Agradecemos ao Dr. Hélio Salgado, Renata Lataro e Mauro de Oliveira, da Escola de Medicina de Ribeirão Preto da Universidade de São Paulo e Ben Dr. Janssen, Instituto de Pesquisa Cardiovascular de Maastricht, Universidade de Maastricht, por generosa assistência durante o processo de configuração. Este trabalho foi financiado por subvenções Fondecyt N ° 11090114 para SDC

Protocolo foi aprovado pelo Comitê de Ética da Faculdade de Medicina Clínica Alemã-Universidade del Desarrollo. I. Preparação infusão de dobutamina <ol><li> Dissolvem-se 10 mg de dobutamina, em 20 ml de água destilada estéril, com o fim de se obter uma solução stock de 500 ug / ml de dobutamina. Alíquota e armazenar a -20 ° C. Esta solução pode ser utilizada, pelo menos, durante 3 meses. </li><li> Descongelar uma alíquota da solução de reserva de dobutamina, à temperatura ambiente. </li><li> Diluir solução-mãe de dobutamina em NaCl estéril 0,9%, a fim de obter a solução de trabalho de dobutamina, cuja concentração é calculada utilizando a fórmula: dobutamina (ug / ml) = peso corporal x 0,2. </li><li> Encha uma seringa 1 ml 29Gx1 / 2 &quot;com solução de trabalho dobutamina. </li><li> Inserir a agulha da seringa para um tubo de 20 centímetros PE-10. </li><li> Ajuste a seringa na bomba de infusão, seguindo as instruções do fabricante. </li><li> Defina-se a infusão de rampa em uma etapa-A-passo com o formato de um aumento de 10 ul / min para cada etapa, de 6 passos. </li></ol> II. Preparando sensor de pressão <ol><li> Para minimizar a variação do sinal, o sensor de pressão submergir em água estéril a 37 ° C durante pelo menos 15 min. Não molhe o cateter mais de 0,5 cm de profundidade, de modo a evitar que a pressão hidrostática atinge o sensor de pressão. </li><li> Electronicamente calibrar o sensor de pressão a 25 e 100 mmHg. Eléctrico de entrada (Volt) é convertido em sinal de pressão (mmHg). </li><li> Definir a taxa de amostragem de 2 k / s e utilizar o filtro passa baixo com um corte de 100 Hz. Definir o sinal de pressão para zero mmHg. </li><li> Marcar o cateter 15 mm da ponta. Distante para alcançar o coração a partir do ponto de introdução foi estimada por ecocardiograma, detectando a presença do cateter no interior do ventrículo esquerdo. </li></ol> III. Preparando Rato para cateterismo <ol><li> Peso C57BL / 6, machos, 30-32 semanas de idade. </li><li> Injectar por via intraperitoneal de cetamina 60 mg / kg e 4 mg / kg de xilazina 1. Nota: Outros anestésicos podem ser utilizados, por exemplo: 350-450 ug / kg avertina, 50 ug / kg de pentobarbital, ou 1,5-2% 2-3 isoflurano. </li><li> Raspar o pescoço com um barbeador elétrico. </li><li> Posicione o mouse anestesiado em decúbito dorsal em uma placa de aquecimento aquecido isotérmica. Fixe seus membros com fita de papel. </li><li> Realizar uma pitada de igual para confirmar sedação completa. </li><li> Insira com cuidado a sonda retal para monitorar a temperatura do corpo. Usando sonda vaselinized é recomendada. </li><li> Se a temperatura do corpo difere de 37 ° C ± 0,5 ° C, ajusta-lo através da placa de aquecimento. </li><li> Coloque focinho de rato perto do suprimento de oxigênio. </li><li> Coloque a região do pescoço do rato, ao microscópio estereoscópico. </li></ol> IV. Aquisição de Dados <ol><li> Na 7 LabChartPro software, selecione um canal para registro de pressão e um canal para a freqüência cardíaca (FC)registro. Para este último, selecione a opção &quot;Medidas cíclicos&quot; e medição de configuração como taxa. </li><li> Para o canal de pressão definir a faixa de escala: 0 a 150 mmHg. </li><li> Para HR canal definir a faixa de escala: 200-600 bpm. </li><li> Pressione a tecla START para iniciar o registro. </li><li> Inserir comentários indicando procedimentos realizados, por exemplo: administração de anestesia, o início da infusão de dobutamina, a concentração de dobutamina, respirando alterações. </li></ol> V. Cateterismo Cardíaco 4,5 <ol><li> Realizar uma pequena incisão no lado direito, perto da mandíbula. Com uma tesoura separar o tecido conjuntivo da pele-muscular. </li><li> Realizar uma dissecção longitudinal (1,5-2 cm), no lado direito da traqueia. Separou-se a gordura do tecido conjuntivo, músculo e com fórceps curvo, de modo a expor a artéria carótida direita perto da traqueia. </li><li> Coloque um expansor no lado animal direito para expor a artéria carótida. Pulsátilpressão gerada pelo coração facilita a