The authors acknowledge generous support from the Saving tiny Hearts Society (KLT), the UNE COBRE Program (NIGMS grant number P20GM103643; LAF), and the SURE Fellowship Program at the University of New England (VLB), as well as patient technical support from Ashish More (iWorx, Dover, NH). Figure 3, Figure 4, and Figure S1 were created with Biorender software.

The following protocol follows the standards of the Institutional Animal Care and Use Committee of the University of New England. Close observation of the protocol should deliver satisfactory ECG reads in all examined neonates (n &#62; 70).
1. Device preparations
<ol>
	<li>Plug the device into the USB port of a computer with the ECG software downloaded on it. The measuring device will automatically begin heating up to (37 &#176;C/98.6 &#176;F). The internal heating unit is contained within the measuring unit and heats only the plastic surface. The silver wire electrodes are not heated.</li>
	<li>Allow approximately 15 min for the surface to reach the temperature. Use this time to gather and set up animals. 
	NOTE: The protocol may be paused at this point and the platform can remain plugged in and heating for an extended period of time. In the absence of a self-heating electrode platform, an animal safe heating pad may also be used to keep mother and pups from becoming hypothermic.</li>
</ol>
2. Animal preparations
<ol>
	<li>Collect the mother and pups and keep within the housing cage until ready to collect.</li>
	<li>Once the measuring unit has heated to the temperature, remove the mouse pup from the cage and wipe the thorax with 70% ethanol sprayed on a wipe. Place the pup on the heated surface of the plastic.</li>
	<li>Allow the mouse to acclimate to the surface in the dark for approximately 2-5 minutes.</li>
</ol>
3. Mouse and electrode platform setup (electrode application)
<ol>
	<li>Use a metal spatula, probe, or wooden dowel to collect a small droplet of adhesive, electrical conducting gel (a quick-drying high-conductivity electrode gel commonly used for placement of rodent electrodes). 
	NOTE: Any nonfibrous, solid object can be used to apply the conducting gel, as long as the object will not leave behind synthetic fibers or similar material on the electrodes that could interfere with the quality of the electrical signal.</li>
	<li>Using the spatula/dowel, gently touch the top of each of the four, flattened electrode surfaces by pressing gently down and pulling the conducting gel at an oblique angle away from the center of the electrode construct. Make sure that each individual electrode is completely covered with the gel. 
	CAUTION: This step is extremely important to ensure that the conductive, electrode gel does not adhere to more than a single electrode. Adhesive strands that form between electrodes can conduct charge and potentially interfere with or short out the desired electrical signal. The protocol should not be paused at this time as the gel will begin to solidify and become adherent. Make sure to set up the mouse to the platform within 5-10 minutes of applying conducting gel (or equivalent conductive electrode gel substitution).</li>
	<li>Place the metal spatula or wooden dowel with the remainder of the gel to the side.</li>
	<li>Place the neonatal mouse pup sternum down and prone with the head of the pup facing the outgoing USB edge of the platform. Make sure that a portion of the pup&#8217;s chest is covering each of the four electrodes. Gently restrain the pup&#8217;s forearms by their side while simultaneously holding down for approximately 1 min to allow the conducting gel to set.</li>
	<li>Place rubber silicone bumpers on the right and left sides of the pup. Bumpers should secure the pup on each side and provide stability to prevent excessive movements of the mouse but should NOT prevent all movement of the mouse. Once installed, watch the mouse for a moment and adjust bumper placement as needed. 
	CAUTION: Do not compress the mouse too tightly as this can interfere with respiratory mechanics and respiratory rate.</li>
	<li>Use the dowel that was set aside to apply remaining conducting gel to the grounding tail electrode and place on the rump of the pup. Apply gentle pressure to allow the gel to set before releasing the pup.</li>
	<li>Place the final silicon bumper on top of the rump of the mouse to hold the grounding electrode in place. 
	CAUTION: Do not apply excessive force while placing the final bumper as this could cause discomfort to the pup and/or displace the grounding electrode.</li>
	<li>Grab ahold of the entire platform and gently place inside the Faraday cage. 
	CAUTION: Use caution and ensure the top silicone bumper does not become displaced once the Faraday cage is in place.</li>
	<li>Prior to recording, make sure the mouse pup is not moving excessively and make sure the body and head of the mouse appears secure. 
	CAUTION: Make sure the mouse pup&#8217;s head is able to move somewhat freely within the bumpers and is not completely snout down into the platform. The raised platform is designed to elevate the mouse thorax slightly and prevent suffocation, but this should be closely monitored.</li>
</ol>

