Nous remercions le Dr. Helio Salgado, Renata Lataro et Mauro de Oliveira, Faculté de Médecine de Ribeirão Preto, Université de Sao Paulo et le Dr Ben Janssen, Cardiovascular Research Institute Maastricht, Maastricht University, pour son aide généreuse au cours du processus de configuration. Ce travail a été soutenu par FONDECYT subvention N ° 11090114 de la DDC

Protocole a été approuvé par le comité d&#39;éthique de Facultad de Medicina Clinica Alemana Desarrollo-Universidad del. I. Préparation de la perfusion de dobutamine <ol><li> Dissolvez 10 mg de dobutamine dans 20 ml d&#39;eau distillée stérile, afin d&#39;obtenir une solution stock de 500 pg / ml dobutamine. Aliquoter et conserver à -20 ° C. Cette solution peut être utilisée au moins pendant 3 mois. </li><li> Décongeler une aliquote de la solution mère dobutamine à la température ambiante. </li><li> Diluer la solution mère stérile dobutamine dans NaCl à 0,9%, afin d&#39;obtenir la dobutamine solution de travail, dont la concentration est calculée en utilisant la formule: dobutamine (pg / ml) = poids corporel x 0,2. </li><li> Remplir une seringue de 1 ml 29Gx1 / 2 &quot;avec la solution de travail dobutamine. </li><li> Insérez l&#39;aiguille de la seringue dans un 20 cm PE-10 tube. </li><li> Ajuster la seringue dans la pompe à perfusion en suivant les instructions du fabricant. </li><li> Mettre en place la perfusion rampe lors d&#39;une étapeÀ l&#39;étape de format avec une augmentation de 10 pi / min pour chaque étape, pour 6 étapes. </li></ol> II. Préparation du capteur de pression <ol><li> Pour minimiser la dérive du signal, capteur de pression se plonger dans de l&#39;eau stérile à 37 ° C pendant au moins 15 min. Ne pas faire tremper le cathéter de plus de 0,5 cm de profondeur, afin d&#39;éviter que la pression hydrostatique affecte le capteur de pression. </li><li> Électronique calibrer le capteur de pression à 25 et 100 mmHg. Électrique d&#39;entrée (V) est converti en signal de pression (mm de Hg). </li><li> Réglez la fréquence d&#39;échantillonnage de 2 k / s et d&#39;utiliser le filtre passe-bas avec une coupe à 100 Hz. Réglez signal de pression à zéro mmHg. </li><li> Marquer le cathéter 15 mm de la pointe. Lointain à atteindre le coeur du point d&#39;introduction a été estimé par échocardiographie, la détection de la présence de la sonde dans le ventricule gauche. </li></ol> III. Préparation de souris de cathétérisme <ol><li> Poids souris C57BL / 6 mâles, 30-32 semaines d&#39;âge. </li><li> Injecter par voie intrapéritonéale 60 ug / kg de kétamine et de 4 mg / kg de xylazine 1. Remarque: d&#39;autres anesthésiques pourraient être utilisés, par exemple: 350 - 450 mg / kg avertin, 50 ug / kg de pentobarbital ou de 1,5 à 2% 2-3 isoflurane. </li><li> Raser le cou avec un rasoir électrique. </li><li> Placez la souris anesthésiée en position couchée sur une plaque chauffante isotherme chauffée. Sécuriser ses membres un ruban de papier. </li><li> Effectuer un pincement de l&#39;orteil pour confirmer la sédation complète. </li><li> Insérez doucement une sonde rectale pour surveiller la température du corps. En utilisant une sonde vaselinized est recommandé. </li><li> Si la température du corps varie de 37 ° C ± 0,5 ° C, réglez via la plaque chauffante. </li><li> Placez la souris près du museau alimentation en oxygène. </li><li> Placez la région du cou de la souris sous la loupe binoculaire. </li></ol> IV. Acquisition de données <ol><li> Dans le LabChartPro 7 du logiciel, sélectionnez un canal pour l&#39;enregistrement de pression et un canal de la fréquence cardiaque (HR)d&#39;inscription. Dans ce dernier cas, sélectionnez l&#39;option «Mesures cycliques&quot; et la mesure que le taux de configuration. </li><li> Pour le canal de pression définir la plage de l&#39;échelle: 0 à 150 mmHg. </li><li> Pour HR canal réglé plage d&#39;échelle: 200 à 600 bpm. </li><li> Appuyez sur la touche Start pour commencer l&#39;enregistrement. </li><li> Insérez des commentaires indiquant les procédures effectuées, par exemple: l&#39;administration d&#39;anesthésie, le début de la perfusion de dobutamine, la concentration la dobutamine, la respiration changements. </li></ol> V. Cathétérisme cardiaque 4,5 <ol><li> Effectuez une petite incision sur le côté droit près de la mâchoire. Avec des ciseaux séparer le tissu conjonctif de la peau musculaire. </li><li> Effectuer une dissection longitudinale (1,5 - 2 cm) sur le côté droit de la trachée. Séparez le tissu conjonctif, la graisse et le muscle avec des pinces courbes, afin d&#39;exposer l&#39;artère carotide droite près de la trachée. </li><li> Placez une extension dans le côté animal droit d&#39;exposer l&#39;artère carotide. Pulsatilepression générée par le coeur facilite l&#39;identification de