Os autores agradecem Christiane Pahrmann por sua assistência técnica e histologia do espectáculo.

<html> Balb / C camundongos com peso mínimo de 20g em uma idade de 8 a 12 semanas são comprados de Charles River (Sandhofer Weg 7, D-97633 Sulzfeld). Os ratos são alojados em condições convencionais, pellets rato alimentado padrão e água ad libitum. Anestesiar mouse com isoflurano (2%) utilizando uma câmara de indução. <ol><li> Raspar a área do pescoço e do lado esquerdo da caixa torácica e desinfectar com álcool 80%. </li><li> Posicione o mouse sobre as suas costas e colocar uma máscara sobre seu nariz e boca para manter a anestesia. </li><li> Verificar os reflexos beliscar a cauda e patas traseiras para ter a certeza que o rato é suficiente anestesiado. </li><li> Sob visão microscópica realizar uma incisão mediana cervical separando o músculo, pele e tecido que cobre a traquéia. </li><li> Quando a traquéia é exposta cortar um pequeno furo no tecido entre dois anéis de cartucho abaixo da glote para inserir o tubo endotraqueal (Figura 1). Inserir o tubo endotraqueal segurando a parte cranial da traquéia usando micro forecepts cirúrgico. Verifique o movimento do tórax, para ter certeza de que ambos os pulmões são bem ventiladas. </li><li> A taxa de respiração (RR) deve ser aproximadamente 110 por minuto, com pressão inspiratória de 17 a 18 centímetros H 2 O. Vire o mouse com cuidado, deitado sobre seu lado direito, de frente para o lado esquerdo. Realizar uma toracotomia leftsided entre as 3 ª e 4 ª costela, e dissecar o tecido muscular e com cuidado, usando um Cauter para prevenir hemorragias. </li><li> Abra o tórax com cuidado, uma vez que o tórax é aberto, encontrar o coração, sem tocar o pulmão com qualquer objeto cortante. Agora, remova a parte do saco pericárdico, que está cobrindo o coração. </li><li> A LAD está localizado entre a artéria pulmonar ea aurícula esquerda. Use uma sutura Prolene 8-0 (Ethicon, Norderstedt, Alemanha) para ligadura do LAD proximal com uma sutura simples (Figura 2). </li><li> Colocar um tubo no peito (cateter, 28G venal), entre a 4 ª ea 5 ª costela. </li><li> Feche a incisão torácica em camadas, usando 6-0 Prolene sutura (Ethicon, Norderstedt, Alemanha) para se adaptar as costelas e prolene 4-0 (Ethicon, Norderstedt, Alemanha) para fechar a pele. </li><li> Drenagem do tórax com a ajuda de uma seringa de 2ml com cuidado (Figura 3). Posicione o mouse sobre as suas costas. Agora pegue o tubo endotraqueal e adaptar os anéis da traquéia cartucho com um ponto único usando suturas 7-0 Prolene (Ethicon, Norderstedt, Alemanha). </li><li> Coloque a máscara sobre o mouse e fechar a pele usando suturas Prolene 4-0 (Ethicon, Norderstedt, Alemanha). </li></ol> Validação Existem diferentes possibilidades para confirmar o sucesso da LAD ligadura. O teste de troponina pode ser realizada 6 a 18 horas após a cirurgia, usando apenas 150 l de sangue sem a necessidade de eutanásia do animal. O sangue é aplicado a um kit personalizado troponina teste (TROP T Sensitive, Roche, Mannheim) (Figura 4). Troponina é uma proteína reguladora nos filamentos de actina da célula muscular, existem diferentes isotipos nos três tipos de músculos. A cTnI e cTnT isotipos são encontrados no coração e são liberados em lesão tecidual. O teste padronizado para a troponina T (cTnT) é baseada em duas coração anticorpos monoclonais específicos, um armadilhas da troponina na amostra de sangue, o segundo é um marcador. A área de infarto podem ser identificados macroscopicamente após 3 dias (Figura 5). TTC (2,3,5-trifeniltetrazólio cloreto) coloração viabilidade tecidual medidas utilizadas para avaliar o tamanho do infarto. Corante azul de Evans (1,5%, 1,0 mL) em tampão fosfato (PBS) é injetado na cavidade do ventrículo esquerdo para medir a área do miocárdio isquêmico. O rato é sacrificados eo coração é colhida e seccionados em fatias. As fatias de tecido são incubados em 1% de solução PBS TTC, pH 7,4 a 37 ° C por 20min. Tecidos são fixados em 10% PBS-formol tamponado durante a noite a 2-8 ° C. TTC é administrado ex vivo para corante azul de Evans-negativos áreas (Figura 6). Para histologia o mouse tem que ser sacrificados eo coração tem de ser incorporado para processamento posterior. Depois de realizar cortes em parafina, as lâminas são coradas com H &amp; E (hematoxilina e eosina) ou tricrômico de visualizar tecido fibrótico (Figura 7). <img src="/files/ftp_upload/1438/1438fig1.jpg" alt="Figura 1" /> Figura 1: tubo traqueal. 1A: Exposed traquéia, após incisão cervical ventral. 1B: Traquéia é aberto dois anéis de cartilagem caudal à laringe. 1C: tubo traqueal é inserido na traquéia. <img src="/files/ftp_upload/1438/1438fig2.jpg" alt="Figura 2" /> Figura 2: O coração é exposto através de uma toracotomia esquerda lados, o LAD é ligada. t &quot;&gt; <img src="/files/ftp_upload/1438/1438fig3.jpg" alt="Figura 3" /> Figura 3: Depois que o tórax é fechado, um dreno pleura é executada. O mouse ainda está sob anestesia. <img src="/files/ftp_upload/1438/1438fig4.jpg" alt="Figura 4" /> Figura 4: Duas linhas aparecem após alguns minutos, quando o teste de troponina é positivo. <img src="/files/ftp_upload/1438/1438fig5.jpg" alt="Figura 5" /> Figura 5: Mostra o coração explantado. 5A: Aspecto macroscópico do coração com a área isquêmica com uma cor desbotada esbranquiçada. 5B: seção transversal do coração infartado, a área isquêmica mostra no canto superior direito.

