Çalıştaylar ve Nörofizyoloji Enstitüsünün hayvan tesisi tarafından sağlanan desteği onaylıyoruz. Bu çalışma Walter und Marga Boll Stiftung, Köln Fortune ve Deutsche Stiftung für Herzforschung tarafından desteklendi.

Hayvanların taşınması, yerel hayvan refahı komitesinin ve Avrupa Parlamentosu&#39;nun 2010/63 / AB sayılı Direktifinin kurallarına uymalıdır. 1. Çözümleri Hazırlama <ol><li> Tyrode&#39;nin solüsyonunu Ca 2+ olmadan (mM&#39;de kompozisyon) hazırlayın: NaCI 136, KCl 5.4, NaH2PO4.33, MgCl2, glikoz 10, HEPES 5, 2,3-butandion monoksim (BDM) 30. pH&#39;ı 7.4&#39;e ayarlayın NaOH ile 4 ° C&#39;de. </li><li> Tyrode çözeltisini Ca 2+ (bileşim mM cinsinden) ile hazırlayın: NaCl 136, KCl 5.4, NaH2PO4.33, MgCl2, glikoz 10, HEPES 5, BDM 30, CaCl 2 0.9. 4 ° C&#39;de NaOH ile pH&#39;ı 7.4&#39;e ayarlayın. </li><li> % 4 düşük eriyikli agaroz hazırlayın: Ca 2+ içermeyen 0.6 mL düşük eriyikli agaroz 15 mL Tyrode çözeltisine koyun. Karışımı, bir mikrodalga fırında iki kez 750 W&#39;de 10-15 saniye boyunca, agaroz çözünene kadar ısıtın. Çözeltiyi 37 ° C&#39;de sabit bir sıcaklıkta tutun.# 176; C ve sürekli karıştırın. </li><li> Dulbecco&#39;nun Değiştirilmiş Kartal Ortamını (DMEM) 37 ° C&#39;de serum olmadan carbogen (% 5 CO 2 ,% 95 O 2 ) ile kabarcıklarken muhafaza edin. </li></ol> 2. Microtome&#39;u hazırlayın <ol><li> Mikrogramı açın. </li><li> Dış mikrotom hücresini buzla doldurun. </li><li> İç mikrotom bölmesini, Ca 2+ içermeyen soğuk Tyrode çözeltisi ile doldurun ve çözeltiyi% 100 O 2 ile sürekli olarak oksijene koyun. </li><li> Mikro topuzun bıçak tutucusuna bir çelik bıçak takın. </li></ol> 3. Fare Kalp İzolasyonu <ol><li> 2,500 U Heparin&#39;i subkütan enjekte edin. 15 dakika bekleyin. </li><li> Hayvanı servikal dislokasyon ile kurban edin. </li><li> Sternotomi ile göğsünü açın. </li><li> Küçük makas ve bir forseps # 5 kullanarak perikardı dikkatle inceleyin. </li><li> Artan aortaya bir kanül yerleştirin ve koroner arterleri buz gibi soğuk Tyrode&#39;lerle in situ olarak perfüze edinKalan kan alınana kadar Ca 2+ içermeyen bir solüsyon. </li><li> Kalbi bir forseps ve makasla hafifçe kesip kalbi buz soğukluğunda transfer edin Tyrode&#39;nin çözümü Ca 2+ olmadan sürdü. </li><li> Atriyumu ventriküllerden bir neşter veya makasla ayırın. </li></ol> 4. Ventriküllerin% 4 Düşük Erime Agaroza Katılması <ol><li> Ventrikülleri, tepe kısmı yukarı bakacak şekilde agaroz kalıbına yerleştirin ( Şekil 1 ). Pimi sol ventriküler bölmedeki kalıbın ortasına yerleştirin. </li><li> Kalıbı, kalp tamamen kaplanıncaya kadar 37 ° C&#39;de% 4 düşük eriyikli agaroz ile doldurun. </li><li> Agarozun daha hızlı sertleşmesi için kalıbı buz üzerinde bırakın, dokunun yüzmesini önleyin. </li><li> Ventrikül içeren agaroz bloğu bir bistül ile kalıptan çıkarın. </li><li> Bloğu ters çevirin ve ventriküler odaları ve agaroz bloğun arkasındaki boşluğu doldurun;20 G&#39;lik bir iğneli bir şırınga kullanarak% 4 düşük eriyikli agaroz ile moltun iğnesi bıraktı. </li><li> Blok