l&#39;artère. La veine jugulaire, qui est rouge foncé, est sur la droite. </li><li> Séparer l&#39;artère de tissus adjacents avec une pince courbe. Le nerf vague, qui ressemble à un fil blanc, se trouve le long de l&#39;artère. </li><li> Coupez un morceau de 20 cm de fil 6/0 de soie et &quot;double&quot; il. </li><li> Passez le &quot;double&quot; fil sous l&#39;artère de gauche à droite. Couper le fil, afin d&#39;obtenir des extrémités séparées. </li><li> Passez un troisième fil (10 cm) au-dessous de l&#39;artère. </li><li> Faire un noeud serré dans le filet placé près de la tête, et un lâche dans le fil plus distale. </li><li> Faire un noeud lâche dans la ligne médiane, et fixer l&#39;extrémité droite de la ligne médiane de la garniture de chauffage avec une bande de papier. </li><li> Gardez l&#39;artère carotide humide en laissant tomber stérile à 0,9% de NaCl. Séchez l&#39;excès de liquide avec des cotons-tiges. </li><li> Étirer le fil inférieur avec une pince hémostatique. </li><li> Fixer la position de la pince hémostatique à ciseaux par pinching la peau de l&#39;abdomen, l&#39;étirage du fil supérieur, de manière à obstruer le flux sanguin. Vérifier que le tissu conjonctif autour de l&#39;artère a été éliminée. L&#39;artère doit être pleine de sang et privés de pouls. Empêcher fils de produire une force de couple sur l&#39;artère. </li><li> Faire une section transversale entaille près du fond de l&#39;artère avec une Vannas micro-ciseaux. Gouttes de sang sera versé. </li><li> Insérer le cathéter dans l&#39;artère carotide. Assurez-vous d&#39;introduire le capteur de pression entier. Vérifiez qu&#39;il n&#39;y a aucune perte de sang. </li><li> Sans forcer, ajustez le nœud ligne médiane, afin de maintenir le cathéter en place. Ne pas comprimer trop, le capteur de pression est très fragile. </li><li> Relâchez les ciseaux hémostatiques de l&#39;abdomen animal. </li><li> Tenez la sonde à la main et pousser le fil du milieu, afin d&#39;éviter la perte de sang. Remarque: l&#39;artère doit être plein de sang. </li><li> Début signaux de pression d&#39;enregistrement. </li><li> Lorsque le cathéter est à l&#39;intérieur, l&#39;signal de pression artérielle varie de 60 à 70 à 100-120 mmHg. La forme du signal de pression est indiquée dans la note figure 1.A: si vous êtes intéressé à, à cet instant, vous pouvez enregistrer la pression artérielle si le signal est stable pendant au moins 5 min. Valeurs de FC ont été obtenus à partir des formes d&#39;onde de pression compte tenu d&#39;un intervalle de 30 secondes de signal d&#39;enregistrement. Il est possible d&#39;utiliser également une méthode ECG pour la mesure directe des ressources humaines, selon les objectifs de l&#39;enquête. </li><li> Poussez doucement le cathéter en place pour observer un changement dans la forme du signal de pression (figure 1.B). Une fois le cathéter à l&#39;intérieur du ventricule gauche, le signal de pression fluctue de 0 à 100-120 mmHg. S&#39;il est difficile de faire glisser le cathéter, pincer la poitrine des animaux avec deux doigts. </li><li> Contrôler en permanence le rythme respiratoire, la température corporelle, le niveau de l&#39;anesthésie et le signal de pression. Tous devraient rester stables. </li></ol> VI. La perfusion de dobutamine <ol><li&gt; Pour canulation de la veine jugulaire n&#39;oubliez pas de décoller le tissu adipeux autour de la veine, afin d&#39;éviter sa perforation. La procédure chirurgicale pour occlusion de la veine est similaire à la procédure indiquée pour l&#39;artère carotide. </li><li> Introduire un tube PE-10 dans la veine. Assurez-vous que la circulation sanguine n&#39;est pas bloqué déplaçant vers l&#39;arrière le piston de la seringue. </li><li> Perfusion de dobutamine commence avec 10 pi / min et terminer par 60 pi / min. A chaque étape, le débit de perfusion est maintenue pendant 2 min 6. </li><li> Après la dernière dose de dobutamine, euthanasier l&#39;animal avec une surdose d&#39;anesthésie. </li></ol> VII. Analyse des données <ol><li> Pour l&#39;analyse de données, choisissez la section des données enregistrées de votre intérêt. Soyez sûr de considérer un intervalle de temps où le signal de pression est stable. </li><li> Sélectionnez l&#39;icône Setup dans le module la pression artérielle. Indiquer le type sélectionné du signal de pression. </li><li> Automatiquement les écrans LabChartPro logiciel 7, moyenne, maximumet les valeurs minimales en matière de RH, de la pression systolique (P max), la pression diastolique (P min), en fin de diastole (PDE), le développement maximal de pression positive (dP / dt max) et le développement maximal de pression négative (dP / dt min). En outre, les paramètres cardiaques peuvent être représentées sur le tracé de pression. </li></ol>