identificação da artéria. A veia jugular, que é vermelho escuro, está à direita. </li><li> Separou-se a artéria a partir de tecidos adjacentes com fórceps curvo. O nervo vago, que se assemelha a uma linha branca, fica ao longo da artéria. </li><li> Corte um pedaço de 20 cm de fio 6/0 e seda &quot;double-lo&quot;. </li><li> Passe a linha &quot;casal&quot; sob a artéria da esquerda para a direita. Cortar o fio, a fim de obter extremidades separadas. </li><li> Passar por um terceiro segmento (10 cm) abaixo da artéria. </li><li> Dê um nó apertado no fio posicionado perto da cabeça, e um solto no segmento mais distal. </li><li> Dê um nó frouxo na linha do meio, e fixar a extremidade direita da linha média para a almofada de aquecimento com uma fita de papel. </li><li> Mantenha artéria carótida úmido, largando estéril NaCl 0,9%. Secar o excesso de líquido com cotonetes. </li><li> Estique a linha inferior com uma pinça hemostática. </li><li> Fixar a posição da tesoura pinça hemostática por pavançando a pele do abdómen, que se estende a linha de cima, a fim de ocluir o fluxo de sangue. Verificar que o tecido conjuntivo em torno da artéria foi removido. A artéria deve estar cheio de sangue e privados de pulso. Prevenir tópicos de produzir uma força de binário sobre a artéria. </li><li> Fazer uma secção transversal nick perto da parte inferior da artéria com um Vannas micro-tesoura. Gotas de sangue será derramado. </li><li> Inserir o cateter na artéria carótida. Certifique-se de introduzir o sensor de pressão inteiro. Verificar que não há perda de sangue. </li><li> Suavemente ajustar o nó rosca do meio, a fim de segurar o cateter no lugar. Não comprimir em demasia, o sensor de pressão é muito frágil. </li><li> Solte a tesoura hemostat do abdômen animal. </li><li> Segurar o cateter com uma mão e empurra o fio do meio, a fim de evitar a perda de sangue. Nota: artéria deve estar cheio de sangue. </li><li> Iniciar sinais de pressão de gravação. </li><li> Quando o cateter está dentro, osinal de pressão arterial oscila 60-70 a 100-120 mmHg. A forma do sinal de pressão é mostrada na Figura 1.A. Nota: se estiver interessado em diante, neste ponto do tempo é possível registar a pressão arterial se sinal é estável durante pelo menos 5 min. Valores de FC foram obtidos a partir das formas de onda de pressão, considerando um intervalo de 30 segundos de sinal de gravação. É possível utilizar também um método de ECG para a medição directa da AR, de acordo com os objectivos de investigação. </li><li> Suavemente empurrar o cateter se observar uma alteração na forma do sinal de pressão (Figura 1 B). Uma vez que o cateter está no interior do ventrículo esquerdo, o sinal de pressão varia de 0 a 100-120 mmHg. Se for difícil para deslizar o cateter, belisque peito animal com dois dedos. </li><li> Continuamente controlar a taxa de respiração, a temperatura corporal, o nível de anestesia e sinal de pressão. Todos eles devem permanecer estáveis. </li></ol> VI. A infusão de dobutamina <ol><li&gt; Para a canulação da veia jugular certifique-se de descascar o tecido adiposo em torno da veia, a fim de evitar a sua perfuração. O procedimento cirúrgico para a oclusão da veia é semelhante ao procedimento descrito para a artéria carótida. </li><li> Introduzir um tubo de PE-10 para dentro da veia. Confirmar que o fluxo de sangue não é bloqueado se movendo para trás o êmbolo da seringa. </li><li> A infusão de dobutamina começa com 10 ul / min e terminar com 60 ul / min. Em cada passo, a velocidade de perfusão é mantida durante 2 min 6. </li><li> Após a última dose de dobutamina, sacrificar o animal com uma overdose de anestesia. </li></ol> VII. Análise de Dados <ol><li> Para análise dos dados, escolha a seção dos dados gravados de seu interesse. Certifique-se de considerar um intervalo de tempo em que o sinal de pressão é estável. </li><li> Selecione o ícone de configuração no módulo de Pressão Arterial. Indique o tipo selecionado de sinal de pressão. </li><li> Automaticamente os LabChartPro 7 software exibe média máxima,e os valores mínimos de RH, pressão arterial sistólica (P max), pressão diastólica (P min), pressão diastólica final (PDE), o desenvolvimento positivo pressão máxima (dP / dtmax) e desenvolvimento de pressão negativa máxima (dP / dt min). Além disso, os parâmetros cardíacos podem ser representadas no traçado da pressão. </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>