<ol>
	<li>Atkins, B. Z., Hueman, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+cardiomyoplasty+improves+diastolic+properties+of+injured+Heart.">Cellular cardiomyoplasty improves diastolic properties of injured Heart.</a> J Surg Res. 85 (2), 234-242 (1999).</li><li>Jaquet, K., KT, K. r. a. u. s. e. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+myocardial+scar+size+after+implantation+of+mesenchymal+stem+cells+in+rats:+what+is+the+mechanism.">Reduction of myocardial scar size after implantation of mesenchymal stem cells in rats: what is the mechanism.</a> Stem Cells Dev. 14 (3), 299-309 (2005).</li><li>Joung, B., Kim, I. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone+marrow+mononuclear+stem+cells+transplanted+in+rat+infarct+myocardium+improved+the+electrical+conduction+without+evidence+of+proarrhythmic+effects.">Bone marrow mononuclear stem cells transplanted in rat infarct myocardium improved the electrical conduction without evidence of proarrhythmic effects.</a> Yonsei Med J. 48 (5), 754-764 (2007).</li></ol>

Financiamento O presente estudo teve o apoio do Hospital Universitário Hamburg (MK, Mulher Habilitação Grant), DFG (SS, SCHR992/3-1), ISHLT (TD, Research Award 2009). Afirmação Todos os animais receberam cuidados humanos, em conformidade com os Princípios de Laboratório Animal Care, experimentos em animais foram realizados de acordo com as diretrizes e regulamentos estabelecidos pela Sociedade Nacional de Pesquisa Médica e do Manual sobre Cuidados e Uso de Animais de Laboratório, publicado pela National Institutes of Health (Institutos Nacionais de Saúde publicação 85-23, revisado em 1985). Todos os animais foram obtidos a partir de Charles River Laboratories (Sulzfeld, Alemanha) e foram mantidos no biotério atendimento do Hospital Universitário Hamburg Eppendorf. Os animais receberam ração padrão e água ad libitum.