düz bir alt ve kalp apeksinin dik pozisyonunu elde etmek için agaroz bloğu bir neşter ile kesin. </li></ol> 5. Ventriküler Doku Dilimleme <ol><li> Bir damla cyanoacrylate tutkalı ile mikrotomun numune tutucusundaki bloğu sabitleyin. Kardiyak üstü yukarı bakacak şekilde tasarlayın. </li><li> Örnek tutucuyu, Ca 2+ içermeyen buz gibi soğuk Tyrode ile dolu mikrotomun iç numune bölmesine yerleştirin. Tyrode&#39;nin çözeltisiyle agaroz bloğu tamamen örtün. </li><li> Diğer uygulamalara (keskin elektrot kayıtları 150-200 μm için) bağlı olarak 150-400 μm kalınlığında kısa eksen dilimleri hazırlayın, bıçağın titreşim frekansı 60-70 Hz&#39;de tutun ve bıçağı mümkün olduğunca yavaş ileri hareket ettirin . </li><li> Kalan agarozu dilimlerden dikkatlice çıkarmak için ince bir fırça kullanın. </li><li> Nazikçe gönderR dilimleri,% 0.9 O 2 ile havalandırılan 0.9 mM Ca 2 + ile Tyrode solüsyonuna bir Pasteur pipet ile dilimleme prosedüründen kurtulmak için buz üzerinde en az 30 dakika saklayın. </li><li> Ardından, daha fazla kullanılmadan önce BDM&#39;yi yıkamak için 30 dakika süreyle DMEM&#39;de 37 ° C&#39;de dilimler bırakın, karbogenle havalandırın. </li></ol> 6. Keskin Elektrot Kurulumunun Hazırlanması <ol><li> Ön ısıtma için, kayıtların başlamasından 30 dakika önce tüm elektrikli cihazları açın. </li><li> Ters çevrilmiş mikroskopta yer alan ısıtma plakasına 3 cm&#39;lik hücre kültürü kabı koyun. </li><li> Özel yapım halka elektrotunu ( Şekil 2 ) çanağa yerleştirin ve ön amplifikatörün ve stimülasyon elektrodunun topraklama kablolarını bağlayın. </li><li> Perfüzyon sisteminin esnek borularını çanağa bağlayın. </li><li> Perfüzyon sisteminin rezervuarını karbogen ile havalandırılmış DMEM ile doldurun. </li><li> Perfüzyon pompasını açın ve perfüzyon rafini ayarlayın2-3 mL / dk&#39;ya kadar ısıtıldı. </li><li> Akış ısıtıcısını ve ısıtma plakasını düzenleyerek çanak içindeki DMEM sıcaklığını 37 ° C&#39;ye ayarlayın. </li></ol> 7. İşlem Potansiyel Kayıtları <ol><li> DMEM dolu tabağa bir ventriküler dilim yerleştirin. </li><li> Ters çevrilmiş mikroskop ile yapının yapısal bütünlüğünü ve yaşayabilirliğini kontrol edin (kontraktil fonksiyona dayanmaktadır). </li><li> Bir kayıt cam elektrodu 3 M KCL ile doldurun. </li><li> Bir uyarılma elektrotunu DMEM ile doldurun. </li><li> Kayıt elektrodunu ve stimülasyon elektrodunu elektrot tutucularının üzerine yerleştirin. </li><li> Uyarı elektrodunu dilim üzerine dikkatle yerleştirin ve elektrik stimülatörünü açın. 1-2 Hz&#39;lik bir stimülasyon frekansı ile başlayın. </li><li> Kayıt elektrodunu mikromanipülatör ile istenen kayıt pozisyonunun üzerine getirin. </li><li> İpucu dokuya dokunana kadar kayıt elektrodunu yavaşça indirin. </li><li> Şebekeden kısa dikdörtgen elektrik darbesi uygulayın.Kayıt elektrotu hücre zarı içine nüfuz eder. </li><li> Kayıt elektrodunu kararlı bir sinyal gelene kadar dikkatlice yeniden konumlandırın. </li><li> Aksiyon potansiyellerinin kaydını başlatın. </li></ol>

