Name: impact of intracardiac neurons on cardiac electrophysiology and arrhythmogenesis in an ex vivo langendorff system
Uploaded: 2018-05-22T14:00:00
Description: Watch this Scientific Journal Video about Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System at JoVE.com

The authors would like to thank Hartwig Wieboldt for his excellent technical assistance, and the UKE Microscopy Imaging Facility (Umif) of the University Medical Center Hamburg-Eppendorf for providing microscopes and support. This research was funded bythe F&#246;rderverein des Universit&#228;ren Herzzentrums Hamburg e.V. and by the DZHK (German Centre for Cardiovascular Research) [FKZ 81Z4710141].

All procedures involving animals were approved by the local authorities of the State of Hamburg, the University of Hamburg Animal Care and Use Committees.
1. Preparation of the Langendorff Apparatus
NOTE: A commercially available Langendorff perfusion system is used.
<ol>
	<li>Prepare a modified Krebs-Henseleit solution (119 mM of sodium chloride, 25 mM of sodium bicarbonate, 4.6 mM of potassium chloride, 1.2 mM of potassium phosphate monobasic, 1.1 mM of magnesiu...

<ol>
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In this manuscript, the well-known Langendorff ex vivo heart perfusion system is presented as a tool to study the impact of intracardiac neurons on cardiac electrophysiology and arrhythmogenesis by using different mapping and stimulation techniques including endocardial and epicardial approaches.
Several parts of the protocol are crucial for the setup. First, it is important to use a preparation technique in which the atrial fat pads stay intact or are removed quickly without injuring...

The Langendorff ex vivo heart perfusion system continues to be a relevant tool for performing a broad spectrum of physiological, biochemical, morphological, and pharmacological studies in centrally denervated hearts1,2,3,4,5 since its invention in the late 19th century6. To date, this system is still widely used for various topics (e.g., ischemia reperfusion) or to study cardiac pharmacological effects7,8, and is a basic tool in cardiovascular research. The longevity of this method results from several advantages (e.g., measurements are performed without the influence of the central nervous system or other organs, systemic circulation, or circulating hormones). If needed, pharmaceuticals can be added in a controlled manner to the perfusion buffer or applied to specific structures directly. Experiments are reproducible, and a relatively high number of experiments can be performed in a short period of time. The (in part) open nature of the setup can make temperature regulation difficult and needs to be taken into account. Although the Langendorff system is also used in larger species9, smaller animals are primarily used as the experimental setup is less complex, and a greater biological variability (e.g., transgenic mouse models) can be used.
In the experimental setup of this protocol, the influence of the intracardiac autonomic nervous system on basic electrophysiological parameters, ventricular arrhythmogenesis, epicardial conduction, and cyclic adenosine monophosphate (cAMP) dynamics is evaluated. A large number of intracardiac ganglia, which are mainly located in the atrial fat pads and are now well known to control cardiac electrophysiology independent from central neural control, are either left intact or manually removed with careful mechanical dissection. A pharmacological modulation of the autonomic nervous system is performed either globally by adding pharmaceuticals to the perfusion buffer or locally by targeted modulation of the atrial ganglia. After the experiments, the hearts are well suited for an immunohistological assessment as all blood cells have been removed due to the continuous perfusion, which can increase the quality of staining.
The overall goal of the described techniques is to offer novel perspectives for detailed studies regarding the impact of the autonomic nervous system on cardiac electrophysiology and arrhythmogenesis in the mouse heart. A reason to use this technique is that it is possible to study and alter the autonomic nervous system without the impact of the central nervous system. One major advantage is the easy employment of pharmacological experiments, in which potential pro- or antiarrhythmic properties of old and new agents can be tested. In addition, transgenic and knockout mouse models of various cardiac diseases are available to investigate the mechanisms underlying arrhythmias, heart failure, or metabolic diseases. This approach has enhanced our understanding of how the autonomic nervous system on the atrial level can impact ventricular cardiac electrophysiology and the induction of arrhythmias.