<ol>
	<li>Pappano, A. J., Wier, W. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cardiovascular Physiology. 11, 40-41 (2019).</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, 1-19 (2012).</li><li>Sisakian, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiomyopathies:+Evolution+of+pathogenesis+concepts+and+potential+for+new+therapies.">Cardiomyopathies: Evolution of pathogenesis concepts and potential for new therapies.</a> World Journal of Cardiology. 6 (6), 478-494 (2014).</li><li>London, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+Arrhythmias:+From+(Transgenic)+Mice+to+Men.">Cardiac Arrhythmias: From (Transgenic) Mice to Men.</a> Journal of Cardiovascular Electrophysiology. 12 (9), 1089-1091 (2001).</li><li>Zehendner, C. M., Luhmann, H. J., Yang, J. -. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Simple+and+Novel+Method+to+Monitor+Breathing+and+Heart+Rate+in+Awake+and+Urethane+Anesthetized+Newborn+Rodents.">A Simple and Novel Method to Monitor Breathing and Heart Rate in Awake and Urethane Anesthetized Newborn Rodents.</a> PLoS ONE. 5, 62628 (2013).</li><li>Zhao, Y., 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=Dry-contact+microelectrode+membranes+for+wireless+detection+of+electrical+phenotypes+in+neonatal+mouse+hearts.">Dry-contact microelectrode membranes for wireless detection of electrical phenotypes in neonatal mouse hearts.</a> Biomedical Microdevices. 17 (2), 40 (2015).</li><li>Cao, H., 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=Wearable+multi-channel+microelectrode+membranes+for+elucidating+electrophysiological+phenotypes+of+injured+myocardium.">Wearable multi-channel microelectrode membranes for elucidating electrophysiological phenotypes of injured myocardium.</a> Integrative Biology. 6 (8), 789 (2014).</li><li>Ho, D., 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=Heart+rate+and+electrocardiography+monitoring+in+mice.">Heart rate and electrocardiography monitoring in mice.</a> Current Protocols in Mouse Biology. 1 (1), 123-139 (2011).</li><li>Heier, C. R., Hampton, T. G., Wang, D., DiDonato, C. J. <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+electrocardiogram+intervals+during+growth+of+FVB/N+neonate+mice.">Development of electrocardiogram intervals during growth of FVB/N neonate mice.</a> BMC Physiology. 10, 16 (2010).</li><li>Heier, C. R., DiDonato, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ECG+in+neonate+mice+with+spinal+muscular+atrophy+allows+assessment+of+drug+efficacy.">ECG in neonate mice with spinal muscular atrophy allows assessment of drug efficacy.</a> Frontiers Biosciences (Elite Ed). 7, 107-116 (2015).</li><li>Chu, V., 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=Method+for+noninvasively+recording+electrocardiograms+in+conscious+mice.">Method for noninvasively recording electrocardiograms in conscious mice.</a> BMC Physiology. 1, 6 (2001).</li><li>Patel, S. I., Souter, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Equipment-related+electrocardiographic+artifacts:+causes,+characteristics,+consequences,+and+correction.">Equipment-related electrocardiographic artifacts: causes, characteristics, consequences, and correction.</a> Anesthesiology. 108 (1), 138-148 (2008).</li><li>Castellan, R. F. P., Thomson, A., Moran, C. M., Gray, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrocardiogram-gated+kilohertz+visualisation+(EKV)+ultrasound+allows+assessment+of+neonatal+cardiac+structural+and+functional+maturation+and+longitudinal+evaluation+of+regeneration+after+injury.">Electrocardiogram-gated kilohertz visualisation (EKV) ultrasound allows assessment of neonatal cardiac structural and functional maturation and longitudinal evaluation of regeneration after injury.</a> Ultrasound in Medicine and Biology. 46 (1), 167-179 (2020).</li></ol>

The authors report no conflicts of interest.