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Yazarların beyan edecek hiçbir şeyi yok.

Ventriküler dilimler, korunmuş bir in vivo doku yapısı ve ölçme teknolojisinin kalbin tüm bölgelerine doğrudan erişimi ile elektrofizyolojik, farmakolojik ve mekanik çalışmalara olanak tanır. Fizyolojik aksiyon potansiyel özellikleri embriyonik, neonatal ve erişkin dilimlerde gösterilmiştir 9,10,11. Dilimleme işlemi ile doğrudan hasar gören yüzey tabakaları haricindeki dilimlerin canlılığı, canlılık boyaması ile teyit edilmiştir 9 . Burada açıklandığı ...

Yamamot ve Mcllwain 1966&#39;da beyin dilimlerinin elektriksel aktivitesinin in vitro muhafaza edildiğini gösterdiklerinden beri temel bilimde ince doku dilimleri sıklıkla kullanılmıştır. O zamandan beri, beyin 2 , karaciğer 3 , akciğer 4 ve miyokard dokusu 5 , 6 , 7 dilimleri üzerinde elektrofizyolojik ve farmakolojik çalışmalar yürütülmüştür. Yenidoğan sıçan kalplerindeki ventriküler dilimlerde ilk yama-kelepçe kayıtları 1990&#39;da 8&#39;de tanımlanmıştır, ancak bu teknik bir süre unutulmaya uğradı. Birkaç yıl sonra grubumuz, fare embriyonik 9 , neonatal 10 ve erişkin 11 kalp dilimlerini hazırlamak için yeni bir yöntem geliştirdi. Bu canlı doku dilimleri akut deneyler için kullanılabilir (erişkin dilimS birkaç saat ekilebilir) veya kısa vadeli kültür deneyleri (embriyonik ve yenidoğan dilimleri birkaç gün boyunca yetiştirilebilir). Kesitler elektrofizyolojik özelliklere benzer şekilde in vivo olarak gösterirler ve keskin elektrot aksiyon potansiyeli ve mikro elektrot dizisi kayıtları ile değerlendirildiğinde homojen bir uyarılma yayılır 11 . &quot;İki boyutlu&quot; morfolojilerinden dolayı kayıt elektrotlarının ventrikülün tüm bölgelerine doğrudan erişmelerine izin veriyorlar, bu da elektrofizyolojik araştırmalar için ilginç bir araç haline getiriyor ve Langendorff tarafından perfüze edilmiş kalpler ile karşılaştırıldığında yeni deneysel seçenekler getiriyor. Dilimlerin verapamil (L-tipi Ca2 + -kanal bloke edicisi), lidokain (Na + -kanal bloke edicisi), 4-aminopiridin (seçici olmayan voltaja bağımlı K + -kanal bloke edici) ve linopirdin (KCNQ K) gibi ilaçların iyon tutucu etkisi + -kanal bloke edici) 9 , 11 </suP&gt; ayrışmış kardiyomiyositlerde bilinen etkilere karşılık gelmektedir. İzometrik kuvvet ölçümleri pozitif bir kuvvet frekansı ilişkisi ortaya koydu ve güçlü kasılma fonksiyonu önerdi10. Bu bulgular, sıçanın ventriküler dilimlerinin fizyolojik ve farmakolojik çalışmalar için in vitro bir doku modeli olarak uygun olduğunu göstermiştir. Ayrıca, kesici elektrot kayıtları ile birlikte alıcı kalplerin ventriküler dilimleri, transplanted fetal 12 , 13 , 14 ve kök hücre kaynaklı 15 kardiyomiyositlerin olgunlaşması yanı sıra elektriksel ve mekanik entegrasyonu karakterize etmek için çok yararlı bir araç olduğu kanıtlanmıştır. Özetle, ventriküler dilimler değerli ve iyi kurulmuş bir çok hücreli doku modeli olup ayrışmış kardiyomiyositleri ve Langendorff perfüze edilen kalpler için tamamlayıcı olarak düşünülmelidir(Dissociated hücrelere karşıt olarak) bir in vivo benzeri doku yapısı sağlamanın yanı sıra keskin elektrot kayıtları gibi (kalp preparatlarının aksine) kalbin tüm bölgelerine doğrudan erişim sağlayan en büyük avantajı olan kardiyovasküler araştırmalardır.

