This study was supported by Taiwan Ministry of Science and Technology grants MOST 104-2314-B-037-080-MY3 and MOST 107-2314-B-037-110 to HCL and Taiwan National Health Research Institutes grant NHRI-EX107-10724SC.

All the animal experiments described were approved by the Institutional Animal Care and Use Committee of Kaohsiung Medical University.
1. Animal Care
<ol>
	<li>To avoid difficult cannulation due to small arterial size, use rats with body weight over 200 g.</li>
	<li>Remove chow from the cage and fast rats overnight.</li>
	<li>Offer water ad libidum unless there is a special experimental design.</li>
</ol>
2. Experimental Preparation
<ol>
	<li>Obtain the following materials: forceps with teeth (Figure 1A), surgical scissors (Figure 1B), forceps with fine tips (Figure 1C, 1D), forceps with angled tips (Figure 1E), bulldog vascular clamp (Figure 1F), silk string approximately 20 cm in length (Figure 1G), micro scissors (Figure 1H), intra-arterial cannula, a sterile polyethylene (PE) tube with an internal diameter of 0.5 mm and an outer diameter of 0.9 mm, 25&#8211;30 cm in length, connected to a 26 G x 1/2&#8217;&#8217; needle (Figure 1I), two three-way stopcocks (Figure 1J) for connecting the intra-arterial cannula and the pressure transducer (Figure 1K), and 1 mL syringes filled with heparinized saline (100 IU/mL).</li>
	<li>Animal Preparation
	<ol>
		<li>Anesthetize the rat by inhalation of isoflurane (placing the rats in a 25 cm x 25 cm x 14&#8201;cm induction chamber saturated with 4% isoflurane, followed by nosecone use with 3% isoflurane). 
		NOTE: If the animal is not sufficiently anesthetized, turn up the flow rate of isoflurane.</li>
		<li>Test the pain reflex by pinching the toes.</li>
		<li>Place the rat in a supine position on a pre-cut Styrofoam board (or thick cardboard). Fix the four legs with rubber bands to immobilize the body (Figure 2A). 
		NOTE: To avoid potential noise during the ECG recording, the placement surface must not be electrically conductive.</li>
	</ol>
	</li>
	<li>Prepare instruments for BP and ECG recording. Include an analog input unit to acquire signals, a pressure transducer with a compatible hub, three bipolar needle-tipped electrocardiogram leads, and a computer with suitable software.</li>
</ol>
3. Pressure Transducer Calibration
<ol>
	<li>Before initiation of BP recording, calibrate with a standard mercury sphygmomanometer (Figure 1L).</li>
	<li>Remove the pressure cuff from the sphygmomanometer and connect the three-way stopcock on the inflation tube to the pressure transducer (Figure 1K) of the data acquisition system.</li>
	<li>Screw the air-release valve clockwise. Keep eyes on the gauge and keep pumping the inflation bulb. When the gauge shows 100 mmHg, switch the three-way stopcock to connect to the pressure transducer. Use 100 mmHg pressure for the calibration. The conversion factor for calculating BP will be determined automatically.</li>
	<li>Release the pressure by screwing the air-release valve counterclockwise until the pressure of the sphygmomanometer is back to zero.</li>
	<li>Repeat step 3.2 with pressure of 200 mmHg.</li>
	<li>Detach the pressure transducer from the mercury sphygmomanometer.</li>
	<li>Connect the pressure transducer to the three-way stopcock of the PE catheter (Figure 1I).</li>
</ol>
4. Mini-surgery for Cannulation of the Femoral Artery
<ol>
	<li>Surface landmark identification and excision of the skin (Figure 2)
	<ol>
		<li>Identify the location of inguinal crease (indentation at the junction between abdomen and thigh) (dashed line in Figure 2A).</li>
		<li>Pinch the full layer of skin at the center of the inguinal crease.&#160;The fur may be shaved or removed from the incision site using electric clippers or a depilatory cream prior to incision.</li>
		<li>Lift the skin and cut it off with the surgical scissors at an orientation approximately parallel to the ipsilateral thigh (Figure 2B). The femoral nerve and vessels are underneath the exposed subcutaneous tissue (Figure 2C).</li>
	</ol>
	</li>
	<li>Dissection of the tissue to expose the femoral artery
	<ol>
		<li>Dissect the tissue using forceps with fine tips, layer by layer. Stop the dissection at the level of femoral vessels. Make sure the dissection is not injuring the vessels underneath.</li>
		<li>Carefully use forceps (Figure 1C or 1D) to clear out the soft tissue along the femoral nerve and vessels to obtain good observation. The nerve is fiber-like in texture. The vein is dark purple and the artery is pulsatile (Figure 3A).</li>
		<li>Use forceps with angled tips (Figure 1E) to extend the exposed length of the femoral artery and vein (Figure 3B).</li>