The data points collected in perinatal day 1 mouse pups are slightly below the average expected values for adult mice (500-700 beats per minute).8 There is an increase in heart rate as the mouse ages, which falls more in line for the expected values (Table 1). However, it is important to emphasize that neonatal values were on the lower end of this range, supporting the idea that normative values should be documented in an age-specific manner. This method is different than other el...

Cardiac function can be measured in different ways, the most common of which includes the use of electrocardiography (ECG) to analyze the conduction of electric current through the heart as well as its overall cardiac cycle and function1. Electrocardiography continues to be a useful diagnostic tool for identifying and characterizing cardiac anomalies in both human and animal models of disease1,2. Irregularities in an electrocardiogram reading can be found in abnormal cardiac development (i.e., congenital heart disease (CHD)), and can include arrhythmias manifesting as changes in heart rate (e.g., bradycardia), and rhythm (e.g., &#8220;heart blocks&#8221;), suggestive of defects in the integrity and/or function of the underlying myocardium. Changes such as these may predispose patients to life-threatening cardiac dysfunction (e.g., congestive heart failure and/or cardiac arrest) and increased mortality3,4. Given the high rates of mortality with severe and untreated CHD, developing a standardized and repeatable method for collecting ECG during this early postnatal period is critical.
Although we are not the first to address this problem, previous methods of collecting ECG on a mouse pups have traditionally included invasive procedures (subcutaneous needle or wire electrodes) and/or the use of anesthetics5,6,7. Advantages of performing noninvasive ECG analysis include minimizing pain and undo stress on the animal. While the experimenter must still be cautious about causing the pup stress, the device is designed to avoid common stressors in order to produce accurate data. In the context of evaluating cardiac function, introducing anesthesia to animals that may have cardiopulmonary abnormalities could potentially mask or even exacerbate underlying conditions. Anesthetics may affect the electrical conduction by altering depolarization and/or repolarization of the cells. Finally, the use of anesthesia can put the newborn pup at an increased risk for hypothermia, which could further confound any inherent pathology. The following protocol does not introduce any anesthetics, invasive procedures, or pronounced discomfort to the pup. Once equipment setup is finalized, device setup and data collection involving the animal can be completed efficiently, after which the pups can be returned to their mother. Additionally, this system allows for repeat and/or serial analyses to be performed, which is ideal for experiments requiring analysis over time, introduction of pharmacological therapies, etc.

<table>
	<tbody>
		<tr>
			<td>LabScribe4</td>
			<td>iWorx</td>
			<td>LabScribe4</td>
			<td>Software used to record ECG</td>
			<td>https://www.iworx.com/users/teaching.php</td>
		</tr>
		<tr>
			<td>Neonatal Mouse ECG &#38; Respiration System</td>
			<td>iWorx</td>
			<td>RS-NMECG : Neonatal Mouse ECG</td>
			<td>ECG device</td>
			<td>https://www.iworx.com/research/cardiac-function/rs-nmecg/</td>
		</tr>
		<tr>
			<td>Tensive Conductive Adhesive Gel</td>
			<td>Parker Laboratories, Inc</td>
			<td>22-60</td>
			<td>Tac-gel used as conductive gel for ECG</td>
			<td>https://www.parkerlabs.com/tensive.asp</td>
		</tr>
	</tbody>
</table>