<table><tbody><tr><td>Leica VT 1000s</td><td>Leica Microsystems, Wetzlar, Germany</td><td></td><td>Microtome with vibrating blade.</td></tr><tr><td>Stainless Steel Blades</td><td>Campden Instruments, Loughborough, England</td><td>7550-1-SS</td><td></td></tr><tr><td>Pasteur pipettes</td><td>Sigma-Aldrich, St. Louise, USA</td><td>Z627992</td><td></td></tr><tr><td>Fine brush, &lt;em&gt;e.g.&lt;/em&gt; size 6 (4/32&quot;)</td><td>VWR, International, Radnor, USA</td><td>149-2125</td><td></td></tr><tr><td>Preparation table</td><td></td><td></td><td>self made</td></tr><tr><td>Molt for embedding ventricles in agarose</td><td></td><td></td><td>self made</td></tr><tr><td>1 mL Syringe</td><td>Becton, Dickinson; Franklin Lakes, USA</td><td>300013</td><td></td></tr><tr><td>27 G x 3/4`` Needles</td><td>Braun, Melsungen, Germany</td><td>4657705</td><td></td></tr><tr><td>20 G 11/2`` Needles</td><td>4657519</td><td></td><td></td></tr><tr><td>Small scissor</td><td>WPI, Sarasota, USA</td><td>501263</td><td></td></tr><tr><td>Tweezers #5, 0.1 x 0.06 mm tip</td><td>WPI, Sarasota, USA</td><td>500342</td><td></td></tr><tr><td>Oxygen gas (medical grade O&lt;sub&gt;2&lt;/sub&gt;)</td><td>Linde, Munich, Germany</td><td></td><td></td></tr><tr><td>Carbogen gas (95 % O&lt;sub&gt;2&lt;/sub&gt;, 5 % CO&lt;sub&gt;2&lt;/sub&gt;)</td><td>Linde, Munich, Germany</td><td></td><td></td></tr><tr><td>NaCl</td><td>Sigma-Aldrich, St. Louise, USA</td><td>7647-14-5</td><td></td></tr><tr><td>KCl</td><td>Sigma-Aldrich, St. Louise, USA</td><td>746436</td><td></td></tr><tr><td>CaCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma-Aldrich, St. Louise, USA</td><td>746495</td><td></td></tr><tr><td>KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma-Aldrich, St. Louise, USA</td><td>NIST200B</td><td></td></tr><tr><td>HEPES</td><td>Sigma-Aldrich, St. Louise, USA</td><td>51558</td><td></td></tr><tr><td>NaHCO&lt;sub&gt;3&lt;/sub&gt;</td><td>Sigma-Aldrich, St. Louise, USA</td><td>S5761</td><td></td></tr><tr><td>D(+)-Glucose</td><td>Sigma-Aldrich, St. Louise, USA</td><td>G8270</td><td></td></tr><tr><td>MgSO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma-Aldrich, St. Louise, USA</td><td>M7506</td><td></td></tr><tr><td>NaOH</td><td>Sigma-Aldrich, St. Louise, USA</td><td>S8045</td><td></td></tr><tr><td>Cyanoacrylate glue</td><td>Henkel, D&amp;uuml;sseldorf, Germany</td><td></td><td></td></tr><tr><td>Low-melt Agarose</td><td>Roth, Karlsruhe, Germany</td><td>6351.2</td><td></td></tr><tr><td>Heparin-sodium-25000 I.E./5 mL</td><td>Ratiopharm, Ulm, Germany</td><td></td><td></td></tr><tr><td>Dulbecco&#039;s Modified Eagle Medium (DMEM), high glucose, GlutaMAX</td><td>ThermoScientific, Waltham, USA</td><td>10566016</td><td></td></tr><tr><td>SEC-10LX Amplifier</td><td>npi electronic GmbH, Tamm, Germany</td><td>SEC-10LX</td><td></td></tr><tr><td>EPC 9</td><td>HEKA Elektronik GmbH, Lambrecht, Germany</td><td></td><td></td></tr><tr><td>Zeiss Axiovert 200</td><td>Zeiss, Oberkochen, Germany</td><td></td><td></td></tr><tr><td>Low magnification Micromanipulator</td><td>Narashige, Tokyo, Japan</td><td>Nm-3</td><td></td></tr><tr><td>High magnification, three-axis micromanipulator</td><td>Narashige, Tokyo, Japan</td><td>MHW-3</td><td></td></tr><tr><td>Peristaltic perfusion pump</td><td>Multi Channel Systems, Reutlingen, Germany</td><td>PPS2</td><td></td></tr><tr><td>2-channel temperature controller</td><td>Multi Channel Systems, Reutlingen, Germany</td><td>TCO02</td><td></td></tr><tr><td>Square pulse stimulator</td><td>Natus Europe GmbH, Planegg, Germany</td><td>Grass SD9</td><td></td></tr><tr><td>Glass capillaries</td><td>WPI, Sarasota, USA</td><td>1B150F-1</td><td></td></tr></tbody></table>

murine short axis ventricular heart slices for electrophysiological studies

Fare kardiyomiyositleri , in vitro kardiyak fizyoloji çalışmaları ve yeni tedavi stratejileri için yoğun şekilde kullanılmaktadır. Bununla birlikte, ayrışmış kardiyomiyositlerin çok hücreli preparatları, kalbin hem mekanik hem de elektrofizyolojik özelliklerini etkileyen kardiyomiyositlerin, miyositlerin ve hücre dışı matrisin in vivo yapısının kompleksini temsil etmez. Burada, korunmuş in vivo doku yapısı ile yetişkin fare kalplerindeki canlı ventriküler dilimleri hazırlamak için bir teknik ve elektrofizyolojik kayıtlara uygunluğunu göstermek için bir teknik açıklanmaktadır. Kalbin eksizyonundan sonra, ventriküller atriyumdan ayrılır, 2,3-butandion monoksim içeren Ca2 + içermeyen çözelti ile perfüzyonlanır ve% 4&#39;lük düşük eriyikli agaroz blok içine gömülür. Blok titreşen bir bıçakla mikrotom üzerine yerleştirilir ve 150-400 μm kalınlığa sahip doku dilimleri titreşimi serbest bırakarak hazırlanır60 Hz&#39;de bıçak sıklığı ve bıçağı mümkün olduğunca yavaş ileri hareket ettirerek. Dilimlerin kalınlığı diğer uygulamalara bağlıdır. Dilimler buz soğukluğundaki Tyrode çözeltisinde 0.9 mM Ca 2+ ve 2,3-butandion monoksim (BDM) ile 30 dakika süreyle saklanır. Ardından, BDM&#39;yi yıkamak için dilimler 37 ° C DMEM&#39;ye 30 dakika boyunca aktarılır. Dilimler, kesici elektrodlar veya mikro elektrot dizileri ile elektrofizyolojik çalışmalar için, kontraktil fonksiyonu analiz etmek için güç ölçümleri için veya nakledilen kök hücre kaynaklı kardiyomiyositlerin ve konakçı doku arasındaki etkileşimi araştırmak için kullanılabilir. Keskin elektrot kayıtları için, bir dilim, ters çevrilmiş mikroskopun ısıtma plakasındaki 3 cm&#39;lik hücre kültürü çanağına yerleştirilir. Dilim bir tek kutuplu elektrot ile uyarılır ve dilim içindeki kardiyomiyositlerin hücre içi eylem potansiyelleri keskin bir cam elektrot ile kaydedilir.

