Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 20 de 25
Arq. bras. cardiol ; 118(2): 463-475, 2022. tab, graf
Article in English, Portuguese | LILACS | ID: biblio-1364328


Resumo Fundamento O remodelamento cardíaco patológico se caracteriza por disfunção diastólica e sistólica, levando à insuficiência cardíaca. Neste contexto, o cenário disfuncional do trânsito de cálcio miocárdico (Ca2+) tem sido pouco estudado. Um modelo experimental de estenose aórtica tem sido extensamente utilizado para aprimorar os conhecimentos sobre os principais mecanismos do remodelamento patológico cardíaco. Objetivo Entender o processo disfuncional dos principais componentes responsáveis pelo equilíbrio do cálcio miocárdico e sua influência sobre a função cardíaca na insuficiência cardíaca induzida pela estenose aórtica. Métodos Ratos Wistar de 21 dias de idade foram distribuídos em dois grupos: controle (placebo; n=28) e estenose aórtica (EaO; n=18). A função cardíaca foi analisada com o ecocardiograma, músculo papilar isolado e cardiomiócitos isolados. No ensaio do músculo papilar, SERCA2a e a atividade do canal de Ca2+ do tipo L foram avaliados. O ensaio de cardiomiócitos isolados avaliou o trânsito de cálcio. A expressão proteica da proteínas do trânsito de cálcio foi analisada com o western blot. Os resultados foram estatisticamente significativos quando p <0,05. Resultados Os músculos papilares e cardiomiócitos dos corações no grupo EaO demonstraram falhas mecânicas. Os ratos com EaO apresentaram menor tempo de pico do Ca2+, menor sensibilidade das miofibrilas do Ca2+, prejuízos nos processos de entrada e recaptura de cálcio pelo retículo sarcoplasmático, bem como disfunção no canal de cálcio do tipo L (CCTL). Além disso, os animais com EaO apresentaram maior expressão de SERCA2a, CCTL e trocador de Na+/Ca2+. Conclusão Insuficiência cardíaca sistólica e diastólica devido à estenose aórtica supravalvular acarretou comprometimento da entrada de Ca2+ celular e inibição da recaptura de cálcio pelo retículo sarcoplasmático devido à disfunção no CCTL e SERCA2a, assim como mudanças no trânsito de cálcio e na expressão das principais proteínas responsáveis pela homeostase de Ca2+ celular.

Abstract Background Maladaptive cardiac remodelling is characterized by diastolic and systolic dysfunction, culminating in heart failure. In this context, the dysfunctional scenario of cardiac calcium (Ca2+) handling has been poorly studied. An experimental model of aortic stenosis has been extensively used to improve knowledge about the key mechanisms of cardiac pathologic remodelling. Objective To understand the dysfunctional process of the major components responsible for Ca2+ balance and its influence on cardiac function in heart failure induced by aortic stenosis. Methods Male 21-day-old Wistar rats were distributed into two groups: control (sham; n= 28) and aortic stenosis (AoS; n= 18). Cardiac function was analysed by echocardiogram, isolated papillary muscle, and isolated cardiomyocytes. In the papillary muscle assay, SERCA2a and L-type Ca2+ channel activity was evaluated. The isolated cardiomyocyte assay evaluated Ca2+ handling. Ca2+ handling protein expression was analysed by western blot. Statistical significance was set at p <0.05. Results Papillary muscles and cardiomyocytes from AoS hearts displayed mechanical malfunction. AoS rats presented a slower time to the Ca2+ peak, reduced Ca2+ myofilament sensitivity, impaired sarcoplasmic reticulum Ca2+ influx and reuptake ability, and SERCA2a and L-type calcium channel (LTCC) dysfunction. Moreover, AoS animals presented increased expression of SERCA2a, LTCCs, and the Na+/Ca2+ exchanger. Conclusion Systolic and diastolic heart failure due to supravalvular aortic stenosis was paralleled by impairment of cellular Ca2+ influx and inhibition of sarcoplasmic reticulum Ca2+ reuptake due to LTCC and SERCA2a dysfunction, as well as changes in Ca2+ handling and expression of the major proteins responsible for cellular Ca2+ homeostasis.

Animals , Male , Rats , Aortic Valve Stenosis/pathology , Heart Failure/pathology , Papillary Muscles , Calcium/metabolism , Rats, Wistar , Myocytes, Cardiac/pathology , Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism , Myocardial Contraction/physiology
Braz. j. med. biol. res ; 53(2): e9106, 2020. graf
Article in English | LILACS | ID: biblio-1055491