noninvasive electrocardiography in the perinatal mouse

Electrocardiography (ECG) has long been relied upon as an effective and reliable method of assessing cardiovascular (and cardiopulmonary) function in both human and animal models of disease. Individual heart rate, rhythm, and regularity, combined with quantitative parameters collected from ECG, serve to assess the integrity of the cardiac conduction system as well as the integrated physiology of the cardiac cycle. This article provides a comprehensive description of the methods and techniques used to perform a noninvasive ECG on perinatal and neonatal mouse pups as early as the first postnatal day, without requiring the use of anesthetics. This protocol was designed to directly address a need for a standardized and repeatable method for obtaining ECG in newborn mice. From a translational perspective, this protocol proves to be entirely effective for characterization of congenital cardiopulmonary defects generated using transgenic mouse lines, and particularly for analysis of defects causing lethality at or during the first postnatal days. This protocol also aims to directly address a gap in the scientific literature to characterize and provide normative data associated with maturation of the early postnatal cardiac conduction system. This method is not limited to a specific postnatal timepoint, but rather allows for ECG data collection in neonatal mouse pups from birth to postnatal day 10 (P10), a window that is of critical importance for modeling human diseases in vivo, with particular emphasis on congenital heart disease (CHD).

An ideal ECG would have a clear, prominent signal that allows all waves to be analyzed in several different time frames (Figure 1). The laboratory initially employed a custom application of an electromyography apparatus to produce ECGs of an unsatisfactory quality, which only allowed us to analyze basic parameters such as heart rate (Figure S1). This inspired work with a company to develop a novel prototype ECG device specifically for the analysis of early postnatal mouse pu...

Watch this Scientific Journal Video about Noninvasive Electrocardiography in the Perinatal Mouse at JoVE.com

Noninvasive Electrocardiography in the Perinatal Mouse

Here, we present a noninvasive electrocardiography (ECG) protocol, optimized for early postnatal mice, that does not require the use of anesthetics.

Electrocardiography (ECG) has long been relied upon as an effective and reliable method of assessing cardiovascular (and cardiopulmonary) function in both ...

noninvasive-electrocardiography-in-the-perinatal-mouse

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5.9K Views.  University of Maine, Orono, ME. Here, we present a noninvasive electrocardiography (ECG) protocol, optimized for early postnatal mice, that does not require the use of anesthetics.

Video: Noninvasive Electrocardiography in the Perinatal Mouse

Hyperinsulinemic-euglycemic Clamps in Conscious, Unrestrained Mice

Type 2 diabetes is characterized by a defect in insulin action. The hyperinsulinemic-euglycemic clamp, or insulin clamp, is widely considered the "gold standard" method for assessing insulin action in vivo. During an insulin clamp, hyperinsulinemia is achieved by a constant insulin infusion. Euglycemia is maintained via a concomitant glucose infusion at a variable rate. This variable glucose infusion rate (GIR) is determined by measuring blood glucose at brief intervals throughout the experiment and adjusting the GIR accordingly. The GIR is indicative of whole-body insulin action, as mice with enhanced insulin action require a greater GIR. The insulin clamp can incorporate administration of isotopic 2[14C]deoxyglucose to assess tissue-specific glucose uptake and [3-3H]glucose to assess the ability of insulin to suppress the rate of endogenous glucose appearance (endoRa), a marker of hepatic glucose production, and to stimulate the rate of whole-body glucose disappearance (Rd).
The miniaturization of the insulin clamp for use in genetic mouse models of metabolic disease has led to significant advances in diabetes research. Methods for performing insulin clamps vary between laboratories. It is important to note that the manner in which an insulin clamp is performed can significantly affect the results obtained. We have published a comprehensive assessment of different approaches to performing insulin clamps in conscious mice1 as well as an evaluation of the metabolic response of four commonly used inbred mouse strains using various clamp techniques2. Here we present a protocol for performing insulin clamps on conscious, unrestrained mice developed by the Vanderbilt Mouse Metabolic Phenotyping Center (MMPC; URL: www.mc.vanderbilt.edu/mmpc). This includes a description of the method for implanting catheters used during the insulin clamp. The protocol employed by the Vanderbilt MMPC utilizes a unique two-catheter system3. One catheter is inserted into the jugular vein for infusions. A second catheter is inserted into the carotid artery, which allows for blood sampling without the need to restrain or handle the mouse. This technique provides a significant advantage to the most common method for obtaining blood samples during insulin clamps which is to sample from the severed tip of the tail. Unlike this latter method, sampling from an arterial catheter is not stressful to the mouse1. We also describe methods for using isotopic tracer infusions to assess tissue-specific insulin action. We also provide guidelines for the appropriate presentation of results obtained from insulin clamps.