<ol>
	<li>Hart, C. Y., Burnett, J. C., Redfield, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+avertin+versus+xylazine-ketamine+anesthesia+on+cardiac+function+in+normal+mice.">Effects of avertin versus xylazine-ketamine anesthesia on cardiac function in normal mice.</a> Am. J. Physiol. Heart Circ. Physiol. 281, H1938-H1945 (2001).</li><li>Janssen, B. J., 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=Effects+of+anesthetics+on+systemic+hemodynamics+in+mice.">Effects of anesthetics on systemic hemodynamics in mice.</a> Am. J. Physiol. Heart Circ. Physiol. 287, H1618-H1624 (2004).</li><li>Lorenz, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+practical+guide+to+evaluating+cardiovascular,+renal,+and+pulmonary+function+in+mice.">A practical guide to evaluating cardiovascular, renal, and pulmonary function in mice.</a> Am. J. Physiol. Regul. Integr. Comp. Physiol. 282, R1565-R1582 (2002).</li><li>Lorenz, J. N., Robbins, J. <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+intraventricular+pressure+and+cardiac+performance+in+the+intact+closed-chest+anesthetized+mouse.">Measurement of intraventricular pressure and cardiac performance in the intact closed-chest anesthetized mouse.</a> Am. J. Physiol. 272, H1137-H1146 (1997).</li><li>Nemoto, S., DeFreitas, G., Carabello, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+catheterization+technique+in+a+closed-chest+murine+model.">Cardiac catheterization technique in a closed-chest murine model.</a> Contemp. Top. Lab Anim. Sci. 42, 34-38 (2003).</li><li>Daniels, A., 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=Impaired+cardiac+functional+reserve+in+type+2+diabetic+db/db+mice+is+associated+with+metabolic,+but+not+structural,+remodelling.">Impaired cardiac functional reserve in type 2 diabetic db/db mice is associated with metabolic, but not structural, remodelling.</a> Acta Physiol. (Oxf). 200, 11-22 (2010).</li><li>De Celle, T., 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=Long-term+structural+and+functional+consequences+of+cardiac+ischaemia-reperfusion+injury+in+vivo+in+mice.">Long-term structural and functional consequences of cardiac ischaemia-reperfusion injury in vivo in mice.</a> Exp. Physiol. 89, 605-615 (2004).</li><li>Huntgeburth, M., 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=Transforming+growth+factor+beta+oppositely+regulates+the+hypertrophic+and+contractile+response+to+beta-adrenergic+stimulation+in+the+heart.">Transforming growth factor beta oppositely regulates the hypertrophic and contractile response to beta-adrenergic stimulation in the heart.</a> PLoS One. 6, e26628 (2011).</li><li>Reddy, A. K., 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=Cardiac+function+in+young+and+old+Little+mice.">Cardiac function in young and old Little mice.</a> J. Gerontol. A. Biol. Sci. Med. Sci. 62, 1319-1325 (2007).</li><li>Christoffersen, C., 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=Cardiac+lipid+accumulation+associated+with+diastolic+dysfunction+in+obese+mice.">Cardiac lipid accumulation associated with diastolic dysfunction in obese mice.</a> Endocrinology. 144, 3483-3490 (2003).</li></ol>

Aucun conflit d&#39;intérêt déclaré.