	</ol>
	</li>
	<li>Cannulation of the femoral artery (Figure 3)
	<ol>
		<li>Use forceps to separate the femoral vein from the artery and apply a bulldog clamp at the femoral artery as cranially as possible (Figure 3C).</li>
		<li>Make a loose tie of the two silk strings, one just below the bulldog clamp and the other at the caudal terminal of the exposed femoral artery (Figure 3D).</li>
		<li>Make a small hole over the ventral side of the femoral artery (Figure 3E) using the micro scissors (Figure 1H).</li>
		<li>Insert the tip of the PE catheter through the small hole and advance the catheter cranially. 
		NOTE: Do not apply torsion while advancing the PE catheter. The torsion force may twist the femoral artery and result in luminal stenosis.</li>
		<li>Remove the bulldog clamp after the PE catheter is securely advanced into the femoral artery lumen. 
		NOTE:&#160;Keep eyes on the PE catheter while removing the bulldog clamp from the femoral artery. The observation of a backflush of blood into the PE catheter associated with observation for pulse confirms its placement in the arterial lumen.&#160;&#160;</li>
		<li>Tighten the upper silk string to secure the position of the PE catheter. 
		NOTE: Any accidental pull or dislocation of the PE catheter can result in major bleeding.</li>
		<li>Tighten the lower silk string to prevent bleeding from the caudal side of the femoral artery.</li>
	</ol>
	</li>
	<li>Confirmation of the success of femoral artery cannulation
	<ol>
		<li>Use a 1 mL syringe to inject 0.1&#8211;0.2 mL of heparinized saline into the femoral artery. The resistance on injection must be trivial. If any obvious resistance upon injection is noticed, check the whole cannulation again. 
		NOTE: Make sure the three-way stopcocks are appropriately switched before applying any negative pressure or saline injection into the femoral artery cannula. At this time point, any injection into the pressure transducer will need a re-calibration.</li>
		<li>Check if there is any oozing around the cannulation site. If not, cover the surgical site with a wet cotton ball.</li>
	</ol>
	</li>
</ol>
5. Recording of Blood Pressure
<ol>
	<li>After a smooth flush for the PE catheter, attach the PE catheter three-way stopcock to the one on the pressure transducer (Figure 4).</li>
	<li>Make sure that there are no air bubbles in the cannulation system. Also check the connection junctions of the three-way stopcock.</li>
	<li>Start the data acquisition system with sampling frequency of 1,000 Hz to record the BP. Arterial pressure waves will be demonstrated (Figure 6).</li>
	<li>Allow the whole setup to stabilize for at least 3-5 min. In cases with unsteady signals, stabilization time can be extended to 15 min.</li>
	<li>Check the cannulation site periodically to make sure there is no bleeding. 
	NOTE: When acquiring data from a pressure transducer, it is important to place the transducer at the level of the animal&#8217;s heart.</li>
</ol>
6. Surface ECG
<ol>
	<li>Check the three leads of the bipolar ECG to make sure the positive, negative, and reference platinum electrodes are intact.</li>
	<li>Insert the leads subcutaneously at the left foreleg, right foreleg, and right hindleg (Figure 5).</li>
	<li>Attach the electrode hubs to a custom-built ECG amplifier with sampling frequency of 1,000 Hz and filter frequency of 3&#8211;500 Hz. Keep ECG leads steady during recording. Motion of the ECG leads can produce unsteady baselines and artifacts.</li>
</ol>
7. Animal Euthanasia After Completing of the Experiment
<ol>
	<li>After completing of the BP and ECG recording, stop the acquisition system. Remove the electrodes. Ligate the femoral artery by tightening up the previously placed silk string right after withdrawing the PE catheter.</li>
	<li>Place the rats individually in the visible euthanasia chamber connected to compressed carbon dioxide (CO2) gas cylinders. Seal the top securely.</li>
	<li>Introduce 100% CO2 with a fill rate of about 10% to 30% of the chamber volume per minute.</li>
	<li>Keep your eyes on the rat; lack of respiration and faded eye color should appear within 2&#8722;3 min. 
	NOTE: If cessation of respiratory movement&#160;does not occur after 3 min, the system should be examined for the chamber fill rate, CO2 supply, or leaks.</li>
	<li>Maintain CO2 flow to the chamber for 1 more minute after respiration ceases.</li>
	<li>Ascertain cardiac and respiratory arrest and note fixed and dilated pupils to confirm death. 
	NOTE: If the rat is not dead but in CO2 narcosis, use a secondary method of euthanasia such as bilateral thoracotomy.</li>
</ol>