The hyperinsulinemic-euglycemic clamp, or insulin clamp, is the gold standard for assessing insulin action in vivo. A method for performing insulin clamps in mice is described. This includes a method for arterial catheterization that permits experiments to be performed in conscious, unrestrained mice with minimal stress.

Type 2 diabetes is characterized by a defect in insulin action. The hyperinsulinemic-euglycemic clamp, or insulin clamp, is widely considered the "gold ...

Subretinal Injection of Gene Therapy Vectors and Stem Cells in the Perinatal Mouse Eye

The loss of sight affects approximately 3.4 million people in the United States and is expected to increase in the upcoming years.1 Recently, gene therapy and stem cell transplantations have become key therapeutic tools for treating blindness resulting from retinal degenerative diseases. Several forms of autologous transplantation for age-related macular degeneration (AMD), such as iris pigment epithelial cell transplantation, have generated encouraging results, and human clinical trials have begun for other forms of gene and stem cell therapies.2 These include RPE65 gene replacement therapy in patients with Leber's congenital amaurosis and an RPE cell transplantation using human embryonic stem (ES) cells in Stargardt's disease.3-4 Now that there are gene therapy vectors and stem cells available for treating patients with retinal diseases, it is important to verify these potential therapies in animal models before applying them in human studies. The mouse has become an important scientific model for testing the therapeutic efficacy of gene therapy vectors and stem cell transplantation in the eye.5-8 In this video article, we present a technique to inject gene therapy vectors or stem cells into the subretinal space of the mouse eye while minimizing damage to the surrounding tissue.

This surgical technique illustrates the injection of gene therapy vectors and stem cells into the subretinal space of the mouse eye.

The loss of sight affects approximately 3.4 million people in the United States and is expected to increase in the upcoming years.1 Recently, gene therapy ...

Technical Aspects of the Mouse Aortocaval Fistula

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta and inferior vena cava (IVC) are exposed. The proximal infrarenal aorta and the distal aorta are dissected for clamp placement and needle puncture, respectively. Special attention is paid to avoid dissection between the aorta and the IVC. After clamping the aorta, a 25 G needle is used to puncture both walls of the aorta into the IVC. The surrounding connective tissue is used for hemostatic compression. Successful creation of the AVF will show pulsatile arterial blood flow in the IVC. Further confirmation of successful AVF can be achieved by post-operative Doppler ultrasound.

The goal is to produce an arteriovenous fistula that is simple and reproducible. This method does not use sutures or glue adhesive. Therefore the samples can be used with the least amount of foreign materials for analysis.

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta ...

Noninvasive Intratracheal Intubation to Study the Pathology and Physiology of Mouse Lung

The use of a model that mimics the condition of lung diseases in humans is critical for studying the pathophysiology and/or etiology of a particular disease and for developing therapeutic intervention. With the increasing availability of knockout and transgenic derivatives, together with a vast amount of genetic information, mice provide one of the best models to study the molecular mechanisms underlying the pathology and physiology of lung diseases. Inhalation, intranasal instillation, intratracheal instillation, and intratracheal intubation are the most widely used techniques by a number of investigators to administer materials of interest to mouse lungs. There are pros and cons for each technique depending on the goals of a study. Here a noninvasive intratracheal intubation method that can directly deliver exogenous materials to mouse lungs is presented. This technique was applied to administer bleomycin to mouse lungs as a model to study pulmonary fibrosis.

The use of a model that mimics the condition of lung diseases in humans is critical for studying the pathophysiology and/or etiology of a particular disease and for developing therapeutic intervention. Here a noninvasive intratracheal intubation method that can directly deliver exogenous materials to mouse lungs is presented.

