the isolation, culture, manipulation of gene expression by adenoviral-expressed proteins, and subsequent functional analysis of cardiomyocytes from the adult mouse. The use of these techniques will help to develop mechanistic insight into signaling pathways that regulate cellular excitability, Ca2+ dynamics and contractility and provide a much more physiologically relevant characterization of cardiovascular disease.

Here we describe the isolation of adult mouse cardiomyoctyes using a Langendorff perfusion system. The resulting cells are Ca2+-tolerant, electrically quiescent and can be cultured and transfected with adeno- or lentiviruses to manipulate gene expression. Their functionality can also be analyzed using the MMSYS system and patch clamp techniques.

分离，培养和成年小鼠Cardiomyoctyes的功能分析

The use of primary cardiomyocytes (CMs) in culture has provided a powerful complement to murine models of heart disease in advancing our understanding of ...

生物学

Isolation and Physiological Analysis of Mouse Cardiomyocytes

Cardiomyocytes, the workhorse cell of the heart, contain exquisitely organized cytoskeletal and contractile elements that generate the contractile force used to pump blood. Individual cardiomyocytes were first isolated over 40 years ago in order to better study the physiology and structure of heart muscle. Techniques have rapidly improved to include enzymatic digestion via coronary perfusion. More recently, analyzing the contractility and calcium flux of isolated myocytes has provided a vital tool in the cellular and sub-cellular analysis of heart failure. Echocardiography and EKGs provide information about the heart at an organ level only. Cardiomyocyte cell culture systems exist, but cells lack physiologically essential structures such as organized sarcomeres and t-tubules required for myocyte function within the heart. In the protocol presented here, cardiomyocytes are isolated via Langendorff perfusion. The heart is removed from the mouse, mounted via the aorta to a cannula, perfused with digestion enzymes, and cells are introduced to increasing calcium concentrations. Edge and sarcomere detection software is used to analyze contractility, and a calcium binding fluorescent dye is used to visualize calcium transients of electrically paced cardiomyocytes; increasing understanding of the role cellular changes play in heart dysfunction. Traditionally used to test drug effects on cardiomyocytes, we employ this system to compare myocytes from WT mice and mice with a mutation that causes dilated cardiomyopathy. This protocol is unique in its comparison of live cells from mice with known heart function and known genetics. Many experimental conditions are reliably compared, including genetic or environmental manipulation, infection, drug treatment, and more. Beyond physiologic data, isolated cardiomyocytes are easily fixed and stained for cytoskeletal elements. Isolating cardiomyocytes via perfusion is an extremely versatile method, useful in studying cellular changes that accompany or lead to heart failure in a variety of experimental conditions.

Individual cardiomyocytes from wild type and mutant mice can be isolated from the heart in order to study their contractility and calcium transients. This allows characterization of the contribution of cellular dysfunction to heart dysfunction from any cause.

鼠心肌细胞的分离及生理分析

Cardiomyocytes, the workhorse cell of the heart, contain exquisitely organized cytoskeletal and contractile elements that generate the contractile force ...

Dynamic Measurement and Imaging of Capillaries, Arterioles, and Pericytes in Mouse Heart

Coronary arterial tone along with the opening or closing of the capillaries largely determine the blood flow to cardiomyocytes at constant perfusion pressure. However, it is difficult to monitor the dynamic changes of the coronary arterioles and the capillaries in the whole heart, primarily due to its motion and non-stop beating. Here we describe a method that enables monitoring of arterial perfusion rate, pressure and the diameter changes of the arterioles and capillaries in mouse right ventricular papillary muscles. The mouse septal artery is cannulated and perfused at a constant flow or pressure with the other dynamically measured. After perfusion with a fluorescently labeled lectin (e.g., Alexa Fluor-488 or -633 labeled Wheat-Germ Agglutinin, WGA), the arterioles and capillaries (and other vessels) in right ventricle papillary muscle and septum could be readily imaged. The vessel-diameter changes could then be measured in the presence or absence of heart contractions. When genetically encoded fluorescent proteins were expressed, specific features could be monitored. For examples, pericytes were visualized in mouse hearts that expressed NG2-DsRed. This method has provided a useful platform to study the physiological functions of capillary pericytes in heart. It is also suitable for studying the effect of reagents on the blood flow in heart by measuring the vascular/capillary diameter and the arterial luminal pressure simultaneously. This preparation, combined with a state-of-the-art optic imaging system, allows one to study the blood flow and its control at cellular and molecular level in the heart under near-physiological conditions.