<ol>
	<li>Shiou, Y. -. L., Huang, I. C., Lin, H. -. T., Lee, H. -. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+fat+diet+aggravates+atrial+and+ventricular+remodeling+of+hypertensive+heart+disease+in+aging+rats.">High fat diet aggravates atrial and ventricular remodeling of hypertensive heart disease in aging rats.</a> Journal of the Formosan Medical Association. , (2017).</li><li>Parasuraman, S., Raveendran, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+invasive+blood+pressure+in+rats.">Measurement of invasive blood pressure in rats.</a> Journal of Pharmacology, Pharmacotherapeutics. 3 (2), 172-177 (2012).</li><li>Fink, G. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+Tail-Cuff+Plethysmography+Provide+a+Reliable+Estimate+of+Central+Blood+Pressure+in+Mice?.">Does Tail-Cuff Plethysmography Provide a Reliable Estimate of Central Blood Pressure in Mice?.</a> Journal of the American Heart Association: Cardiovascular and Cerebrovascular Disease. 6 (6), e006554 (2017).</li><li>Wilde, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tail-Cuff+Technique+and+Its+Influence+on+Central+Blood+Pressure+in+the+Mouse.">Tail-Cuff Technique and Its Influence on Central Blood Pressure in the Mouse.</a> Journal of the American Heart Association: Cardiovascular and Cerebrovascular Disease. 6 (6), (2017).</li><li>Braga, V. A., Prabhakar, N. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Refinement+of+Telemetry+for+Measuring+Blood+Pressure+in+Conscious+Rats.">Refinement of Telemetry for Measuring Blood Pressure in Conscious Rats.</a> Journal of the American Association for Laboratory Animal Science : JAALAS. 48 (3), 268-271 (2009).</li><li>Kaese, S., Verheule, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+electrophysiology+in+mice:+a+matter+of+size.">Cardiac electrophysiology in mice: a matter of size.</a> Frontiers in Physiology. 3 (345), (2012).</li><li>Okamoto, K., Aoki, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+strain+of+spontaneously+hypertensive+rats.">Development of a strain of spontaneously hypertensive rats.</a> Japanese Circulation Journal. 27, 282-293 (1963).</li><li>Van Vliet, B. N., Chafe, L. L., Antic, V., Schnyder-Candrian, S., Montani, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+and+indirect+methods+used+to+study+arterial+blood+pressure.">Direct and indirect methods used to study arterial blood pressure.</a> Journal of Pharmacological and Toxicological Methods. 44 (2), 361-373 (2000).</li><li>Alam, M. A., Parks, C., Mancarella, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+Blood+Pressure+Measurement+in+Freely+Moving+Mice+Using+Telemetry.">Long-term Blood Pressure Measurement in Freely Moving Mice Using Telemetry.</a> Journal of Visualized Experiments. (111), e53991 (2016).</li><li>Irvine, R. J., White, J., Chan, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+restraint+on+blood+pressure+in+the+rat.">The influence of restraint on blood pressure in the rat.</a> Journal of Pharmacological and Toxicological Methods. 38 (3), 157-162 (1997).</li><li>Nvd Vosse, F., Stergiopulos, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulse+Wave+Propagation+in+the+Arterial+Tree.">Pulse Wave Propagation in the Arterial Tree.</a> Annual Review of Fluid Mechanics. 43 (1), 467-499 (2011).</li><li>Cosson, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aortic+stiffness+and+pulse+pressure+amplification+in+Wistar-Kyoto+and+spontaneously+hypertensive+rats.">Aortic stiffness and pulse pressure amplification in Wistar-Kyoto and spontaneously hypertensive rats.</a> The American Journal of Physiology: Heart and Circulatory Physiology. 292 (5), H2506-H2512 (2007).</li></ol>

The authors have nothing to disclose.

Invasive arterial cannulation allows highly accurate measurement of BP. It can be done with a PE tube without requiring an expensive catheter. Invasive BP measurement can also be performed simultaneously with a recording of the surface ECG.
The major learning curve for this method is the experimental skill required to cannulate small blood vessels. In experienced hands, the successful rate for femoral artery cannulation can approach 100%. Practice is recommended before performing real&#160;exp...