Em resumo, este vídeo visualiza o modelo LAD ligadura passo-a-passo e identifica LAD-ligadura em ratos com a mesma facilidade viável procedimentos cirúrgicos.

lad-ligation: a murine model of myocardial infarction

Modelos de pesquisa de infarto e isquemia miocárdica são essenciais para investigar os processos agudos e crônicos Pathobiological e fisiopatológicas da isquemia miocárdica e para desenvolver e otimizar o tratamento futuro. Dois métodos diferentes de criar isquemia do miocárdio são realizadas em roedores de laboratório. O primeiro método é criar crio infarto, uma técnica rápida, mas impreciso, onde um crio-caneta é aplicado sobre a superfície do coração (1-3). Usando este método, o cientista não pode garantir que o crio cicatriz leva a isquemia, também uma lesão do miocárdio é vasta criado que mostra efeitos colaterais fisiopatológicos que não estão relacionados ao infarto do miocárdio. O segundo método é a ligadura permanente da artéria descendente anterior esquerda (DAE). Aqui, o LAD é ligada com um ponto único, formando uma isquemia, que pode ser visto quase que imediatamente. Fechando a LAD, há ainda fluxo de sangue é permitida naquela área, enquanto o tecido circundante do miocárdio não é quase afetados. Este procedimento cirúrgico imita os aspectos Pathobiological e fisiopatológicas que ocorrem na isquemia-infarto do miocárdio relacionados. O método introduzido neste vídeo demonstra o procedimento cirúrgico de um modelo de infarto do rato por ligadura do LAD. Este modelo é conveniente para estudos Pathobiological e fisiopatológicos, bem como imunobiológicos em infarto cardíaco. A técnica mostrada proporciona alta precisão e se correlaciona bem com cortes histológicos.

Watch this Scientific Journal Video about LAD-Ligation: A Murine Model of Myocardial Infarction at JoVE.com

LAD-Ligation: A Murine Model of Myocardial Infarction

Este vídeo demonstra como usar um modelo rápido e confiável para o estudo de processos Pathobiological e fisiopatológicas da isquemia miocárdica.

LAD Ligadura: Um Modelo murino de Infarto do Miocárdio

Research models of infarction and myocardial ischemia are essential to investigate the acute and chronic pathobiological and pathophysiological processes ...

lad-ligation-a-murine-model-of-myocardial-infarction

Research

JoVE Journal

Biology

44.4K visualizações.  University Heart Center Hamburg. Este vídeo demonstra como usar um modelo rápido e confiável para o estudo de processos Pathobiological e fisiopatológicas da isquemia miocárdica.

Vídeo: LAD-Ligation: A Murine Model of Myocardial Infarction

Murine Pancreatic Islet Isolation

Isolamento Islet murino de pâncreas

Biologia

Murine Model of Hindlimb Ischemia 

In the United States, peripheral arterial disease (PAD) affects about 10 million individuals, and is also prevalent worldwide. Medical therapies for symptomatic relief are limited. Surgical or endovascular interventions are useful for some individuals, but long-term results are often disappointing. As a result, there is a need for developing new therapies to treat PAD. The murine hindlimb ischemia preparation is a model of PAD, and is useful for testing new therapies. When compared to other models of tissue ischemia such as coronary or cerebral artery ligation, femoral artery ligation provides for a simpler model of ischemic tissue. Other advantages of this model are the ease of access to the femoral artery and low mortality rate. 
In this video, we demonstrate the methodology for the murine model of unilateral hindimb ischemia. The specific materials and procedures for creating and evaluating the model will be described, including the assessment of limb perfusion by laser Doppler imaging. This protocol can also be utilized for the transplantation and non-invasive tracking of cells, which is demonstrated by Huang et al.1.