Presented here is a protocol to study the coronary microcirculation in living murine heart tissue by ex vivo monitoring of the arterial perfusion pressure and flow that maintains the pressure, as well as vascular tree components including the capillary beds and pericytes, as the septal artery is cannulated and pressurized.

鼠标心脏中毛细血管、动脉和腹膜的动态测量和成像

Coronary arterial tone along with the opening or closing of the capillaries largely determine the blood flow to cardiomyocytes at constant perfusion ...

Revealing Subtle Changes in Cardiac Function using Transthoracic Dobutamine Stress Echocardiography in Mice

Left ventricular (LV) dysfunction paves the final pathway for a multitude of cardiac disorders. With the non-invasive high-frequency transthoracic dobutamine stress echocardiography in humans, a reductionist investigation approach to unmask subtle changes in cardiac function has become possible. Here, we provide a protocol for using this technique in mice to facilitate expanded analysis of LV architecture and function in physiology and pathology enabling the observation of alterations in models of cardiac disease hidden in unstressed hearts. This investigation can be performed in one and the same animal and allows both, basal and pharmacologically stress-induced measurements. We outline detailed criteria for appropriate anesthesia, imaging-based LV analysis, consideration of intra- and interobserver variability, and obtaining positive inotrope response that can be attained in mice after intraperitoneal injection of dobutamine under near physiological conditions. To recapitulate the characteristics of human physiology and disease in small animal models, we highlight critical pitfalls in evaluation, e.g., a pronounced Bowditch effect in mice. To further meet translational objectives, we compare stress-induced effects in humans and mice. When used in translational studies, attention must be paid to physiological differences between mice and human. Experimental rigor dictates that some parameters assessed in patients can only be used with caution due to restrictions in spatial and temporal resolution in mouse models.

Left ventricular dysfunction constitutes the final common pathway for a host of cardiac disorders. We here provide a detailed protocol of transthoracic dobutamine stress echocardiography approach for comprehensive evaluation of the left ventricular function of mouse models of cardiac disease as well as cardiac phenotyping.

Left ventricular (LV) dysfunction paves the final pathway for a multitude of cardiac disorders. With the non-invasive high-frequency transthoracic ...

Analysis of Cardiac Contractile Dysfunction and Ca2+ Transients in Rodent Myocytes

Contractile dysfunction and Ca2+ transients are often analyzed at the cellular level as part of a comprehensive assessment of cardiac-induced injury and/or remodeling. One approach for assessing these functional alterations utilizes unloaded shortening and Ca2+ transient analyses in primary adult cardiac myocytes. For this approach, adult myocytes are isolated by collagenase digestion, made Ca2+ tolerant, and then adhered to laminin-coated coverslips, followed by electrical pacing in serum-free media. The general protocol utilizes adult rat cardiac myocytes but can be readily adjusted for primary myocytes from other species. Functional alterations in myocytes from injured hearts can be compared to sham myocytes and/or to in vitro therapeutic treatments. The methodology includes the essential elements needed for myocyte pacing, along with the cell chamber and platform components. The detailed protocol for this approach incorporates the steps for measuring unloaded shortening by sarcomere length detection and cellular Ca2+ transients measured with the ratiometric indicator Fura-2 AM, as well as for raw data analysis.

Analysis of Cardiac Contractile Dysfunction and Ca2+ Transients in Rodent Myocytes

A set of protocols are presented that describe the measurement of contractile function via sarcomere length detection along with calcium (Ca2+) transient measurement in isolated rat myocytes. The application of this approach for studies in animal models of heart failure is also included.

啮齿动物心肌细胞心脏收缩功能障碍和Ca2+ 瞬变分析

Contractile dysfunction and Ca2+ transients are often analyzed at the cellular level as part of a comprehensive assessment of cardiac-induced injury ...