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Teste de estresse cardíaco induzido por dobutamina e monitorado por cateterismo cardíaco é trabalhoso. No entanto, seguindo o protocolo aqui descrever e com um curto tempo de formação, é possível avaliar a seis parâmetros hemodinâmicos numa única experiência que duram aproximadamente uma hora. Os passos essenciais do protocolo aqui apresentado são as cânulas dos vasos sanguíneos. Em relação à canulação da artéria carótida, a incisão realizada deve ser profundo o suficie...

<table border="1"><tbody><tr><td></td><td></td><td></td><td> Reagentes </td></tr><tr><td> PE-50/10 </td><td> Warner Instruments </td><td> 64-0752 </td><td></td></tr><tr><td> Fio de seda 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> Cetamina 100 mg / ml </td><td> Arraste Pharma </td><td></td><td></td></tr><tr><td> Cloreto de sódio a 0,9% </td><td> Laboratório de Sanderson SA </td><td></td><td></td></tr><tr><td> Cloridrato de Dobutamina </td><td> Sigma-Aldrich </td><td> D0676 </td><td></td></tr><tr><td> Seringa de insulina U-100 29G x ½ &quot; </td><td> Terumo Medical Co. </td><td></td><td></td></tr><tr><td> Fórceps Dissecando Estilo Micro centímetros 11,5 7 </td><td> LawtonMedizintechnik </td><td> 09-0959 </td><td></td></tr><tr><td> Graefe Fórceps DCV 0,7 milímetros 7 centímetros </td><td> Lawton Medizintechnik </td><td> 62-0263 </td><td></td></tr><tr><td> Grampos Dieffenbach bulldog Str Cl 38 milímetros </td><td> Lawton Medizintechnik </td><td> 60-010 </td><td></td></tr><tr><td> Vannas Tesoura 8 centímetros Str Fh </td><td> Lawton Medizintechnik </td><td> 63-1400 </td><td></td></tr><tr><td></td><td></td><td></td><td> Equipamento </td></tr><tr><td> SPR-671 Pressão cateter Mikro-Tip </td><td> Millar instrumentos </td><td> 840-6719 </td><td></td></tr><tr><td> PCU-2000 Unidade de Controle de Pressão </td><td> Millar instrumentos </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> Bomba de infusão Legato200 </td><td> KdScientific </td><td> KD-KDS210P </td><td></td></tr><tr><td> TCAT-2LV controlador de temperatura e placa de aquecimento isotérmico </td><td> PhysiTemp instrumentos Inc. </td><td></td><td></td></tr><tr><td> Fornecimento de oxigênio medicinal </td><td> Indura </td><td></td><td></td></tr><tr><td> Retal sonda </td><td> ADInstruments Pty Ltd. </td><td> MLT1404 </td><td></td></tr><tr><td> Microscópio trinocular, iluminação axial </td><td> LW Científico </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