Test de stress cardiaque induite par la dobutamine et surveillés par cathétérisme cardiaque est laborieuse. Néanmoins, en suivant le protocole décrit ici et avec un peu de temps de formation, il est possible d&#39;évaluer six paramètres hémodynamiques en une seule expérience qui durent environ une heure. Les étapes critiques du protocole présenté ici sont les canules des vaisseaux sanguins. En ce qui concerne la canulation de l&#39;artère carotide, l&#39;incision effectuée doit...

<table border="1"><tbody><tr><td></td><td></td><td></td><td> Réactifs </td></tr><tr><td> PE-50/10 </td><td> Warner Instruments </td><td> 64-0752 </td><td></td></tr><tr><td> Fil de soie 6/0 HR17 </td><td> Tagum </td><td> SN0713K </td><td></td></tr><tr><td> Xylacin 20 mg / ml </td><td> Centrovet Laboratorio </td><td></td><td></td></tr><tr><td> Kétamine 100 mg / ml </td><td> Drag Pharma </td><td></td><td></td></tr><tr><td> Chlorure de sodium à 0,9% </td><td> Lab SA Sanderson </td><td></td><td></td></tr><tr><td> Chlorhydrate de dobutamine </td><td> Sigma-Aldrich </td><td> D0676 </td><td></td></tr><tr><td> Seringue à insuline U-100 29G x ½ &quot; </td><td> Terumo Medical Co. </td><td></td><td></td></tr><tr><td> Pince à dissection Micro Style cm 11,5 7 </td><td> LawtonMedizintechnik </td><td> 09-0959 </td><td></td></tr><tr><td> Graefe Forceps MCV 0,7 mm 7cm </td><td> Lawton Medizintechnik </td><td> 62-0263 </td><td></td></tr><tr><td> Colliers de Dieffenbach bulldog Cl Str 38 mm </td><td> Lawton Medizintechnik </td><td> 60-010 </td><td></td></tr><tr><td> Ciseaux Vannas 8 Str cm Fh </td><td> Lawton Medizintechnik </td><td> 63-1400 </td><td></td></tr><tr><td></td><td></td><td></td><td> Équipement </td></tr><tr><td> SPR-671 cathéter Mikro-Tip pression </td><td> Millar instruments </td><td> 840-6719 </td><td></td></tr><tr><td> PCU-2000 Unité de contrôle de pression </td><td> Millar instruments </td><td> 880-0129 </td><td></td></tr><tr><td> PowerLab 4/30 </td><td> ADInstruments Pty Ltd </td><td> ML866 </td><td></td></tr><tr><td> LabChartPro 7 </td><td> ADInstruments Pty Ltd </td><td> MLU260 / 7 </td><td></td></tr><tr><td> Legato200 Pompe à perfusion </td><td> KdScientific </td><td> KD-KDS210P </td><td></td></tr><tr><td> Régulateur de température TCAT-2LV et plaque chauffante isotherme </td><td> Physitemp instruments Inc </td><td></td><td></td></tr><tr><td> Fourniture d&#39;oxygène médical </td><td> Indura </td><td></td><td></td></tr><tr><td> Sonde rectale </td><td> ADInstruments Pty Ltd </td><td> MLT1404 </td><td></td></tr><tr><td> Microscope trinoculaire, éclairage axial </td><td> LW Scientific </td><td> Z2B-TRI-ETNE, ILP-1502-LTS1, ILP-1502-DGGF </td><td></td></tr></tbody></table>

cardiac stress test induced by dobutamine and monitored by cardiac catheterization in mice