Reperfusion strategies in acute myocardial infarction (AMI) can cause a series of additional clinical damage, defined as myocardial ischemia/reperfusion (I/R) injury, and thus there is a need for effective therapeutic methods to attenuate I/R injury. miR-26a-5p has been proven to be an essential regulator for biological processes in different cell types. Nevertheless, the role of miR-26a-5p in myocardial I/R injury has not yet been reported. We established an I/R injury model in vitro and in vivo. In vitro, we used cardiomyocytes to simulate I/R injury using hypoxia/reoxygenation (H/R) assay. In vivo, we used C57BL/6 mice to construct I/R injury model. The infarct area was examined by TTC staining. The level of miR-26a-5p and PTEN was determined by bioinformatics methods, qRT-PCR, and western blot. In addition, the viability and apoptosis of cardiomyocytes were separately detected by MTT and flow cytometry. The targeting relationship between miR-26a-5p and PTEN was analyzed by the TargetScan website and luciferase reporter assay. I/R and H/R treatment induced myocardial tissue injury and cardiomyocyte apoptosis, respectively. The results showed that miR-26a-5p was down-regulated in myocardial I/R injury. PTEN was found to be a direct target of miR-26a-5p. Furthermore, miR-26a-5p effectively improved viability and inhibited apoptosis in cardiomyocytes upon I/R injury by inhibiting PTEN expression to activate the PI3K/AKT signaling pathway. miR-26a-5p could protect cardiomyocytes against I/R injury by regulating the PTEN/PI3K/AKT pathway, which offers a potential approach for myocardial I/R injury treatment.

Animals , Rabbits , Myocardial Reperfusion Injury/metabolism , Myocardial Ischemia/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Myocytes, Cardiac/pathology , MicroRNAs/metabolism , PTEN Phosphohydrolase/metabolism , Signal Transduction , Blotting, Western , Disease Models, Animal , Proto-Oncogene Proteins c-akt/metabolism , Real-Time Polymerase Chain Reaction , Flow Cytometry , Mice, Inbred C57BL
Braz. j. med. biol. res ; 52(3): e7994, 2019. graf
Article in English | LILACS | ID: biblio-984040


Myocardial infarction (MI) is a common presentation for ischemic heart disease, which is a leading cause of death. Emodin is a Chinese herbal anthraquinone used in several diseases. However, the effect of emodin in hypoxia-induced injury in cardiomyocytes has not been clearly elucidated. Our study aimed to clarify the functions of emodin in hypoxia-induced injury in rat cardiomyocytes H9c2 and explore the underlying mechanism. The effects of emodin on cell viability and apoptosis were analyzed by the Cell counting kit-8 assay and flow cytometry assay, respectively. The cell proliferation- and cell apoptosis-related proteins were detected by western blot. qRT-PCR was used to determine the relative expression of miR-138. Cell transfection was performed to alter miR-138 and MLK3 expression. miR-138 target was performed by dual luciferase activity assay. Sirt1/AKT and Wnt/β-catenin pathways-related factors phosphorylation were analyzed by western blot. Emodin inhibited hypoxia-induced injury in H9c2 cells by promoting cell viability and reducing cell apoptosis. miR-138 was down-regulated by hypoxia treatment but up-regulated by emodin. Up-regulation of miR-138 alleviated hypoxia-induced cell injury. Down-regulation of miR-138 attenuated the growth-promoting effect of emodin on hypoxia-induced injury, whereas up-regulation of miR-138 enhanced the growth-promoting effects of emodin. The underlying mechanism might be by inactivating Sirt1/AKT and Wnt/β-catenin pathways. MLK3 was negatively regulated by miR-138 expression and inactivated Sirt1/AKT and Wnt/β-catenin pathways. Emodin alleviated hypoxia-induced injury in H9c2 cells via up-regulation of miR-138 modulated by MLK3, as well as by activating Sirt1/AKT and Wnt/β-catenin pathways.

Animals , Rats , Cell Hypoxia/drug effects , Cell Survival/drug effects , Emodin/therapeutic use , Myocytes, Cardiac/pathology , Cell Proliferation/drug effects , Hypoxia/complications , Signal Transduction , Up-Regulation , Cell Line , Myocytes, Cardiac/drug effects , MicroRNAs
Braz. j. med. biol. res ; 52(12): e8834, 2019. graf
Article in English | LILACS | ID: biblio-1055472


Polydatin (PD), a monocrystalline polyphenolic drug mainly found in the roots of Polygonum cuspidatum, has various pharmacological activities. Long non-coding RNAs (lncRNA) DiGeorge syndrome critical region gene 5 (DGCR5) was found to participate in the suppression of multiple cancers. Here, we proposed to study the effect of PD on myocardial infarction (MI) by inducing DGCR5. CCK-8 assay was performed to detect the viability of H9c2 cells. Flow cytometry was utilized to test apoptosis of H9c2 cells. These results determined the optimal concentration and effect time of hypoxia as well as PD. Si-DGCR5 was transfected into cells and the expression level was determined by qRT-PCR. Western blot was utilized to evaluate the expression of apoptosis-related proteins, Bcl-2, Bax, and cleaved-caspase-3, as well as autophagy-associated proteins including Beclin-1, p62, and LC3-II/LC3-I. As a result, PD efficiently attenuated hypoxia-induced apoptosis and autophagy in H9c2 cells. The expression of DGCR5 was down-regulated by hypoxia and up-regulated by PD. Besides, knocking-down the expression of DGCR5 inhibited the protection of PD in H9c2 cells. In addition, PD up-regulated the accumulation of DGCR5, DGCR5 decreased the expression of Bcl-2 and p62, raised the expression of Bax and cleaved-caspase-3, and the proportion of LC3-II/LC3-I. PD stimulated the PI3K/AKT/mTOR and MEK/ERK signaling pathways via up-regulating the expression of DGCR5. Our data demonstrated that PD reduced cell apoptosis and autophagy induced by hypoxia in cardiomyocytes. Moreover, PD activated PI3K/AKT/mTOR and MEK/ERK signaling pathways by up-regulating the expression of DGCR5.