<table>
	<tbody>
		<tr>
			<td>Sodium chloride</td>
			<td>Sigma-Aldrich</td>
			<td>S3014</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Sodium hydrogencarbonate</td>
			<td>Sigma-Aldrich</td>
			<td>401676</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Sigma-Aldrich</td>
			<td>P5405</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic</td>
			<td>Sigma-Aldrich</td>
			<td>P5655</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Magnesium sulfate heptahydrate</td>
			<td>Sigma-Aldrich</td>
			<td>M1880</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Calcium chloride dihydrate</td>
			<td>Sigma-Aldrich</td>
			<td>C7902</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G5767</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Sodium pyruvate bioXtra</td>
			<td>Sigma-Aldrich</td>
			<td>P8574</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Carbogen (95% O2 / 5% CO2)</td>
			<td colspan="2">SOL-Group, TMG Technische und Medizinische Gas GmbH, Krefeld, Gersthofen, Germany</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Sterile filter steritop-GP 0.22</td>
			<td>EMD Millipore</td>
			<td>SCGPT05RE</td>
			<td>Modified Krebs-Henleit solution</td>
		</tr>
		<tr>
			<td>Atropine sulfate</td>
			<td>Sigma-Aldrich</td>
			<td>A0257</td>
			<td>Neuromodulation</td>
		</tr>
		<tr>
			<td>Hexamethonium chloride</td>
			<td>Sigma-Aldrich</td>
			<td>H2138</td>
			<td>Neuromodulation</td>
		</tr>
		<tr>
			<td>Nicotine free base 98-100%</td>
			<td>Sigma-Aldrich</td>
			<td>N3876</td>
			<td>Neuromodulation</td>
		</tr>
		<tr>
			<td>Formalin solution neutral buffered 10%</td>
			<td>Sigma-Aldrich</td>
			<td>HT501128</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Tris(hydroxymethyl)aminomethane</td>
			<td>Sigma-Aldrich</td>
			<td>252859</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Sigma-Aldrich</td>
			<td>34860</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Hydrogen peroxide solution 30% (w/w) in H2O</td>
			<td>Merck, KGA, Darmstadt, Germany</td>
			<td>H1009</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide</td>
			<td>Merck, KGA, Darmstadt, Germany</td>
			<td>D8418</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Phosphate-buffered saline tablets</td>
			<td>Gibco / Invitrogen</td>
			<td>18912-014</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Triton-x-100</td>
			<td>Sigma-Aldrich</td>
			<td>T8787</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Albumin bovine fraction V</td>
			<td>Biomol, Hamburg, Germany</td>
			<td>11924.03</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Chicken anti neurofilament</td>
			<td>EMD Millipore</td>
			<td>AB5539</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Rabbit anti tyrosine hydroxylase</td>
			<td>EMD Millipore</td>
			<td>AB152</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Goat anti choline acetyltransferase</td>
			<td>EMD Millipore</td>
			<td>AP144P</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Donkey &#945; rabbit IgG Alexa 488</td>
			<td>Thermo Fisher Scientific</td>
			<td>A21206</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Donkey &#945; goat IgG Alexa 568</td>
			<td>Thermo Fisher Scientific</td>
			<td>A11057</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Donkey &#945; chicken IgY Alexa 647</td>
			<td>Merck, KGA, Darmstadt, Germany</td>
			<td>AP194SA6</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Biotin-conjugated donkey &#945; rabbit igG</td>
			<td>R&#38;D Systems</td>
			<td>AP182B</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Biotin-conjugated donkey &#945; goat igG</td>
			<td>R&#38;D Systems</td>
			<td>AP192P</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Biotin-conjugated goat &#945; chicken igY</td>
			<td>R&#38;D Systems</td>
			<td>BAD010</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>Vectashield mounting medium</td>
			<td>Vector laboratories, Burlingame, CA, USA</td>
			<td>H-1000</td>
			<td>Immunohistochemistry</td>
		</tr>
		<tr>
			<td>Vectastain ABC kit</td>
			<td>Vector laboratories, Burlingame, CA, USA</td>
			<td>PK-4000</td>