Murine Model of Hindlimb Ischemia

The surgical procedure for induction of unilateral hindlimb ischemia is demonstrated, with confirmation of ischemia by laser Doppler perfusion imaging.

Modelo murino de isquemia dos membros posteriores

In the United States, peripheral arterial disease (PAD) affects about 10 million individuals, and is also prevalent worldwide.  Medical therapies for ...

Murine Renal Transplantation Procedure

Renal orthotopic transplantation in mice is a technically challenging procedure. Although the first kidney transplants in mice were performed by Russell et al over 30 years ago (1) and refined by Zhang et al years later (2), few people in the world have mastered this procedure. In our laboratory we have successfully performed 1200 orthotopic kidney transplantations with &gt; 90% survival rate. The key points for success include stringent control of reperfusion injury, bleeding and thrombosis, both during the procedure and post-transplantation, and use of 10-0 instead of 11-0 suture for anastomoses.
Post-operative care and treatment of the recipient is extremely important to transplant success and evaluation. All renal graft recipients receive antibiotics in the form of an injection of penicillin immediately post-transplant and sulfatrim in the drinking water continually. Overall animal health is evaluated daily and whole blood creatinine analyses are performed routinely with a portable I-STAT machine to assess graft function.

Renal transplantation in mice is a technically challenging procedure that requires careful post-operative care and treatment for success.

Murino Procedimento de Transplante Renal

Renal orthotopic transplantation in mice is a technically challenging procedure. Although the first kidney transplants in mice were performed by Russell ...

Rodent Working Heart Model for the Study of Myocardial Performance and Oxygen Consumption

Isolated working heart models have been used to understand the effects of loading conditions, heart rate and medications on myocardial performance in ways that cannot be accomplished in vivo. For example, inotropic medications commonly also affect preload and afterload, precluding load-independent assessments of their myocardial effects in vivo. Additionally, this model allows for sampling of coronary sinus effluent without contamination from systemic venous return, permitting assessment of myocardial oxygen consumption. Further, the advent of miniaturized pressure-volume catheters has allowed for the precise quantification of markers of both systolic and diastolic performance. We describe a model in which the left ventricle can be studied while performing both volume and pressure work under controlled conditions. 
In this technique, the heart and lungs of a Sprague-Dawley rat (weight 300-500 g) are removed en bloc under general anesthesia. The aorta is dissected free and cannulated for retrograde perfusion with oxygenated Krebs buffer. The pulmonary arteries and veins are ligated and the lungs removed from the preparation. The left atrium is then incised and cannulated using a separate venous cannula, attached to a preload block. Once this is determined to be leak-free, the left heart is loaded and retrograde perfusion stopped, creating the working heart model. The pulmonary artery is incised and cannulated for collection of coronary effluent and determination of myocardial oxygen consumption. A pressure-volume catheter is placed into the left ventricle either retrograde or through apical puncture. If desired, atrial pacing wires can be placed for more precise control of heart rate. This model allows for precise control of preload (using a left atrial pressure block), afterload (using an afterload block), heart rate (using pacing wires) and oxygen tension (using oxygen mixtures within the perfusate).

Isolated working heart models can be used to measure the effect of loading conditions, heart rate, and medications on myocardial performance and oxygen consumption. We describe methods for preparation of a rodent left heart working model that permits study of systolic and diastolic performance and oxygen consumption under various conditions.

Roedor Trabalho Modelo do coração para o estudo do desempenho do miocárdio eo consumo de oxigênio

Isolated working heart models have been used to understand the effects of loading conditions, heart rate and medications on myocardial performance in ways ...