La dobutamine est un agoniste β-adrénergique avec une plus grande affinité pour le récepteur exprimé dans le cœur (β 1) que pour les récepteurs exprimés dans les artères (β 2). Lorsque administré par voie systémique, il augmente la demande cardiaque. Ainsi, la dobutamine démasque rythme anormal ou zones ischémiques potentiellement le risque d&#39;infarctus. Surveillance de la fonction cardiaque pendant un test d&#39;effort cardiaque peut être effectuée par l&#39;une ou ecocardiography cathétérisme cardiaque. Cette dernière est une technique invasive mais plus précis et informatif que le premier. Test de stress cardiaque induite par la dobutamine et surveillés par cathétérisme cardiaque réalisé comme décrit ici permet, en une seule expérience, la mesure des paramètres hémodynamiques suivants: fréquence cardiaque (FC), la pression systolique, la pression diastolique, la pression télédiastolique, maximale pression positive développement (dP / dt max) et maximale négatifs dans la presseure développement (dP / dt min), à des conditions de base et sous des doses croissantes de dobutamine. Comme on s&#39;y attendait, chez des souris normales, nous avons observé une dobutamine liée à la dose augmentation de la FC, dP / dt max et dP / dt min. En outre, à la plus forte dose testée (12 ng / g / min), la décompensation cardiaque de haute teneur en graisses régime alimentaire induits par les souris obèses a été démasqué.

Le signal de pression artérielle est définie par la pression systolique et la pression diastolique. Lorsque le capteur de pression est à l&#39;intérieur du ventricule gauche, la pression (LVP) de forme d&#39;onde est caractérisée par une chute à zéro de la pression diastolique et l&#39;apparition de la contraction de l&#39;oreillette gauche, avant la contraction du ventricule (Figure 1). A l&#39;état initial, la kétamine-xylazine anesthésiés souris normales ont HR de 280 ± 24, P max</s...

Watch this Scientific Journal Video about Cardiac Stress Test Induced by Dobutamine and Monitored by Cardiac Catheterization in Mice at JoVE.com

Cardiac Stress Test Induced by Dobutamine and Monitored by Cardiac Catheterization in Mice

Nous décrivons le protocole pour effectuer un test de stress cardiaque induite par la dobutamine et surveillés par cathétérisme cardiaque chez les souris normales. En outre, nous montrons son application à démasquer la maladie cardiaque infraclinique en haute teneur en graisses régime alimentaire induits par les souris obèses.

Test de stress cardiaque induite par la dobutamine et surveillé par cathétérisme cardiaque chez la souris

Dobutamine is a &beta;-adrenergic agonist with an affinity higher for receptor expressed in the heart (&beta;1) than for receptors expressed in the ...

cardiac-stress-test-induced-dobutamine-monitored-cardiac

Research

JoVE Journal

Medicine

17.9K vues.  Clínica Alemana Universidad del Desarrollo. Nous décrivons le protocole pour effectuer un test de stress cardiaque induite par la dobutamine et surveillés par cathétérisme cardiaque chez les souris normales. En outre, nous montrons son application à démasquer la maladie cardiaque infraclinique en haute teneur en graisses régime alimentaire induits par les souris obèses.

Vidéo: Cardiac Stress Test Induced by Dobutamine and Monitored by Cardiac Catheterization in Mice

Assessment of Right Ventricular Structure and Function in Mouse Model of Pulmonary Artery Constriction by Transthoracic Echocardiography

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, the RV is significantly affected in pulmonary diseases such as pulmonary artery hypertension (PAH). In addition, the RV is remarkably sensitive to cardiac pathologies, including left ventricular (LV) dysfunction, valvular disease or RV infarction4. To understand the role of RV in the pathogenesis of cardiac diseases, a reliable and noninvasive method to access the RV structurally and functionally is essential.
A noninvasive trans-thoracic echocardiography (TTE) based methodology was established and validated for monitoring dynamic changes in RV structure and function in adult mice. To impose RV stress, we employed a surgical model of pulmonary artery constriction (PAC) and measured the RV response over a 7-day period using a high-frequency ultrasound microimaging system. Sham operated mice were used as controls. Images were acquired in lightly anesthetized mice at baseline (before surgery), day 0 (immediately post-surgery), day 3, and day 7 (post-surgery). Data was analyzed offline using software.
Several acoustic windows (B, M, and Color Doppler modes), which can be consistently obtained in mice, allowed for reliable and reproducible measurement of RV structure (including RV wall thickness, end-diastolic&#160;and end-systolic dimensions), and function (fractional area change, fractional shortening, PA peak velocity, and peak pressure gradient) in normal mice and following PAC.
Using this method, the pressure-gradient resulting from PAC was accurately measured in real-time using Color Doppler mode and was comparable to direct pressure measurements performed with a Millar high-fidelity microtip catheter. Taken together, these data demonstrate that RV measurements obtained from various complimentary views using echocardiography are reliable, reproducible and can provide insights regarding RV structure and function. This method will enable a better understanding of the role of RV cardiac dysfunction.