Blood pressure (BP) and electrocardiography (ECG) are basic parameters for cardiovascular physiology and medicine. Experimental animal models have been widely applied in biomedical research for various cardiovascular diseases such as hypertensive heart failure1 and procedures for ECG recording and BP measurement can be performed in experimental rats.
There are three methods for BP measurement in rats: intra-arterial cannulation (invasive)2, tail cuff plethysmography (noninvasive)3, and radio telemetry (invasive). The reliability of BP measurement by tail cuff plethysmography can be affected by animal handling during the recording. For example, the tail cuff underestimates the core BP changes that occur simultaneously during the restraint and measurement phases4. Radio telemetry is considered the best &#34;gold standard&#34; technique for monitoring BP and heart rate in awake and freely moving animals5. However, since radio telemetry hardware and software are costly, intra-arterial cannulation is also widely used as an economical alternative.
Intra-arterial cannulation requires considerable microsurgical skill but yields the real waveforms of arterial pressure. BP can be recorded through a saline-filled catheter inserted in the radial, femoral, or brachial artery. This method of direct invasive BP measurement requires pre-surgical animal preparation, anesthesia, immobilization of laboratory animals, surgical skill in tissue dissection and arterial cannulation, and proper calibration before acquiring the measurement.
Rodent surface ECG is similar to human ECG. A rat ECG has sequences of P waves, QRS complexes, T waves, and QT intervals6. The P wave, PR interval, QRS complex, and T waves reflect atrial depolarization, impulse conduction from the atrial to the AV node, ventricular depolarization, and repolarization, respectively. The QT interval is defined as the period from the initiation of the Q wave to the end-point of the T wave where it returns to the iso-electrical baseline1.
The ECG indicates the cardiac systole and diastole phases; therefore, the simultaneous recording of the surface ECG correlates with the invasive BP measurement. By using a combination of methodologies, it is possible to elucidate pathophysiological changes in a disease model or the pharmacological effects of a drug or therapy in cardiovascular medicine.
A spontaneous hypertensive rat (SHR) strain had been obtained by inbreeding of Wistar rats with high BP in Japan. The BP rises from 5 to 10 weeks of age and becomes stationary from 30 to 35 weeks of age7. Wistar-Kyoto rats (WKY) have systolic BP about 130 mmHg7 and are commonly used as normo-tensive control. We used SHR and WKY to demonstrate the result of intraarterial cannulation BP and ECG recording.

<table><tbody><tr><td>Polyethylene tube</td><td>BECTON DICKINSON</td><td>427401</td><td>internal diameter of 0.5 mm, outer diameter of 0.9 mm</td></tr><tr><td>26 G x 1/2&quot;&quot; needle</td><td>TERUMO</td><td>160426D</td><td></td></tr><tr><td>Adson Forceps</td><td>TOP Line</td><td>12-540</td><td>12 cm (4.75&quot;) Long, Straight, 1 x 2 Teeth</td></tr><tr><td>Bulldog vascular clamp</td><td>Teleflex</td><td>357581</td><td>8 mm</td></tr><tr><td>Computer&amp;nbsp;</td><td>AUSUS</td><td>X453M</td><td></td></tr><tr><td>Exernal analog signal recording device</td><td>iWorx</td><td>T5141538</td><td>This allows the recording of up to three channels of ECG, EMG or EEG as well as GSR (skin conductance) from a single iWire input on the recording Module.</td></tr><tr><td>Graefe Forceps</td><td>AESCULAP Surgical Instruments</td><td>BD312R</td><td>MICRO DRESSING FORCEPS, CURVED, SERRATED, 105 mm, 4 1/8&amp;nbsp;</td></tr><tr><td>Mecury sphygmomanometer</td><td>Spirit</td><td>CK-101</td><td></td></tr><tr><td>Pressure transducer</td><td>iWorx</td><td>IworxBP100</td><td></td></tr><tr><td>Semken Forceps</td><td>MEDE TECHNIK</td><td>10-104</td><td>100 mm</td></tr><tr><td>Software</td><td>LabScribe3</td><td></td><td></td></tr><tr><td>Surgical scissors</td><td>HEBU</td><td>1714</td><td>14.5 cm long</td></tr><tr><td>Syringe (1 mL)</td><td>TERUMO</td><td>160426D</td><td></td></tr><tr><td>Three-way stopcocks</td><td>Cole-Parmer</td><td>EW-30600-23</td><td></td></tr><tr><td>Tipped forceps</td><td>World Precision Instruments</td><td>504506</td><td>11 cm long, 0.1 x 0.06 mm Tips</td></tr><tr><td>Vannas Scissors</td><td>World Precision Instruments</td><td>500086</td><td>8.5 cm long, Straight, 0.025 x 0.015 mm Tips, 7mm super fine Blades</td></tr></tbody></table>

simultaneous electrocardiography recording and invasive blood pressure measurement in rats