The Murine Choline-Deficient, Ethionine-Supplemented (CDE) Diet Model of Chronic Liver Injury

Chronic liver diseases, such as viral hepatitis, alcoholic liver disease, or non-alcoholic fatty liver disease, are characterized by continual inflammation, progressive destruction and regeneration of the hepatic parenchyma, liver progenitor cell proliferation, and fibrosis. The end-stage of every chronic liver disease is cirrhosis, a major risk factor for the development of hepatocellular carcinoma. To study processes regulating disease initiation, establishment, and progression, several animal models are used in laboratories. Here we describe a six-week time course of the choline-deficient and ethionine-supplemented (CDE) mouse model, which involves feeding six-week old male C57BL/6J mice with choline-deficient chow and 0.15% DL-ethionine-supplemented drinking water. Monitoring of animal health and a typical body weight loss curve are explained. The protocol demonstrates the gross examination of a CDE-treated liver and blood collection by cardiac puncture for subsequent serum analyses. Next, the liver perfusion technique and collection of different hepatic lobes for standard evaluations are shown, including liver histology assessments by hematoxylin and eosin or Sirius Red stainings, immunofluorescent detection of hepatic cell populations as well as transcriptome profiling of the liver microenvironment. This mouse model is suitable for studying inflammatory, fibrogenic, and liver progenitor cell dynamics induced through chronic liver disease and can be used to test potential therapeutic agents that may modulate these processes.

The Murine Choline-Deficient, Ethionine-Supplemented CDE Diet Model of Chronic Liver Injury

Here we describe a common method to induce chronic liver injury in mice by feeding of a choline-deficient and ethionine-supplemented (CDE) diet. We demonstrate health monitoring, liver perfusion, isolation, and preservation. A time course of six weeks can inform about liver injury, pathohistology, fibrosis, inflammatory, and liver progenitor cell responses.

O murino colina deficiente, Ethionine-completada (CDE) dieta modelo de lesão hepática crônica

Chronic liver diseases, such as viral hepatitis, alcoholic liver disease, or non-alcoholic fatty liver disease, are characterized by continual ...

A Murine Model of Vertical Sleeve Gastrectomy

Bariatric surgery, such as vertical sleeve gastrectomy (VSG), is a surgery of the gastrointestinal tract that is performed for the purpose of weight loss. Bariatric surgery is currently the most effective long-term treatment for obesity. In addition to weight loss, bariatric surgery produces additional health benefits such as remission of type 2 diabetes, remission of hypertension, and decreased risk of developing certain types of cancer. The mechanisms beyond weight loss for these benefits remain incompletely defined. Therefore, animal models of bariatric surgery are being developed and validated to identify the mechanisms leading to these benefits, with the goal of improving understanding of gastrointestinal physiology and identifying new therapeutic targets. VSG has become the most commonly performed bariatric procedure in the clinic in the United States because it is highly effective at producing weight loss and metabolic improvement, and is simpler to perform than other bariatric procedures. Therefore, we have developed and validated a murine model of VSG. This murine VSG model recapitulates many of the effects of VSG seen in humans, including improved glucose and blood pressure regulation. The method is based on isolation of the stomach, ligation of gastric vessels, and removal of 70% of the stomach by transecting along the greater curvature of the stomach. We have successfully applied this surgical protocol to various genetically modified mouse lines to define the mechanistic contributors to the benefits of VSG. Furthermore, this murine VSG model has been combined with other surgical techniques, to achieve deeper mechanistic insight. Therefore, this is a simple and versatile model for studying gastrointestinal physiology and the health benefits of bariatric surgery.

The following describes the performance of vertical sleeve gastrectomy in mice. This is a type of weight-loss surgery that involves removal of approximately 70% of the stomach.

Um modelo murino de gastrectomia de manga Vertical

Bariatric surgery, such as vertical sleeve gastrectomy (VSG), is a surgery of the gastrointestinal tract that is performed for the purpose of weight loss. ...