Right ventricle (RV) dysfunction is critical to the pathogenesis of cardiovascular disease, yet limited methodologies are available for its evaluation. Recent advances in ultrasound imaging provide a noninvasive and accurate option for longitudinal RV study. Herein, we detail a step-by-step echocardiographic method using a murine model of RV pressure overload.

Évaluation de ventriculaire droite Structure et fonction dans le modèle de souris de l&#39;artère pulmonaire constriction par échocardiographie transthoracique

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, ...

Recherche

Médecine

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.

Évaluation non invasive de la Cardiac Malformations en auto-immune expérimentale myocardite par résonance magnétique microscopie imagerie chez la souris

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

Early Detection of Drug-Induced Renal Hemodynamic Dysfunction Using Sonographic Technology in Rats

The kidney normally functions to maintain hemodynamic homeostasis and is a major site of damage caused by drug toxicity. Drug-induced nephrotoxicity is estimated to contribute to 19- 25% of all clinical cases of acute kidney injury (AKI) in critically ill patients. AKI detection has historically relied on metrics such as serum creatinine (sCr) or blood urea nitrogen (BUN) which are demonstrably inadequate in full assessment of nephrotoxicity in the early phase of renal dysfunction. Currently, there is no robust diagnostic method to accurately detect hemodynamic alteration in the early phase of AKI while such alterations might actually precede the rise in serum biomarker levels. Such early detection can help clinicians make an accurate diagnosis and help in in decision making for therapeutic strategy. Rats were treated with Cisplatin to induce AKI. Nephrotoxicity was assessed for six days using high-frequency sonography, sCr measurement and upon histopathology of kidney. Hemodynamic evaluation using 2D and Color-Doppler images were used to serially study nephrotoxicity in rats, using the sonography. Our data showed successful drug-induced kidney injury in adult rats by histological examination. Color-Doppler based sonographic assessment of AKI indicated that resistive-index (RI) and pulsatile-index (PI) were increased in the treatment group; and peak-systolic velocity (mm/s), end-diastolic velocity (mm/s) and velocity-time integral (VTI, mm) were decreased in renal arteries in the same group. Importantly, these hemodynamic changes evaluated by sonography preceded the rise of sCr levels. Sonography-based indices such as RI or PI can thus be useful predictive markers of declining renal function in rodents. From our sonography-based observations in the kidneys of rats that underwent AKI, we showed that these noninvasive hemodynamic measurements may consider as an accurate, sensitive and robust method in detecting early stage kidney dysfunction. This study also underscores the importance of ethical issues associated with animal use in research.

Early stage hemodynamic dysfunction is critical to the development of kidney disease. Yet, detection methodologies are limited. Recent advances in sonography provide a noninvasive, accurate option for early detection of kidney injury. This study outlines a step-by-step, sonographic methodology for detecting kidney dysfunction using a drug-induced nephrotoxicity rat model.

Détection précoce du médicament-Induced rénale hémodynamique Dysfonction Utilisation de échographique Technology chez le rat

The kidney normally functions to maintain hemodynamic homeostasis and is a major site of damage caused by drug toxicity. Drug-induced nephrotoxicity is ...

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

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

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

Cathétérisme cardiaque chez la souris pour mesurer le volume de pression Relation: Étudier les effets Bowditch

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

Myocardial Infarction in Neonatal Mice, A Model of Cardiac Regeneration

Myocardial infarction induced by coronary artery ligation has been used in many animal models as a tool to study the mechanisms of cardiac repair and regeneration, and to define new targets for therapeutics. For decades, models of complete heart regeneration existed in amphibians and fish, but a mammalian counterpart was not available. The recent discovery of a postnatal window during which mice possess regenerative capabilities has led to the establishment of a mammalian model of cardiac regeneration. A surgical model of mammalian cardiac regeneration in the neonatal mouse is presented herein. Briefly, postnatal day 1 (P1) mice are anesthetized by isoflurane and placed on an ice pad to induce hypothermia. After the chest is opened, and the left anterior descending coronary artery (LAD) is visualized, a suture is placed around the LAD to inflict myocardial ischemia in the left ventricle. The surgical procedure takes 10-15 min. Visualizing the coronary artery is crucial for accurate suture placement and reproducibility. Myocardial infarction and cardiac dysfunction are confirmed by triphenyl-tetrazolium chloride (TTC) staining and echocardiography, respectively. Complete regeneration 21 days post myocardial infarction is verified by histology. This protocol can be used to as a tool to elucidate mechanisms of mammalian cardiac regeneration after myocardial infarction.