Miyokard enfarktüsü kardiyomiyositlerin neredeyse geri döndürülemez bir kaybına yol açar. Eksojen kardiyak rejenerasyon için kök hücre kaynaklı kardiyomiyositleri kullanarak hücre replasman tedavisi umut verici bir tedavi yaklaşımıdır. Transplante hücrelerin elektriksel entegrasyonu ve olgunlaşması, hücre replasman tedavisinin güvenilirliği ve etkinliği için çok önemlidir. Entegrasyon ve olgunlaşmay?...

Watch this Scientific Journal Video about Murine Short Axis Ventricular Heart Slices for Electrophysiological Studies at JoVE.com

Murine Short Axis Ventricular Heart Slices for Electrophysiological Studies

Burada, yetişkin farelerden canlı ventriküler dilimlerin hazırlanmasını ve keskin elektrodun hareket potansiyel kayıtları için kullanımlarını açıklıyoruz. Bu çok hücreli müstahzarlar , in vitro olarak elektrofizyolojik ve farmakolojik çalışmalar için değerli bir model oluşturan, korunmuş bir in vivo doku yapısı sağlar.

Elektrofizyolojik Çalışmalar İçin Murin Kısa Eksenli Ventriküler Kalp Dilimleri

Murine cardiomyocytes have been extensively used for in vitro studies of cardiac physiology and new therapeutic strategies. However, multicellular ...

murine-short-axis-ventricular-heart-slices-for-electrophysiological

Research

JoVE Journal

Medicine

7.3K Görüntüleme.  University of Cologne.  Burada, yetişkin farelerden canlı ventriküler dilimlerin hazırlanmasını ve keskin elektrodun hareket potansiyel kayıtları için kullanımlarını açıklıyoruz. Bu çok hücreli müstahzarlar , in vitro olarak elektrofizyolojik ve farmakolojik çalışmalar için değerli bir model oluşturan, korunmuş bir in vivo doku yapısı sağlar. 

Video: Murine Short Axis Ventricular Heart Slices for Electrophysiological Studies

Optical Mapping of Action Potentials and Calcium Transients in the Mouse Heart

The mouse heart is a popular model for cardiovascular studies due to the existence of low cost technology for genetic engineering in this species. Cardiovascular physiological phenotyping of the mouse heart can be easily done using fluorescence imaging employing various probes for transmembrane potential (Vm), calcium transients (CaT), and other parameters. Excitation-contraction coupling is characterized by action potential and intracellular calcium dynamics; therefore, it is critically important to map both Vm and CaT simultaneously from the same location on the heart1-4. Simultaneous optical mapping from Langendorff perfused mouse hearts has the potential to elucidate mechanisms underlying heart failure, arrhythmias, metabolic disease, and other heart diseases. Visualization of activation, conduction velocity, action potential duration, and other parameters at a myriad of sites cannot be achieved from cellular level investigation but is well solved by optical mapping1,5,6. In this paper we present the instrumentation setup and experimental conditions for simultaneous optical mapping of Vm and CaT in mouse hearts with high spatio-temporal resolution using state-of-the-art CMOS imaging technology. Consistent optical recordings obtained with this method illustrate that simultaneous optical mapping of Langendorff perfused mouse hearts is both feasible and reliable.

This paper details the dissection procedure, instrumental setup, and experimental conditions during optical mapping of transmembrane potential (Vm) and intracellular calcium transient (CaT) in intact isolated Langendorff perfused mouse hearts.

Fare Kalp Aksiyon Potansiyelleri ve Kalsiyum Geçici Optik Haritalama

The mouse heart is a popular model for cardiovascular studies due to the existence of low cost technology for genetic engineering in this species. ...

Biyomühendislik

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.