Mass Spectrometry Analysis to Identify Ubiquitylation of EYFP-tagged CENP-A (EYFP-CENP-A)

Studying the structure and the dynamics of kinetochores and centromeres is important in understanding chromosomal instability (CIN) and cancer progression. How the chromosomal location and function of a centromere (i.e., centromere identity) are determined and participate in accurate chromosome segregation is a fundamental question. CENP-A is proposed to be the non-DNA indicator (epigenetic mark) of centromere identity, and CENP-A ubiquitylation is required for CENP-A deposition at the centromere, inherited through dimerization between cell division, and indispensable to cell viability.
Here we describe mass spectrometry analysis to identify ubiquitylation of EYFP-CENP-A K124R mutant suggesting that ubiquitylation at a different lysine is induced because of the EYFP tagging in the CENP-A K124R mutant protein. Lysine 306 (K306) ubiquitylation in EYFP-CENP-A K124R was successfully identified, which corresponds to lysine 56 (K56) in CENP-A through mass spectrometry analysis. A caveat is discussed in the use of GFP/EYFP or the tagging of high molecular weight protein as a tool to analyze the function of a protein. Current technical limit is also discussed for the detection of ubiquitylated bands, identification of site-specific ubiquitylation(s), and visualization of ubiquitylation in living cells or a specific single cell during the whole cell cycle.
The method of mass spectrometry analysis presented here can be applied to human CENP-A protein with different tags and other centromere-kinetochore proteins. These combinatory methods consisting of several assays/analyses could be recommended for researchers who are interested in identifying functional roles of ubiquitylation.

Mass Spectrometry Analysis to Identify Ubiquitylation of EYFP-tagged CENP-A EYFP-CENP-A

CENP-A ubiquitylation is an important requirement for CENP-A deposition at the centromere, inherited through dimerization between cell division, and indispensable to cell viability. Here we describe mass spectrometry analysis to identify ubiquitylation of EYFP-tagged CENP-A (EYFP-CENP-A) protein.

Análise de espectrometria de massa para identificar a ubiquização do CENP-A marcado pelo EYFP (EYFP-CENP-A)

Studying the structure and the dynamics of kinetochores and centromeres is important in understanding chromosomal instability (CIN) and cancer ...

A Murine Model of a Burn Wound Reconstructed with an Allogeneic Skin Graft

Trivial superficial wounds heal without complications by primary intention. Deep wounds, such as full thickness burns, heal by secondary intention and require surgical debridement and skin grafting. Successful integration of the donor graft into a recipient wound bed depends on timely recruitment of immune cells, robust angiogenic response and new extracellular matrix formation. The development of novel therapeutic agents, which target some key processes involved in wound healing, are hindered by the lack of reliable preclinical models with optimized objective assessment of wound closure. Here, we describe an inexpensive and reproducible model of experimental full thickness burn wound reconstructed with an allogeneic skin graft. The wound is induced on the dorsum surface of anaesthetized inbred wild type mice from the BALB/C and SKH1-Hrhr backgrounds. The burn is produced using a brass template measuring 10 mm in diameter, which is preheated to 80 &#176;C and delivered at a constant pressure for 20 s. Burn eschar is excised 24 hours after the injury and replaced with a full thickness graft harvested from the tail of a genetically similar donor mouse. No specialized equipment is required for the procedure and surgical techniques are straightforward to follow. The method may be effortlessly implemented and reproduced in most research settings. Certain limitations are associated with the model. Due to technical difficulties, the harvest of thinner split thickness skin grafts is not possible. The surgical method we describe here allows for the reconstruction of burn wounds using full thickness skin grafts. It may be used to carry out preclinical therapeutic testing.

The aim of this study was to develop a murine model of burn wound healing. A thermal burn was induced on the dorsal skin of mice using a preheated brass template. Burned tissue was debrided and overlaid with a skin graft harvested from the tail of a genetically similar donor mouse.