For studies related to cardiovascular physiology or pathophysiology, blood pressure (BP) and electrocardiography are basic observational parameters. Research focusing on cardiovascular disease models, potential cardiovascular therapeutic targets or pharmaceutical agents requires assessment of systemic arterial pressure and heart rhythm changes. In situations where radio telemetry systems are not available or affordable, the technique of femoral artery cannulation is an alternative way to obtain intra-arterial pressure waveform recordings and systemic BP measurements. This technique is economical and can be performed with standard equipment in animal facilities. However, invasive arterial pressure recording requires cannulation of small arteries, which can be a challenging surgical skill. Here, we present step-by-step protocols for femoral artery cannulation procedures. Key procedures include the calibration of the data acquisition system, tissue dissection and femoral artery cannulation, and setup of the arterial cannulation system for pressure recording. Surface electrocardiography recording procedures are also included. We also present examples of BP recordings from normotensive and hypertensive rats. This protocol allows reliable direct recordings of systemic BP with simultaneous electrocardiography.

We purchased SHR and normotensive Wistar-Kyoto WKY rats from the National Laboratory Animal Center (Taipei, Taiwan). All animals were housed in a temperature-controlled facility (20&#8722;22 &#176;C) with free access to water and standard chow on a 12 h light/dark cycle.
We used six 47-week-old rats and they were weighed before the BP and ECG measurement. The representative tracings from simultaneous recording of ECG and BP in S...

Watch this Scientific Journal Video about Simultaneous Electrocardiography Recording and Invasive Blood Pressure Measurement in Rats at JoVE.com

Simultaneous Electrocardiography Recording and Invasive Blood Pressure Measurement in Rats

Here, we describe a setup for simultaneous recording of electrocardiography and intra-arterial blood pressure (BP) in experimental rats, which can be done with standard equipment in animal facilities and can be applied to physiological or pharmacological studies to investigate pathogenic or therapeutic mechanisms in cardiovascular medicine.

For studies related to cardiovascular physiology or pathophysiology, blood pressure (BP) and electrocardiography are basic observational parameters. ...

simultaneous-electrocardiography-recording-invasive-blood-pressure

Research

JoVE Journal

Medicine

15.1K Views.  Kaohsiung Medical University Hospital. Studies gericht op hart-en vaatziekten modellen, cardiovasculaire therapeutische doelen, of farmaceutische agentia vereisen de beoordeling van systemische arteriële druk en hartritme veranderingen. Femorale slagader cannulation is een economische methode voor het registreren van intraarteriële drukgolfvormen die kunnen worden uitgevoerd met standaarduitrusting in een dierenfaciliteit. Het aantonen van de procedure zal Hsin-Ting Lin zijn, een technicus van mijn laboratorium.Voordat u ...

Video: Simultaneous Electrocardiography Recording and Invasive Blood Pressure Measurement in Rats

Simultaneous Video-EEG-ECG Monitoring to Identify Neurocardiac Dysfunction in Mouse Models of Epilepsy

In epilepsy, seizures can evoke cardiac rhythm disturbances such as heart rate changes, conduction blocks, asystoles, and arrhythmias, which can potentially increase risk of sudden unexpected death in epilepsy (SUDEP). Electroencephalography (EEG) and electrocardiography (ECG) are widely used clinical diagnostic tools to monitor for abnormal brain and cardiac rhythms in patients. Here, a technique to simultaneously record video, EEG, and ECG in mice to measure behavior, brain, and cardiac activities, respectively, is described. The technique described herein utilizes a tethered (i.e., wired) recording configuration in which the implanted electrode on the head of the mouse is hard-wired to the recording equipment. Compared to wireless telemetry recording systems, the tethered arrangement possesses several technical advantages such as a greater possible number of channels for recording EEG or other biopotentials; lower electrode costs; and greater frequency bandwidth (i.e., sampling rate) of recordings. The basics of this technique can also be easily modified to accommodate recording other biosignals, such as electromyography (EMG) or plethysmography for assessment of muscle and respiratory activity, respectively. In addition to describing how to perform the EEG-ECG recordings, we also detail methods to quantify the resulting data for seizures, EEG spectral power, cardiac function, and heart rate variability, which we demonstrate in an example experiment using a mouse with epilepsy due to Kcna1 gene deletion. Video-EEG-ECG monitoring in mouse models of epilepsy or other neurological disease provides a powerful tool to identify dysfunction at the level of the brain, heart, or brain-heart interactions.

Here, we present a protocol to record brain and heart bio signals in mice using simultaneous video, electroencephalography (EEG), and electrocardiography (ECG). We also describe methods to analyze the resulting EEG-ECG recordings for seizures, EEG spectral power, cardiac function, and heart rate variability.

In epilepsy, seizures can evoke cardiac rhythm disturbances such as heart rate changes, conduction blocks, asystoles, and arrhythmias, which can ...