İzole Murine Ventriküler Miyositlerin Optik Görüntülemesi

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

Preclinical Cardiac Electrophysiology Assessment by Dual Voltage and Calcium Optical Mapping of Human Organotypic Cardiac Slices

Human cardiac slice preparations have recently been developed as a platform for human physiology studies and therapy testing to bridge the gap between animal and clinical trials. Numerous animal and cell models have been used to examine the effects of drugs, yet these responses often differ in humans. Human cardiac slices offer an advantage for drug testing in that they are directly derived from viable human hearts. In addition to having preserved multicellular structures, cell-cell coupling, and extracellular matrix environments, human cardiac tissue slices can be used to directly test the effect of innumerable drugs on adult human cardiac physiology. What distinguishes this model from other heart preparations, such as whole hearts or wedges, is that slices can be subjected to longer-term culture. As such, cardiac slices allow for studying the acute as well as chronic effects of drugs. Furthermore, the ability to collect several hundred to a thousand slices from a single heart makes this a high-throughput model to test several drugs at varying concentrations and combinations with other drugs at the same time. Slices can be prepared from any given region of the heart. In this protocol, we describe the preparation of left ventricular slices by isolating tissue cubes from the left ventricular free wall and sectioning them into slices using a high precision vibrating microtome. These slices can then either be subjected to acute experiments to measure baseline cardiac electrophysiological function or cultured for chronic drug studies. This protocol also describes dual optical mapping of cardiac slices for simultaneous recordings of transmembrane potentials and intracellular calcium dynamics to determine the effects of the drugs being investigated.

This protocol describes the procedure for sectioning and culturing human cardiac slices for preclinical drug testing and details the use of optical mapping for recording transmembrane voltage and intracellular calcium signals simultaneously from these slices.

İnsan Organotipik Kardiyak Dilimlerinin Çift Voltaj ve Kalsiyum Optik Haritalaması ile Preklinik Kardiyak Elektrofizyoloji Değerlendirmesi

Human cardiac slice preparations have recently been developed as a platform for human physiology studies and therapy testing to bridge the gap between ...

Electrophysiological Assessment of Murine Atria with High-Resolution Optical Mapping

Recent genome-wide association studies targeting atrial fibrillation (AF) have indicated a strong association between the genotype and electrophysiological phenotype in the atria. That encourages us to utilize a genetically-engineered mouse model to elucidate the mechanism of AF. However, it is difficult to evaluate the electrophysiological properties in murine atria due to their small size. This protocol describes the electrophysiological evaluation of atria using an optical mapping system with a high temporal and spatial resolution in Langendorff perfused murine hearts. The optical mapping system is assembled with dual high-speed complementary metal oxide semiconductor cameras and high magnification objective lenses, to detect the fluorescence of a voltage-sensitive dye and Ca2+ indicator. To focus on the assessment of murine atria, optical mapping is performed with an area of 2 mm &#215; 2 mm or 10 mm x 10 mm, with a 100 &#215; 100 resolution (20 &#181;m/pixel or 100 &#181;m/pixel) and sampling rate of up to 10 kHz (0.1 ms) at maximum. A 1-French size quadripolar electrode pacing catheter is placed into the right atrium through the superior vena cava avoiding any mechanical damage to the atrium, and pacing stimulation is delivered through the catheter. An electrophysiological study is performed with programmed stimulation including constant pacing, burst pacing, and up to triple extrastimuli pacing. Under a spontaneous or pacing rhythm, the optical mapping recorded the action potential duration, activation map, conduction velocity, and Ca2+ transient individually in the right and left atria. In addition, the programmed stimulation also determines the inducibility of atrial tachyarrhythmias. Precise activation mapping is performed to identify the propagation of the excitation in the atrium during an induced atrial tachyarrhythmia. Optical mapping with a specialized setting enables a thorough electrophysiological evaluation of the atrium in murine pathological models.

This protocol describes the electrophysiological evaluation of murine atria utilizing an optical mapping system with a high temporal and spatial resolution, including dual recordings of the membrane voltage and Ca2+ transient under programmed stimulation through a specialized electrode catheter.

Yüksek çözünürlüklü optik eşleştirmenin fare Atria Elektrofizyolojik değerlendirme

Recent genome-wide association studies targeting atrial fibrillation (AF) have indicated a strong association between the genotype and ...

Tıp

Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes

KCNE genes encode for a small family of Kv channel ancillary subunits that form heteromeric complexes with Kv channel alpha subunits to modify their functional properties. Mutations in KCNE genes have been found in patients with cardiac arrhythmias such as the long QT syndrome and/or atrial fibrillation. However, the precise molecular pathophysiology that leads to these diseases remains elusive. In previous studies the electrophysiological properties of the disease causing mutations in these genes have mostly been studied in heterologous expression systems and we cannot be sure if the reported effects can directly be translated into native cardiomyocytes. In our laboratory we therefore use a different approach. We directly study the effects of KCNE gene deletion in isolated cardiomyocytes from knockout mice by cellular electrophysiology - a unique technique that we describe in this issue of the Journal of Visualized Experiments. The hearts from genetically engineered KCNE mice are rapidly excised and mounted onto a Langendorff apparatus by aortic cannulation. Free Ca2+ in the myocardium is bound by EGTA, and dissociation of cardiac myocytes is then achieved by retrograde perfusion of the coronary arteries with a specialized low Ca2+ buffer containing collagenase. Atria, free right ventricular wall and the left ventricle can then be separated by microsurgical techniques. Calcium is then slowly added back to isolated cardiomyocytes in a multiple step comprising washing procedure. Atrial and ventricular cardiomyocytes of healthy appearance with no spontaneous contractions are then immediately subjected to electrophysiological analyses by patch clamp technique or other biochemical analyses within the first 6 hours following isolation.