Um modelo murino de uma ferida de queimadura reconstruída com um enxerto de pele aogenética

Trivial superficial wounds heal without complications by primary intention. Deep wounds, such as full thickness burns, heal by secondary intention and ...

The Establishment of a Murine Mandibular Molar Extraction Socket Healing Model

This study introduces the development of a molar extraction model in the murine mandible to provide a practicable model for studying alveolar bone regeneration and intramembranous ossification. C57/J6 mice were used to extract the mandibular first molar to establish this model. They were euthanized, and the bilateral mandibles harvested, at 1 week and 4 weeks post-surgery, respectively. Subsequent serial stereoscopic harvest, histological assessment, and immunofluorescence staining were performed to demonstrate successful surgery. Immediately after surgery, the stereoscopic images displayed an empty extraction socket. The hematoxylin and eosin (H&#38;E) at 1 week and Masson staining at 4 weeks post-surgery showed that the area of the original root was partially and fully filled with bone trabeculae, respectively. The immunofluorescence staining showed that, compared with the homeostasis side, the Sp7 expression increased at 1 week post-surgery, suggesting vigorous osteogenesis in the alveolar fossa. All these results demonstrated a practicable murine tooth extraction socket healing model. Upcoming studies revealing the mechanisms of jawbone defect healing or socket healing could adopt this method.

This protocol demonstrates step-by-step details of how to extract the mandibular first molar in the mouse. It provides an alternative method for researchers focusing on jawbone healing and regeneration.

O Estabelecimento de um Modelo de Cicatrização de Molares Mandibulares Murinos

This study introduces the development of a molar extraction model in the murine mandible to provide a practicable model for studying alveolar bone ...

Explorando o desempenho cardíaco dependente de FC usando um protocolo de estimulação atrial

A Pacing-Controlled Procedure for the Assessment of Heart Rate-Dependent Diastolic Functions in Murine Heart Failure Models

Heart failure with preserved ejection fraction (HFpEF) is a condition characterized by diastolic dysfunction and exercise intolerance. While exercise-stressed hemodynamic tests or MRI can be used to detect diastolic dysfunction and diagnose HFpEF in humans, such modalities are limited in basic research using mouse models. A treadmill exercise test is commonly used for this purpose in mice, but its results can be influenced by body weight, skeletal muscle strength, and mental state. Here, we describe an atrial-pacing protocol to detect heart rate (HR)-dependent changes in diastolic performance and validate its usefulness in a mouse model of HFpEF. The method involves anesthetizing, intubating, and performing pressure-volume (PV) loop analysis concomitant with atrial pacing. In this work, a conductance catheter was inserted via a left ventricular apical approach, and an atrial pacing catheter was placed in the esophagus. Baseline PV loops were collected before the HR was slowed with ivabradine. PV loops were collected and analyzed at HR increments ranging from 400 bpm to 700 bpm via atrial pacing. Using this protocol, we clearly demonstrated HR-dependent diastolic impairment in a metabolically induced HFpEF model. Both the relaxation time constant (Tau) and the end-diastolic pressure-volume relationship (EDPVR) worsened as the HR increased compared to control mice. In conclusion, this atrial pacing-controlled protocol is useful for detecting HR-dependent cardiac dysfunctions. It provides a new way to study the underlying mechanisms of diastolic dysfunction in HFpEF mouse models and may help develop new treatments for this condition.

Autor em destaque: investigando a função cardíaca dependente de FC em modelos de camundongos por meio de uma nova abordagem de estimulação atrial 

The present protocol describes obtaining the pressure-volume relationship through transesophageal pacing, which serves as a valuable tool in evaluating diastolic function&#160;in mouse models of heart failure.

Um procedimento de estimulação cardíaca controlada para avaliação das funções diastólicas dependentes da frequência cardíaca em modelos murinos de insuficiência cardíaca