The use of a model that mimics the condition of lung diseases in humans is critical for studying the pathophysiology and/or etiology of a particular ...

In utero Measurement of Heart Rate in Mouse by Noninvasive M-mode Echocardiography

Congenital heart disease (CHD) is the most frequent noninfectious cause of death at birth. The incidence of CHD ranges from 4 to 50/1,000 births (Disease and injury regional estimates, World Health Organization, 2004). Surgeries that often compromise the quality of life are required to correct heart defects, reminding us of the importance of finding the causes of CHD. Mutant mouse models and live imaging technology have become essential tools to study the etiology of this disease. Although advanced methods allow live imaging of abnormal hearts in embryos, the physiological and hemodynamic states of the latter are often compromised due to surgical and/or lengthy procedures. Noninvasive ultrasound imaging, however, can be used without surgically exposing the embryos, thereby maintaining their physiology. Herein, we use simple M-mode ultrasound to assess heart rates of embryos at E18.5 in utero. The detection of abnormal heart rates is indeed a good indicator of dysfunction of the heart and thus constitutes a first step in the identification of developmental defects that may lead to heart failure.

In utero Measurement of Heart Rate in Mouse by Noninvasive M-mode Echocardiography

Ultra-high frequency ultrasound is a powerful live imaging tool to examine cardiac abnormalities in small animals. Its noninvasiveness allows maintaining the physiologic state of embryos. Herein, we show the use of M-mode ultrasound to measure the heart rates of embryos at E18.5 in utero.

Congenital heart disease (CHD) is the most frequent noninfectious cause of death at birth. The incidence of CHD ranges from 4 to 50/1,000 births (Disease ...

Noninvasive Assessment of Cardiac Abnormalities in Experimental Autoimmune Myocarditis by Magnetic Resonance Microscopy Imaging in the Mouse

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-&#945; 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-&#945; 334-352 is shown. EAM and healthy mice were imaged using a 9.4 T (400 MHz) 89 mm vertical core bore scanner equipped with a 4 cm millipede radio-frequency imaging probe and 100 G/cm triple axis gradients. Cardiac images were acquired from anesthetized animals using a gradient-echo-based cine pulse sequence, and the animals were monitored by respiration and pulse oximetry. The analysis revealed an increase in the thickness of the ventricular wall in EAM mice, with a corresponding decrease in the interior diameter of ventricles, when compared with healthy mice. The data suggest that morphological and functional changes in the inflamed hearts can be non-invasively monitored by MRM in live animals. In conclusion, MRM offers an advantage of assessing the progression and regression of myocardial injuries in diseases caused by infectious agents, as well as response to therapies.

This study demonstrates the successful establishment of magnetic resonance microscopy imaging as a non-invasive tool to assess the cardiac abnormalities in mice affected with autoimmune myocarditis. The data indicate that the technique can be used to monitor the disease-progression in live animals.

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events ...

A Piglet Model of Neonatal Hypoxic-Ischemic Encephalopathy

Birth asphyxia, which causes hypoxic-ischemic encephalopathy (HIE), accounts for 0.66 million deaths worldwide each year, about a quarter of the world&#8217;s 2.9 million neonatal deaths. Animal models of HIE have contributed to the understanding of the pathophysiology in HIE, and have highlighted the dynamic process that occur in brain injury due to perinatal asphyxia. Thus, animal studies have suggested a time-window for post-insult treatment strategies. Hypothermia has been tested as a treatment for HIE in pdiglet models and subsequently proven effective in clinical trials. Variations of the model have been applied in the study of adjunctive neuroprotective methods and piglet studies of xenon and melatonin have led to clinical phase I and II trials1,2. The piglet HIE model is further used for neonatal resuscitation- and hemodynamic studies as well as in investigations of cerebral hypoxia on a cellular level. However, it is a technically challenging model and variations in the protocol may result in either too mild or too severe brain injury. In this article, we demonstrate the technical procedures necessary for establishing a stable piglet model of neonatal HIE. First, the newborn piglet (&#60; 24 hr old, median weight 1500 g) is anesthetized, intubated, and monitored in a setup comparable to that found in a neonatal intensive care unit. Global hypoxia-ischemia is induced by lowering the inspiratory oxygen fraction to achieve global hypoxia, ischemia through hypotension and a flat trace amplitude integrated EEG (aEEG) indicative of cerebral hypoxia. Survival is promoted by adjusting oxygenation according to the aEEG response and blood pressure. Brain injury is quantified by histopathology and magnetic resonance imaging after 72 hr.