Kv channel dysfunction is associated with cardiac arrhythmias. In order to study the molecular mechanisms that lead to such arrhythmias we utilize a systematic protocol for isolation of atrial and ventricular cardiomyocytes from Kv channel ancillary subunit knockout mice. Isolated cardiomyocytes can then immediately be used for cellular electrophysiological studies, biochemical or immunofluorescence (IF) assays.

Mürin Atriyal ve Ventriküler kardiyomiyositlerde izolasyonu ve Kv Kanal Kayıtları

KCNE genes encode for a small family of Kv channel ancillary subunits that form heteromeric complexes with Kv channel alpha subunits to modify their ...

Biyoloji

Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts

Small animal models are most commonly used in cardiovascular research due to the availability of genetically modified species and lower cost compared to larger animals. Yet, larger mammals are better suited for translational research questions related to normal cardiac physiology, pathophysiology, and preclinical testing of therapeutic agents. To overcome the technical barriers associated with employing a larger animal model in cardiac research, we describe an approach to measure physiological parameters in an isolated, Langendorff-perfused piglet heart. This approach combines two powerful experimental tools to evaluate the state of the heart: electrophysiology (EP) study and simultaneous optical mapping of transmembrane voltage and intracellular calcium using parameter sensitive dyes (RH237, Rhod2-AM). The described methodologies are well suited for translational studies investigating the cardiac conduction system, alterations in action potential morphology, calcium handling, excitation-contraction coupling and the incidence of cardiac alternans or arrhythmias.

The objective of this study was to establish a method for investigating cardiac dynamics using a translational animal model. The described experimental approach incorporates dual-emission optocardiography in conjunction with an electrophysiological study to assess electrical activity in an isolated, intact porcine heart model.

Ex Vivo Langendorff perfüzyonlu Kalplerin Optokardiyografi ve Elektrofizyoloji Çalışmaları

Small animal models are most commonly used in cardiovascular research due to the availability of genetically modified species and lower cost compared to ...

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice

The sinoatrial node (SAN), located in the right atrium, contains the pacemaker cells of the heart, and dysfunction of this region can cause tachycardia or bradycardia. Reliable identification of cardiac pacemaking defects requires the measurement of intrinsic heart rates by largely preventing the influence of the autonomic nervous system, which can mask rate deficits. Traditional methods to analyze intrinsic cardiac pacemaker function include drug-induced autonomic blockade to measure in vivo heart rates, isolated heart recordings to measure intrinsic heart rates, and sinoatrial strip or single-cell patch-clamp recordings of sinoatrial pacemaker cells to measure spontaneous action potential firing rates. However, these more traditional techniques can be technically challenging and difficult to perform. Here, we present a new methodology to measure intrinsic cardiac firing rate by performing microelectrode array (MEA) recordings of whole-mount sinoatrial node preparations from mice. MEAs are composed of multiple microelectrodes arranged in a grid-like pattern for recording in vitro extracellular field potentials. The method described herein has the combined advantage of being relatively faster, simpler, and more precise than previous approaches for recording intrinsic heart rates, while also allowing easy pharmacological interrogation.

This protocol aims to describe a new methodology to measure intrinsic cardiac firing rate using microelectrode array recording of the whole sinoatrial node tissue to identify pacemaking defects in mice. Pharmacological agents can also be introduced in this method to study their effects on intrinsic pacemaking.

Farelerde İçSel Kardiyak Pacemaking Kusurlarını Belirlemek için Sinoatrial Düğüm Ateşleme Hızının Mikroelekrod Dizisi Kaydı

The sinoatrial node (SAN), located in the right atrium, contains the pacemaker cells of the heart, and dysfunction of this region can cause tachycardia or ...