This protocol describes a highly reproducible model of cardiac regeneration by surgical induction of myocardial infarction in the left ventricle of postnatal day 1 mice. The method involves induction of hypothermic anesthesia and ligation of the left anterior descending coronary artery.

Infarctus du myocarde chez les souris néonatales, Un modèle de régénération cardiaque

Myocardial infarction induced by coronary artery ligation has been used in many animal models as a tool to study the mechanisms of cardiac repair and ...

A Model of Glaucoma Induced by Circumlimbal Suture in Rats and Mice

The circumlimbal suture is a technique for inducing experimental glaucoma in rodents by chronically elevating intraocular pressure (IOP), a well-known risk factor for glaucoma. This protocol demonstrates a step-by-step guide on this technique in Long Evans rats and C57BL/6 mice. Under general anesthesia, a "purse-string" suture is applied on the conjunctiva, around the equator and behind the limbus of the eye. The fellow eye serves as an untreated control. Over the duration of our study, which was a period of 8 weeks for rats and 12 weeks for mice, IOP remained elevated, as measured regularly by rebound tonometry in conscious animals without topical anesthesia. In both species, the sutured eyes showed electroretinogram features consistent with preferential inner retinal dysfunction. Optical coherence tomography showed selective thinning of the retinal nerve fiber layer. Histology of the rat retina in cross-section found reduced cell density in the ganglion cell layer, but no change in other cellular layers. Staining of flat-mounted mouse retinae with a ganglion cell specific marker (RBPMS) confirmed ganglion cell loss. The circumlimbal suture is a simple, minimally invasive and cost-effective way to induce ocular hypertension that leads to ganglion cell injury in both rats and mice.

Chronic ocular hypertension is induced by applying a circumlimbal suture in rats and mice, leading to functional and structural deterioration of the retinal ganglion cells consistent with glaucoma.

Un modèle de glaucome induit par la Suture Circumlimbal chez le rat et la souris

The circumlimbal suture is a technique for inducing experimental glaucoma in rodents by chronically elevating intraocular pressure (IOP), a well-known ...

Isolation of Atrial Myocytes from Adult Mice

The electrophysiological properties of atrial myocytes importantly affect overall cardiac function. Alterations in the underlying ionic currents responsible for the action potential can cause pro-arrhythmic substrates that underlie arrhythmias, such as atrial fibrillation, which are highly prevalent in many conditions and disease states. Isolating adult mouse atrial cardiomyocytes for use in patch-clamp experiments has greatly advanced our knowledge and understanding of the cellular electrophysiology in the healthy atrial myocardium and in the setting of atrial pathophysiology. In addition, studies using genetic mouse models have elucidated the role of a vast array of proteins in regulating atrial electrophysiology. Here we provide a detailed protocol for the isolation of cardiomyocytes from the atrial appendages of adult mice using a combination of enzymatic digestion and mechanical dissociation of these tissues. This approach consistently and reliably yields isolated atrial cardiomyocytes that can then be used to characterize cellular electrophysiology by measuring action potentials and ionic currents in patch-clamp experiments under a number of experimental conditions.

This protocol is used to isolate single atrial cardiomyocytes from the adult mouse heart using a chunk digestion approach. This approach is used to isolate right or left atrial myocytes that can be used to characterize atrial myocyte electrophysiology in patch-clamp studies.

Isolement des myocytes auriculaires des souris adultes

The electrophysiological properties of atrial myocytes importantly affect overall cardiac function. Alterations in the underlying ionic currents ...

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) generated by recording both pressure and volume during cardiac catheterization are vital when assessing both systolic and diastolic cardiac function. Left and right heart function are closely related, reflected in ventricular interdependence. Thus, recording biventricular function in the same animal is important to get a complete assessment of cardiac function. In this protocol, a closed chest approach to cardiac catheterization consistent with the way catheterization is performed in patients is adopted in mice. While challenging, the closed chest strategy is a more physiological approach, because opening the chest results in major changes in preload and afterload that create artifacts, most notably a fall in systemic blood pressure. While high-resolution echocardiography is used to assess rodents, cardiac catheterization is invaluable, particularly when assessing diastolic pressures in both ventricles.
Described here is a procedure to perform invasive, closed chest, sequential left and right ventricular pressure-volume (PV) loops in the same animal. PV loops are acquired using&#160;admittance technology with a mouse pressure-volume catheter and pressure-volume system acquisition. The procedure is described, beginning with the neck dissection, which is required to access the right jugular vein and the right carotid artery, to the insertion and positioning of the catheter, and finally the data acquisition. Then, the criteria required to ensure the acquisition of high-quality PV loops are discussed. Finally, the analysis of the left and right ventricular PV loops and the different hemodynamic parameters available to quantify systolic and diastolic ventricular function are briefly described.