Measurement of Heart Contractility in Isolated Adult Human Primary Cardiomyocytes

The evaluation of changes in heart contractility is essential during preclinical development for new cardiac- and non-cardiac-targeted compounds. This paper describes a protocol for assessing changes in contractility in adult human primary ventricular cardiomyocytes utilizing the MyoBLAZER, a non-invasive optical method that preserves the normal physiology and pharmacology of the cells. This optical recording method continuously measures contractility transients from multiple cells in parallel, providing both medium-throughput and valuable information for each individual cell in the field of view, enabling the real-time tracking of drug effects. The cardiomyocyte contractions are induced by paced electrical field stimulation, and the acquired bright field images are fed to an image-processing software that measures the sarcomere shortening across multiple cardiomyocytes. This method rapidly generates different endpoints related to the kinetics of contraction and relaxation phases, and the resulting data can then be interpreted in relation to different concentrations of a test article. This method is also employed in the late stages of preclinical development to perform follow-up mechanistic studies to support ongoing clinical studies. Thus, the adult human primary cardiomyocyte-based model combined with the optical system for continuous contractility monitoring has the potential to contribute to a new era of in vitro cardiac data translatability in preclinical medical therapy development.

This protocol describes how to measure contractility in adult human primary cardiomyocytes from donor hearts with the MyoBLAZER system, a reliable platform for assessing drug-induced changes in contractility during preclinical development.

分离的成人原代心肌细胞心脏收缩力的测量

The evaluation of changes in heart contractility is essential during preclinical development for new cardiac- and non-cardiac-targeted compounds. This ...

Mechanical Control of Relaxation Using Intact Cardiac Trabeculae

Diastolic dysfunction is a common phenotype across cardiovascular disease presentations. In addition to elevated cardiac stiffness (elevated left ventricular end-diastolic pressure), impaired cardiac relaxation is a key diagnostic indicator of diastolic dysfunction. While relaxation requires the removal of cytosolic calcium and deactivation of sarcomeric thin filaments, targeting such mechanisms has yet to provide effective treatments. Mechanical mechanisms, such as blood pressure (i.e., afterload), have been theorized to modify relaxation. Recently, we showed that modifying the strain rate of a stretch, not afterload, was both necessary and sufficient to modify the subsequent relaxation rate of myocardial tissue. The strain rate dependence of relaxation, called the mechanical control of relaxation (MCR), can be assessed using intact cardiac trabeculae. This protocol describes the preparation of a small animal model, experimental system and chamber, isolation of the heart and subsequent isolation of a trabecula, preparation of the experimental chamber, and experimental and analysis protocols. Evidence for lengthening strains in the intact heart suggests that MCR might provide new arenas for better characterization of pharmacological treatments, along with a method to assess myofilament kinetics in intact muscles. Therefore, studying the MCR may elucidate a path to novel approaches and new frontiers in the treatment of heart failure.

Rapid myocardial and cardiac relaxation is essential for normal physiology. Mechanical relaxation mechanisms are now known to be dependent on strain rate. This protocol provides an overview of the acquisition and analysis of experiments to further study the mechanical control of relaxation.

对离体乳头肌的心脏收缩力对小鼠的研究收缩尺寸

摘要

探索更多视频

此视频中的章节

在利用老鼠的气管收缩的体外测量

心导管在小鼠测量压力体积的关系:调查的影响鲍迪奇

分离的月毛心室肌细胞的光学成像

分离，培养和成年小鼠Cardiomyoctyes的功能分析

鼠心肌细胞的分离及生理分析

鼠标心脏中毛细血管、动脉和腹膜的动态测量和成像

Revealing Subtle Changes in Cardiac Function using Transthoracic Dobutamine Stress Echocardiography in Mice

啮齿动物心肌细胞心脏收缩功能障碍和^Ca2+ 瞬变分析

分离的成人原代心肌细胞心脏收缩力的测量

使用完整的心脏小梁机械控制松弛

对离体乳头肌的心脏收缩力对小鼠的研究收缩尺寸

摘要

探索更多视频

此视频中的章节

在利用老鼠的气管收缩的体外测量

心导​​管在小鼠测量压力体积的关系:调查的影响鲍迪奇

分离的月毛心室肌细胞的光学成像

分离，培养和成年小鼠Cardiomyoctyes的功能分析

鼠心肌细胞的分离及生理分析

鼠标心脏中毛细血管、动脉和腹膜的动态测量和成像

Revealing Subtle Changes in Cardiac Function using Transthoracic Dobutamine Stress Echocardiography in Mice

啮齿动物心肌细胞心脏收缩功能障碍和Ca2+ 瞬变分析

分离的成人原代心肌细胞心脏收缩力的测量

使用完整的心脏小梁机械控制松弛

心导管在小鼠测量压力体积的关系:调查的影响鲍迪奇

啮齿动物心肌细胞心脏收缩功能障碍和^Ca2+ 瞬变分析