			<td>Immunohistochemistry</td>
		</tr>
		<tr>
			<td>Steady DAB/Plus</td>
			<td>Abcam plc, Cambridge, UK</td>
			<td>ab103723</td>
			<td>Whole mount staining</td>
		</tr>
		<tr>
			<td>HistoClear</td>
			<td>DiaTec, Bamberg, Germany</td>
			<td>HS2002</td>
			<td>Immunohistochemistry</td>
		</tr>
		<tr>
			<td>BisBenzimide H33342 trihydrochloride (Hoechst)</td>
			<td>Sigma-Aldrich, St. Louis, MO, USA</td>
			<td>B2261</td>
			<td>Immunohistochemistry</td>
		</tr>
		<tr>
			<td>Vectashield HardSet mounting medium</td>
			<td>Vector laboratories, Burlingame, CA, USA</td>
			<td>VEC-H-1400</td>
			<td>Immunohistochemistry</td>
		</tr>
		<tr>
			<td>Perfusion system</td>
			<td>HUGO SACHS ELEKTRONIK - HARVARD APPARATUS GmbH, March-Hugstetten, Germany</td>
			<td>&#160;73-4343</td>
			<td>Langendorff apparatus</td>
		</tr>
		<tr>
			<td>Data acquisition system and corresponding software for catheter and physiological parameter</td>
			<td>Powerlab 8/30 &#38; Labchart, ADInstruments, Dunedin, New Zealand</td>
			<td>PL3508 PowerLab 8/35</td>
			<td>Langendorff setup</td>
		</tr>
		<tr>
			<td>Octapolar catheter</td>
			<td>CIB&#8217;ER Mouse, NuMed Inc., Hopkinton, NY, USA</td>
			<td>custom</td>
			<td>Langendorff setup</td>
		</tr>
		<tr>
			<td>Stimulus generator</td>
			<td>STG4002, Multi Channel Systems, Reutlingen, Germany</td>
			<td>STG4002-160&#181;A</td>
			<td>Stimulation setup</td>
		</tr>
		<tr>
			<td>Stimulation software</td>
			<td>Multi Channel Systems, Reutlingen, Germany</td>
			<td>MC_Stimulus II</td>
			<td>Stimulation setup</td>
		</tr>
		<tr>
			<td>Data acquisition system and corresponding software for epicardial electrograms</td>
			<td>ME128-FAI-MPA-System, Multi Channel Systems, Reutlingen, Germany</td>
			<td>USB-ME128-System</td>
			<td>MEA setup</td>
		</tr>
		<tr>
			<td>Multi-electrode array</td>
			<td>MEA, EcoFlexMEA36, Multi Channel Systems, Reutlingen, Germany</td>
			<td>EcoFlexMEA36</td>
			<td>MEA setup</td>
		</tr>
		<tr>
			<td>Multi-electrode array recording software</td>
			<td>Multi Channel Systems, Reutlingen, Germany</td>
			<td>MC_Rack</td>
			<td>MEA setup</td>
		</tr>
		<tr>
			<td>Spring scissors</td>
			<td>Fine Science Tools GmbH, Heidelberg, Germany</td>
			<td>15003-08</td>
			<td>Heart Preparation</td>
		</tr>
		<tr>
			<td>Strabismus Scissors</td>
			<td>Fine Science Tools GmbH, Heidelberg, Germany</td>
			<td>14575-09</td>
			<td>Heart Preparation</td>
		</tr>
		<tr>
			<td>Mayo Scissors</td>
			<td>Fine Science Tools GmbH, Heidelberg, Germany</td>
			<td>14110-15</td>
			<td>Heart Preparation</td>
		</tr>
		<tr>
			<td>Dumont SS Forceps</td>
			<td>Fine Science Tools GmbH, Heidelberg, Germany</td>
			<td>11203-25</td>
			<td>Heart Preparation</td>
		</tr>
		<tr>
			<td>London Forceps</td>
			<td>Fine Science Tools GmbH, Heidelberg, Germany</td>
			<td>11080-02</td>
			<td>Heart Preparation</td>
		</tr>
		<tr>
			<td>Narrow Pattern Forceps</td>
			<td>Fine Science Tools GmbH, Heidelberg, Germany</td>
			<td>11003-13</td>
			<td>Heart Preparation</td>
		</tr>
		<tr>
			<td>Plastic Wrap</td>
			<td>Parafilm M, Bemis NA, based in Neenah, WI, United States</td>
			<td></td>
			<td>Consumable Materials</td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Leica M165FC; Leica Microsystems GmbH, Wetzlar, Germany</td>
			<td></td>
			<td>FRET</td>
		</tr>
		<tr>
			<td>LED</td>
			<td>CoolLED, Andover, UK</td>
			<td>pE-100</td>
			<td>FRET</td>
		</tr>
		<tr>
			<td>DualView</td>
			<td>Photometrics, Tucson, AZ, USA</td>
			<td>DV2-SYS</td>
			<td>FRET</td>
		</tr>
		<tr>
			<td>DualView filter set</td>
			<td>Photometrics, Tucson, AZ, USA</td>
			<td>05-EM</td>
			<td>FRET</td>
		</tr>
		<tr>
			<td>optiMOS scientific CMOS camera</td>
			<td>Qimaging, Surrey, BC, Canada</td>
			<td>01-OPTIMOS-R-M-16-C</td>
			<td>FRET</td>
		</tr>
		<tr>
			<td>Imaging software &#160;</td>
			<td>Micro-Manager; Vale Lab, University of California San Francisco, CA, USA</td>
			<td></td>
			<td>FRET</td>
		</tr>
		<tr>
			<td>Analysis Software</td>
			<td>Image J software; Public Domain, NIH, USA</td>
			<td></td>
			<td>FRET</td>
		</tr>
	</tbody>
</table>