A dobutamina é um agonista β-adrenérgico com uma afinidade mais elevada para o receptor expresso no coração (β 1) do que para os receptores expressos nas artérias (β 2). Quando administrada sistemicamente, aumenta a procura cardíaca. Assim, dobutamina desmascara ritmo anormal ou áreas isquêmicas potencialmente em risco de infarto. A monitorização da função cardíaca durante um teste de esforço cardíaco pode ser realizada por qualquer ecocardiografia ou a cateterização cardíaca. A última é uma técnica invasiva, mas mais preciso e informativo que a primeira. Teste de esforço cardíaco induzido pela dobutamina e monitorizada por cateterismo realizado como descrito aqui permite, numa única experiência, a medição dos seguintes parâmetros hemodinâmicos: ritmo cardíaco (HR), pressão sistólica, pressão diastólica, a pressão diastólica final, a pressão positiva máxima desenvolvimento (dP / dtmax) e negativa da imprensa máximaure desenvolvimento (dP / dt min), em condições basais e sob doses crescentes de dobutamina. Como esperado, em camundongos normais foi observado um aumento relacionado com a dose de dobutamina em RH, dP / dt max e dP / dt min. Além disso, na maior dose testada (12 ng / g / min), a descompensação cardíaca de alto teor de gordura da dieta, os ratos obesos induzidos foi desmascarado.

O sinal de pressão arterial é definida pela pressão sistólica e diastólica. Quando o sensor de pressão está no interior do ventrículo esquerdo, a sua pressão (LVP) da forma de onda é caracterizada por uma queda para zero da pressão diastólica, e o aparecimento da contracção do átrio esquerdo, antes de contracção do ventrículo esquerdo (Figura 1). No estado inicial, cetamina-xilazina anestesiados ratos normais tiveram de RH de 280 ± 24, P máximo de 107 ± 8, P min</sub...

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

Nós descrever o protocolo para realizar um teste de estresse cardíaco induzido por dobutamina e monitorado por cateterismo cardíaco em ratos normais. Também vamos mostrar a sua aplicação para desmascarar doença cardíaca subclínica em alto teor de gordura da dieta induzida ratos obesos.

Teste de estresse cardíaco induzido por dobutamina e Monitorado por cateterismo cardíaco em ratos

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

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Medicine

17.9K visualizações.  Clínica Alemana Universidad del Desarrollo. Nós descrever o protocolo para realizar um teste de estresse cardíaco induzido por dobutamina e monitorado por cateterismo cardíaco em ratos normais. Também vamos mostrar a sua aplicação para desmascarar doença cardíaca subclínica em alto teor de gordura da dieta induzida ratos obesos.

Vídeo: 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.

Avaliação da Estrutura e Função do Ventrículo Direito em modelo de camundongo Pulmonary Artery constrição por Ecocardiografia transtorácica

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

Medicina

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.

Avaliação não invasiva da Cardiac Anormalidades em Experimental Auto-imune Miocardite por Ressonância Magnética Microscopia de imagem no Rato

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.

Detecção precoce de Induzida por Medicamentos Renal hemodinâmica Disfunção Usando ultrassonografia Tecnologia em Ratos

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.

O cateterismo cardíaco em camundongos para medir o volume Pressão do relacionamento: Investigando o efeito 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.

Infarto do miocárdio em ratos neonatais, um modelo de regeneração cardíaca

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.

Um modelo de Glaucoma induzido por sutura Circumlimbal em ratos e camundongos

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.

Isolamento de miócitos atriais de camundongos adultos

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.

Avaliação Biventricular da Função Cardíaca e Alças Pressão-Volume por Cateterismo Fechado de Tórax em Camundongos

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.

Resposta cardíaca à estimulação β-adrenérgica determinada pela análise do loop de pressão-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.

Um grande modelo animal para lesão renal aguda por oclusão bilateral temporária da artéria renal

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