Isolation of Human Ventricular Cardiomyocytes from Vibratome-Cut Myocardial Slices

The isolation of ventricular cardiac myocytes from animal and human hearts is a fundamental method in cardiac research. Animal cardiomyocytes are commonly isolated by coronary perfusion with digestive enzymes. However, isolating human cardiomyocytes is challenging because human myocardial specimens usually do not allow for coronary perfusion, and alternative isolation protocols result in poor yields of viable cells. In addition, human myocardial specimens are rare and only regularly available at institutions with on-site cardiac surgery. This hampers the translation of findings from animal to human cardiomyocytes. Described here is a reliable protocol that enables efficient isolation of ventricular myocytes from human and animal myocardium. To increase the surface-to-volume ratio while minimizing cell damage, myocardial tissue slices 300 &#181;m thick are generated from myocardial specimens with a vibratome. Tissue slices are then digested with protease and collagenase. Rat myocardium was used to establish the protocol and quantify yields of viable, calcium-tolerant myocytes by flow-cytometric cell counting. Comparison with the commonly used tissue-chunk method showed significantly higher yields of rod-shaped cardiomyocytes (41.5 &#177; 11.9 vs. 7.89 &#177; 3.6%, p &#60; 0.05). The protocol was translated to failing and non-failing human myocardium, where yields were similar as in rat myocardium and, again, markedly higher than with the tissue-chunk method (45.0 &#177; 15.0 vs. 6.87 &#177; 5.23 cells/mg, p &#60; 0.05). Notably, with the protocol presented it is possible to isolate reasonable numbers of viable human cardiomyocytes (9&#8211;200 cells/mg) from minimal amounts of tissue (&#60;50 mg). Thus, the method is applicable to healthy and failing myocardium from both human and animal hearts. Furthermore, it is possible to isolate excitable and contractile myocytes from human tissue specimens stored for up to 36 h in cold cardioplegic solution, rendering the method particularly useful for laboratories at institutions without on-site cardiac surgery.

Presented is a protocol for the isolation of human and animal ventricular cardiomyocytes from vibratome-cut myocardial slices. High yields of calcium-tolerant cells (up to 200 cells/mg) can be obtained from small amounts of tissue (&#60;50 mg). The protocol is applicable to myocardium exposed to cold ischemia for up to 36 h.

Vibratome-Cut Miyokardiyal Dilimlerden İnsan Ventriküler Kardiyomiyositlerin İzolasyon

The isolation of ventricular cardiac myocytes from animal and human hearts is a fundamental method in cardiac research. Animal cardiomyocytes are commonly ...

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

Mouse models play a crucial role in arrhythmia research and allow studying key mechanisms of arrhythmogenesis including altered ion channel function and calcium handling. For this purpose, atrial or ventricular cardiomyocytes of high quality are necessary to perform patch-clamp measurements or to explore calcium handling abnormalities. However, the limited yield of high-quality cardiomyocytes obtained by current isolation protocols does not allow both measurements in the same mouse. This article describes a method to isolate high-quality murine atrial and ventricular myocytes via retrograde enzyme-based Langendorff perfusion, for subsequent simultaneous measurements of calcium transients and L-type calcium current from one animal. Mouse hearts are obtained, and the aorta is rapidly cannulated to remove blood. Hearts are then initially perfused with a calcium-free solution (37 &#176;C) to dissociate the tissue at the level of intercalated discs and afterwards with an enzyme solution containing little calcium to disrupt extracellular matrix (37 &#176;C). The digested heart is subsequently dissected into atria and ventricles. Tissue samples are chopped into small pieces and dissolved by carefully pipetting up and down. The enzymatic digestion is stopped, and cells are stepwise reintroduced to physiologic calcium concentrations. After loading with a fluorescent Ca2+-indicator, isolated cardiomyocytes are prepared for simultaneous measurement of calcium currents and transients. Additionally, isolation pitfalls are discussed and patch-clamp protocols and representative traces of L-type calcium currents with simultaneous calcium transient measurements in atrial and ventricular murine myocytes isolated as described above are provided.

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

Mouse models allow studying key mechanisms of arrhythmogenesis. For this purpose, high quality cardiomyocytes are necessary to perform patch-clamp measurements. Here, a method to isolate murine atrial and ventricular myocytes via retrograde enzyme-based Langendorff perfusion, which allows simultaneous measurements of calcium-transients and L-type calcium current, is described.

Ca2+ geçici ve L-tipi kalsiyum akımının eşzamanlı ölçümleri için yüksek kaliteli murin atriyal ve ventriküler miyositlerin izolasyonu

Mouse models play a crucial role in arrhythmia research and allow studying key mechanisms of arrhythmogenesis including altered ion channel function and ...

Generation of Porcine Ventricular Slices: A Vibratome-based Technique to Prepare Ultra-thin Slices of Pig Heart Tissue

Source: Ou, Q. et. al., <a href="https://www.jove.com/v/60913">Slicing and Culturing Pig Hearts under Physiological Conditions.</a> J. Vis. Exp. (2020)
This video demonstrates a vibratome-based procedure to generate viable, ultra-thin sections of pig heart. The prepared tissue slices can be cultured and used as model systems for pharmacological testing.

Domuz Ventriküler Dilimlerinin Oluşturulması: Ultra İnce Domuz Kalp Dokusu Dilimleri Hazırlamak İçin Vibratom Bazlı Bir Teknik

Source: Ou, Q. et. al., Slicing and Culturing Pig Hearts under Physiological Conditions. J. Vis. Exp. (2020)
This video demonstrates a vibratome-based ...