impact of intracardiac neurons on cardiac electrophysiology and arrhythmogenesis in an ex vivo langendorff system

Since its invention in the late 19th century, the Langendorff ex vivo heart perfusion system continues to be a relevant tool for studying a broad spectrum of physiological, biochemical, morphological, and pharmacological parameters in centrally denervated hearts. Here, we describe a setup for the modulation of the intracardiac autonomic nervous system and the assessment of its influence on basic electrophysiology, arrhythmogenesis, and cyclic adenosine monophosphate (cAMP) dynamics. The intracardiac autonomic nervous system is modulated by the mechanical dissection of atrial fat pads-in which murine ganglia are located mainly&#8212;or by the usage of global as well as targeted pharmacological interventions. An octapolar electrophysiological catheter is introduced into the right atrium and the right ventricle, and epicardial-placed multi-electrode arrays (MEA) for high-resolution mapping are used to determine cardiac electrophysiology and arrhythmogenesis. F&#246;rster resonance energy transfer (FRET) imaging is performed for the real-time monitoring of cAMP levels in different cardiac regions. Neuromorphology is studied by means of antibody-based staining of whole hearts using neuronal markers to guide the identification and modulation of specific targets of the intracardiac autonomic nervous system in the performed studies. The ex vivo Langendorff setup allows for a high number of reproducible experiments in a short time. Nevertheless, the partly open nature of the setup (e.g., during MEA measurements) makes constant temperature control difficult and should be kept to a minimum. This described method makes it possible to analyze and modulate the intracardiac autonomic nervous system in decentralized hearts.

Figure 1 shows an image of the Langendorff setup including 2 multi-electrode arrays (MEAs). Before the experiment, the intracardiac catheter is positioned close to the cannula to facilitate a quick and easy insertion in the right atrium/right ventricle and to ensure a short time period until the equilibration can start. The lower part of the chamber can be heightened (see the arrows in Figure 1) so that the chamber is fully close...

Watch this Scientific Journal Video about Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System at JoVE.com

Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System

Here, we present a protocol for the modulation of the intracardiac autonomic nervous system and the assessment of its influence on basic electrophysiology, arrhythmogenesis, and cAMP dynamics using an ex vivo Langendorff setup.

Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System

Since its invention in the late 19th century, the Langendorff ex vivo heart perfusion system continues to be a relevant tool for studying a broad spectrum ...

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