Presented here is a protocol to assess biventricular heart function in mice by generating pressure-volume (PV) loops from the right and left ventricle in the same animal using closed chest catheterization. The focus is on the technical aspect of surgery and data acquisition.

Évaluation biventriculaire de la fonction cardiaque et des boucles pression-volume par cathétérisme thoracique fermé chez la souris

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) ...

Cardiac Response to &#946;-Adrenergic Stimulation Determined by Pressure-Volume Loop Analysis

Determination of the cardiac function is a robust endpoint analysis in animal models of cardiovascular diseases in order to characterize effects of specific treatments on the heart. Due to the feasibility of genetic manipulations the mouse has become the most common mammalian animal model to study cardiac function and to search for new potential therapeutic targets. Here we describe a protocol to determine cardiac function&#160;in vivo using pressure-volume loop measurements and analysis during basal conditions and under &#946;-adrenergic stimulation by intravenous infusion of increasing concentrations of isoproterenol. We provide a refined protocol including ventilation support taking into account the positive end-expiratory pressure to ameliorate negative effects during open-chest measurements, and potent analgesia (Buprenorphine) to avoid uncontrollable myocardial stress evoked by pain during the procedure. All together the detailed description of the procedure and discussion about possible pitfalls enables highly standardized and reproducible pressure-volume loop analysis, reducing the exclusion of animals from the experimental cohort by preventing possible methodological bias.

Cardiac Response to &amp;#946;-Adrenergic Stimulation Determined by Pressure-Volume Loop Analysis

Here we describe a cardiac pressure-volume loop analysis under increasing doses of intravenously infused isoproterenol to determine the intrinsic cardiac function and the &#946;-adrenergic reserve in mice. We use a modified open-chest approach for the pressure-volume loop measurements, in which we include ventilation with positive end-expiratory pressure.

Réponse cardiaque à la stimulation β-adrénergique déterminée par l’analyse de la boucle pression-volume

Determination of the cardiac function is a robust endpoint analysis in animal models of cardiovascular diseases in order to characterize effects of ...

A Large Animal Model for Acute Kidney Injury by Temporary Bilateral Renal Artery Occlusion

Acute kidney injury (AKI) is associated with higher risk for morbidity and mortality post-operatively. Ischemia-reperfusion injury (IRI) is the most common cause of AKI. To mimic this clinical scenario, this study presents a highly reproducible large animal model of renal IRI in swine using temporary percutaneous bilateral balloon-catheter occlusion of the renal arteries. The renal arteries are occluded for 60 min by introducing the balloon-catheters through the femoral and carotid artery and advancing them into the proximal portion of the arteries. Iodinated contrast is injected in the aorta to assess any opacification of the kidney vessels and confirm the success of the artery occlusion. This is furtherly confirmed by the flattening of the pulse waveform at the tip of the balloon catheters. The balloons are deflated and removed after 60 min of bilateral renal artery occlusion, and the animals are allowed to recover for 24 h. At the end of the study, plasma creatinine and blood urea nitrogen significantly increase, while eGFR and urine output significantly decrease. The need for iodinated contrast is minimal and does not affect renal function. Bilateral renal artery occlusion better mimics the clinical scenario of perioperative renal hypoperfusion, and the percutaneous approach minimizes the impact of the inflammatory response and the risk of infection seen with an open approach, such as a laparotomy. The ability to create and reproduce this clinically relevant swine model eases the clinical translation to humans.

This study presents a highly reproducible large animal model of renal ischemia-reperfusion injury in swine using temporary percutaneous bilateral balloon-catheter occlusion of the renal arteries for 60 min and reperfusion for 24 h.

Un grand modèle animal pour les lésions rénales aiguës par occlusion bilatérale temporaire de l’artère rénale

Acute kidney injury (AKI) is associated with higher risk for morbidity and mortality post-operatively. Ischemia-reperfusion injury (IRI) is the most ...