Hypoxic-ischemic encephalopathy following perinatal asphyxia can be studied using animal models. We demonstrate the procedures necessary for establishing a piglet model of neonatal hypoxic-ischemic encephalopathy.

Birth asphyxia, which causes hypoxic-ischemic encephalopathy (HIE), accounts for 0.66 million deaths worldwide each year, about a quarter of the ...

Confirmation of Myocardial Ischemia and Reperfusion Injury in Mice Using Surface Pad Electrocardiography

Many animal models have been established for the study of myocardial remodeling and heart failure due to its status as the number one cause of mortality worldwide. In humans, a pathologic occlusion forms in a coronary artery and reperfusion of that occluded artery is considered essential to maintain viability of the myocardium at risk. Although essential for myocardial recovery, reperfusion of the ischemic myocardium creates its own tissue injury. The physiologic response and healing of an ischemia/reperfusion injury is different from a chronic occlusion injury. Myocardial ischemia/reperfusion injury is gaining recognition as a clinically relevant model for myocardial infarction studies. For this reason, parallel animal models of ischemia/reperfusion are vital in advancing the knowledge base regarding myocardial injury. Typically, ischemia of the mouse heart after left anterior descending (LAD) coronary artery occlusion is confirmed by visible pallor of the myocardium below the occlusion (ligature). However, this offers only a subjective way of confirming correct or consistent ligature placement, as there are multiple major arteries that could cause pallor in different myocardial regions. A method of recording electrocardiographic changes to assess correct ligature placement and resultant ischemia as well as reperfusion, to supplement observed myocardial pallor, would help yield consistent infarct sizes in mouse models. In turn, this would help decrease the number of mice used. Additionally, electrocardiographic changes can continue to be recorded non-invasively in a time-dependent fashion after the surgery. This article will demonstrate a method of electrocardiographically confirming myocardial ischemia and reperfusion in real time.

During murine myocardial ischemia/reperfusion surgery, correct placement of the occluding ligature is typically confirmed by visible observation of myocardial pallor. Herein, a method of electrocardiographically confirming ischemia and reperfusion, to supplement observed myocardial pallor, is demonstrated in male C57Bl/6 mice.

Many animal models have been established for the study of myocardial remodeling and heart failure due to its status as the number one cause of mortality ...

The Perinatal Asphyxiated Lamb Model: A Model for Newborn Resuscitation

Birth asphyxia accounts for nearly one million deaths worldwide each year, and is one of the primary causes of early neonatal morbidity and mortality. Many aspects of the current neonatal resuscitation guidelines remain controversial given the difficulties in conducting randomized clinical trials owing to the infrequent and often unpredictable need for extensive resuscitation. Most studies on neonatal resuscitation stem from manikin models that fail to truly reflect physiologic changes or piglet models that have cleared their lung fluid and that have completed the transition from fetal to neonatal circulation. The present protocol provides a detailed step-by-step description on how to create a perinatal asphyxiated fetal lamb model. The proposed model has a transitioning circulation and fluid-filled lungs, which mimics human newborns following delivery, and is, therefore, an excellent animal model to study newborn physiology. An important limitation to lamb experiments is the higher associated cost.

Invasive instrumentation of the fetal lamb provides accurate physiologic measurements of the transitioning circulation in a model that closely mimics the newly born infant.

Birth asphyxia accounts for nearly one million deaths worldwide each year, and is one of the primary causes of early neonatal morbidity and mortality. ...

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.

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. ...