Genetics

Measuring Blood Pressure in Mice using Volume Pressure Recording, a Tail-cuff Method

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. The CODA tail-cuff system uses Volume Pressure Recording (VPR) to measure the blood pressure by determining the tail blood volume. A specially designed differential pressure transducer and an occlusion tail-cuff measure the total blood volume in the tail without the need to obtain the individual pulse signal. Special attention is afforded to the length of the occlusion cuff in order to derive the most accurate blood pressure readings. VPR can easily obtain readings on dark-skinned rodents, such as C57BL6 mice and is MRI compatible. The CODA system provides you with measurements of six (6) different blood pressure parameters; systolic and diastolic blood pressure, heart rate, mean blood pressure, tail blood flow, and tail blood volume. Measurements can be made on either awake or anesthetized mice or rats. The CODA system includes a controller, laptop computer, software, cuffs, animal holders, infrared warming pads, and an infrared thermometer. There are seven different holder sizes for mice as small as 8 grams to rats as large as 900 grams.

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. This tail-cuff system uses Volume Pressure Recording (VPR) to measure the blood pressure by determining the tail blood volume.

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. The CODA ...

Biology

Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats

The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the electrical responses of the retina to light stimulation, while the VEP measures the corresponding functional integrity of the visual pathways from the retina to the primary visual cortex following the same light event. The ERG waveform can be broken down into components that reflect responses from different retinal neuronal and glial cell classes. The early components of the VEP waveform represent the integrity of the optic nerve and higher cortical centers. These recordings can be conducted in isolation or together, depending on the application. The methodology described in this paper allows simultaneous assessment of retinal and cortical visual evoked electrophysiology from both eyes and both hemispheres. This is a useful way to more comprehensively assess retinal function and the upstream effects that changes in retinal function can have on visual evoked cortical function.

This protocol describes simultaneous measurement of electroretinogram and visual evoked potentials in anesthetized rats.

The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the ...

Neuroscience

Novel Approach for Simultaneous Recording of Renal Sympathetic Nerve Activity and Blood Pressure with Intravenous Infusion in Conscious, Unrestrained Mice.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity (RSNA) is of great interest in many areas of research such as chronic kidney disease, hypertension, heart failure, diabetes and obesity. Unequivocal assessment of the role of the sympathetic nervous system is thus imperative for proper interpretation of experimental results and understanding of disease processes. RSNA has been traditionally measured in anesthetized rodents, including mice. However, mice usually exhibit very low systemic blood pressure and hemodynamic instability for several hours during anesthesia and surgery. Meaningful interpretation of RSNA is confounded by this non-physiological state, given the intimate relationship between sympathetic nervous tone and cardiovascular status. To address this limitation of traditional approaches, we developed a new method for measuring RSNA in conscious, freely-moving mice. Mice were chronically instrumented with radio-telemeters for continuous monitoring of blood pressure as well as a jugular venous infusion catheter and custom-designed bipolar electrode for direct recording of RSNA. Following a 48-72 hour recovery period, survival rate was 100% and all mice behaved normally. At this time-point, RSNA was successfully recorded in 80% of mice, with viable signals acquired up to 4 and 5 days post-surgery in 70% and 50% of mice, respectively. Physiological blood pressures were recorded in all mice (116&plusmn;2 mmHg; n=10). Recorded RSNA increased with eating and grooming, as well-established in the literature. Furthermore, RSNA was validated by ganglionic blockade and modulation of blood pressure with pharmacological agents. Herein, an effective and manageable method for clear recording of RSNA in conscious, freely-moving mice is described.

Anesthetized mice exhibit non-physiological systemic blood pressure, which precludes meaningful assessment of autonomic tone given the intimate relationship between blood pressure and the autonomic nervous system. Thus, a novel method to simultaneously record renal sympathetic nerve activity and blood pressure with intravenous infusion in conscious mice is outlined.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity ...

Simultaneous Recordings of Cortical Local Field Potentials, Electrocardiogram, Electromyogram, and Breathing Rhythm from a Freely Moving Rat

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls body functions and internal organ rhythms when animals are exposed to emotional challenges and changes in their living environments. In general experiments, signals from different organs, such as the brain and the heart, are recorded by independent recording systems that require multiple recording devices and different procedures for processing the data files. This study describes a new method that can simultaneously monitor electrical biosignals, including tens of local field potentials in multiple brain regions, electrocardiograms that represent the cardiac rhythm, electromyograms that represent awake/sleep-related muscle contraction, and breathing signals, in a freely moving rat. The recording configuration of this method is based on a conventional micro-drive array for cortical local field potential recordings in which tens of electrodes are accommodated, and the signals obtained from these electrodes are integrated into a single electrical board mounted on the animal's head. Here, this recording system was improved so that signals from the peripheral organs are also transferred to an electrical interface board. In a single surgery, electrodes are first separately implanted into the appropriate body parts and the target brain areas. The open ends of all of these electrodes are then soldered to individual channels of the electrical board above the animal's head so that all of the signals can be integrated into the single electrical board. Connecting this board to a recording device allows for the collection of all of the signals into a single device, which reduces experimental costs and simplifies data processing, because all data can be handled in the same data file. This technique will aid the understanding of the neurophysiological correlates of the associations between central and peripheral organs.

This study introduces a method for the simultaneous recording of local field potentials in the brain, electrocardiograms, electromyograms, and breathing signals of a freely moving rat. This technique, which reduces experimental costs and simplifies data analysis, will contribute to the understanding of the interactions between the brain and peripheral organs.

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls ...

Electrocardiogram Recordings in Anesthetized Mice using Lead II

The electrocardiogram is a valuable tool for evaluating the cardiac conduction system. Animal research has helped generate novel genetic and pharmacological information regarding the electrocardiogram. However, making electrocardiogram measurements in small animals in vivo, such as mice, has been challenging. To this end, we used an electrocardiogram recording method in anesthetized mice with many advantages: it is a technically simple procedure, is inexpensive, has short measuring time, and is affordable, even in young mice. Despite the limitations with using anesthesia, comparisons between control and experimental groups can be performed with enhanced sensitivity. We treated mice with agonists and antagonists of the autonomic nervous system to determine the validity of this protocol and compared our results with previous reports. Our ECG protocol detected increased heart rates and QTc intervals on treatment with atropine, decreased heart rates and QTc intervals after carbachol treatment, and higher heart rates and QTc intervals with isoprenaline but did not note any change in ECG parameters on administration of propranolol. These results are supported by previous reports, confirming the reliability of this ECG protocol. Thus, this method can be used as a screening approach to making ECG measurements that otherwise would not be attempted due to high cost and technical difficulties.

We present an ECG protocol that is technically easy, inexpensive, fast, and affordable in small mice, and can be performed with enhanced sensitivity. We suggest this method as a screening approach for studying pharmacological agents, genetic modifications, and disease models in mice.

The electrocardiogram is a valuable tool for evaluating the cardiac conduction system. Animal research has helped generate novel genetic and ...

Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. The baroreflex is a key homeostatic mechanism to counteract acute, short-term changes in arterial BP and to maintain BP in a relatively narrow physiological range. BP is sensed by baroreceptors located in the aortic arch and carotid sinus. When BP changes, signals are transmitted to the central nervous system and are then communicated to the parasympathetic and sympathetic branches of the autonomic nervous system to adjust HR. A rise in BP causes a reflex decrease in HR, a drop in BP causes a reflex increase in HR.
Baroreflex sensitivity (BRS) is the quantitative relationship between changes in arterial BP and corresponding changes in HR. Cardiovascular diseases are often associated with impaired baroreflex function. In various studies reduced BRS has been reported in e.g., heart failure, myocardial infarction, or coronary artery disease. 
Determination of BRS requires information from both BP and HR, which can be recorded simultaneously using telemetric devices. The surgical procedure is described beginning with the insertion of the pressure sensor into the left carotid artery and positioning of its tip in the aortic arch to monitor arterial pressure followed by the subcutaneous placement of the transmitter and ECG electrodes. We also describe postoperative intensive care and analgesic management. After a two-week period of post-surgery recovery long-term ECG and BP recordings are performed in conscious and unrestrained mice. Finally, we include examples of high-quality recordings and the analysis of spontaneous baroreceptor sensitivity using the sequence method.

The baroreflex is a heart-rate regulation mechanism by the autonomic nervous system in response to blood-pressure changes. We describe a surgical technique to implant telemetry transmitters for continuous and simultaneous measurement of electrocardiogram and blood pressure in mice. This can determine spontaneous baroreflex sensitivity, an important prognostic marker for cardiovascular disease.

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. ...

Multi-system Monitoring for Identification of Seizures, Arrhythmias and Apnea in Conscious Restrained Rabbits

Patients with ion channelopathies are at a high risk of developing seizures and fatal cardiac arrhythmias. There is a higher prevalence of heart disease and arrhythmias in people with epilepsy (i.e., epileptic heart.) Additionally, cardiac and autonomic disturbances have been reported surrounding seizures. 1:1,000 epilepsy patients/year die of sudden unexpected death in epilepsy (SUDEP). The mechanisms for SUDEP remain incompletely understood. Electroencephalograms (EEG) and electrocardiograms (ECG) are two techniques routinely used in the clinical setting to detect and study the substrates/triggers for seizures and arrhythmias. While many studies and descriptions of this methodology are in rodents, their cardiac electrical activity differs significantly from humans. This article provides a description of a non-invasive method for recording simultaneous video-EEG-ECG-oximetry-capnography in conscious rabbits. As cardiac electrical function is similar in rabbits and humans, rabbits provide an excellent model of translational diagnostic and therapeutic studies. In addition to outlining the methodology for data acquisition, we discuss the analytical approaches for examining neuro-cardiac electrical function and pathology in rabbits. This includes arrhythmia detection, spectral analysis of EEG and a seizure scale developed for restrained rabbits.

Using simultaneous video-EEG-ECG-oximetry-capnography, we developed a methodology to evaluate the susceptibility of rabbit models to develop provoked arrhythmias and seizures. This novel recording system establishes a platform to test the efficacy and safety of therapeutics and can capture the complex cascade of multi-system events that culminate in sudden death.

Patients with ion channelopathies are at a high risk of developing seizures and fatal cardiac arrhythmias. There is a higher prevalence of heart disease ...

Real-Time Monitoring and Modulation of Blood Pressure in a Rabbit Model of Ischemic Stroke

Control of blood pressure, in terms of both absolute values and its variability, affects outcomes in ischemic stroke patients. However, it remains challenging to identify the mechanisms that lead to poor outcomes or evaluate measures by which these effects can be mitigated because of the prohibitive limitations inherent to human data. In such cases, animal models can be utilized to conduct rigorous and reproducible evaluations of diseases. Here we report refinement of a previously described model of ischemic stroke in rabbits that is augmented with continuous blood pressure recording to assess the impacts of modulation on blood pressure. Under general anesthesia, femoral arteries are exposed through surgical cutdowns to place arterial sheaths bilaterally. Under fluoroscopic visualization and roadmap guidance, a microcatheter is advanced into an artery of the posterior circulation of the brain. An angiogram is performed by injecting the contralateral vertebral artery to confirm occlusion of the target artery. With the occlusive catheter remaining in position for a fixed duration, blood pressure is continuously recorded to allow for tight titration of blood pressure manipulations, whether through mechanical or pharmacological means. At the completion of the occlusion interval, the microcatheter is removed, and the animal is maintained under general anesthesia for a prescribed length of reperfusion. For acute studies, the animal is then euthanized and decapitated. The brain is harvested and processed to measure the infarct volume under light microscopy and further assessed with various histopathological stains or spatial transcriptomic analysis. This protocol provides a reproducible model that can be utilized for more thorough preclinical studies on the effects of blood pressure parameters during ischemic stroke. It also facilitates effective preclinical evaluation of novel neuroprotective interventions that might improve care for ischemic stroke patients.

Continuous arterial blood pressure recording allows the investigation of impacts of various hemodynamic parameters. This report demonstrates the application of continuous arterial blood pressure monitoring in a large animal model of ischemic stroke for determination of stroke pathophysiology, impact of different hemodynamic factors, and the assessment of novel treatment approaches.

Control of blood pressure, in terms of both absolute values and its variability, affects outcomes in ischemic stroke patients. However, it remains ...

Monitoring Cardiac Function of Rats Using the Pressure-Volume Conductance Technique

Real-Time Detection of Ferulic Acid Effects on Rat Left Ventricle Using Pressure-Volume Conductivity Catheter

Decreased cardiac function can have a negative impact on other organs. The left ventricular pressure-volume relationship is considered to be a valid method for evaluating cardiac function. Real-time monitoring of cardiac function is important for drug evaluation. Under closed-chest conditions, the miniature transducer, which is an important component of the pressure-volume catheter, enters the left ventricle of the rat through the right carotid artery. The device visualizes the changes in cardiac function during the experiment in the form of a pressure-volume loop. The actual volume of the ventricle is calculated by altering the conductivity of the blood by injecting 50 &#181;L of a 20% sodium chloride solution into the rat's left jugular vein. The actual volume of the rat's ventricular cavity is calculated by measuring the conductivity of the blood in a known volume using a pressure-volume conductance catheter. This protocol allows for continuous observation of the effects of drugs on the heart and will promote the rationale for the use of specialty ethnic drugs in cardiovascular disease.

Author Spotlight: Advantages of Pressure-Volume Loop Measurement Method in Cardiovascular Research

This protocol describes a method for measuring left ventricular pressure and volume using the pressure-volume conductance technique. This method enables continuous real-time monitoring of the effects of drugs on the heart.

Decreased cardiac function can have a negative impact on other organs. The left ventricular pressure-volume relationship is considered to be a valid ...

Simultaneous Electrocardiography Recording and Invasive Blood Pressure Measurement in Rats

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