Animals , Rats , Stilbenes/pharmacology , Cell Hypoxia/drug effects , Apoptosis/drug effects , Myocytes, Cardiac/drug effects , Cell Proliferation/drug effects , RNA, Long Noncoding/drug effects , Glucosides/pharmacology , Signal Transduction , Up-Regulation/drug effects , Cell Line , Cytoprotection , Myocytes, Cardiac/metabolism , Myocytes, Cardiac/pathology
Braz. j. med. biol. res ; 52(7): e8732, 2019. tab, graf
Article in English | LILACS | ID: biblio-1011598


Inflammation plays an important role in the development of cardiovascular diseases (CVDs), suggesting that the immune system is a target of therapeutic interventions used for treating CVDs. This study evaluated mechanisms underlying inflammatory response and cardiomyocyte hypertrophy associated with bacterial lipopolysaccharide (LPS)- or heat shock protein 60 (HSP60)-induced Toll-like receptor (TLR) stimulation and the effect of a small interfering RNA (siRNA) against Ca2+/calmodulin-dependent kinase II delta B (CaMKIIδB) on these outcomes. Our results showed that treatment with HSP60 or LPS (TLR agonists) induced cardiomyocyte hypertrophy and complement system C3 and factor B gene expression. In vitro silencing of CaMKIIδB prevented complement gene transcription and cardiomyocyte hypertrophy associated with TLR 2/4 activation but did not prevent the increase in interleukin-6 and tumor necrosis factor-alfa gene expression in primary cultured cardiomyocytes. Moreover, CaMKIIδB silencing attenuated nuclear factor-kappa B expression. These findings supported the hypothesis that CaMKIIδB acts as a link between inflammation and cardiac hypertrophy. Furthermore, the present study is the first to show that extracellular HSP60 activated complement gene expression through CaMKIIδB. Our results indicated that a stress stimulus induced by LPS or HSP60 treatment promoted cardiomyocyte hypertrophy and initiated an inflammatory response through the complement system. However, CaMKIIδB silencing prevented the cardiomyocyte hypertrophy independent of inflammatory response induced by LPS or HSP60 treatment.

Animals , Rats , Myocytes, Cardiac/pathology , Toll-Like Receptors/metabolism , Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism , Signal Transduction/physiology , Gene Expression , Lipopolysaccharides/pharmacology , NF-kappa B/metabolism , Rats, Wistar , Chaperonin 60/pharmacology , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/metabolism , RNA, Small Interfering , Inflammation/metabolism
Arq. bras. cardiol ; 111(2): 162-169, Aug. 2018. graf
Article in English | LILACS | ID: biblio-950215


Abstract Background: Pioglitazone has been widely used as an insulin-sensitizing agent for improving glycemic control in patients with type 2 diabetes mellitus. However, cardiovascular risk and protective effects of pioglitazone remain controversial. Objectives: In this study, we investigated whether pioglitazone affects cardiomyocyte apoptosis and hypertrophy by regulating the VEGFR-2 signaling pathway. Methods: Cardiomyocytes were enzymatically isolated from 1- to 3-day-old Sprague-Dawley rat ventricles. Effects of pioglitazone and the VEGFR-2-selective inhibitor apatinib on cardiomyocyte apoptotic rate was determined using flow cytometry, and hypertrophy was evaluated using [3H]-leucine incorporation. The protein expressions of unphosphorylated and phosphorylated VEGFR-2, Akt, P53, and mTOR were determined by Western-Blotting. Analysis of variance (ANOVA) was used to assess the differences between groups. Results: Pioglitazone and VEGFR-2-selective inhibitor apatinib reduced rat cardiomyocyte viability and cardiomyocyte hypertrophy induced by angiotensin II in vitro. Furthermore, in the same in vitro model, pioglitazone and apatinib significantly increased the expression of Bax and phosphorylated P53 and decreased the expression of phosphorylated VEGFR-2, Akt, and mTOR, which promote cardiomyocyte hypertrophy. Conclusions: These findings indicate that pioglitazone induces cardiomyocyte apoptosis and inhibits cardiomyocyte hypertrophy by modulating the VEGFR-2 signaling pathway.

Resumo Fundamento: A pioglitazona tem sido amplamente utilizada como droga sensibilizadora da insulina para melhorar o controle glicêmico em pacientes com diabetes mellitus tipo 2. No entanto, o risco cardiovascular bem como os efeitos protetores da pioglitazona ainda são controversos. Objetivos: Neste estudo, investigamos se os efeitos da pioglitazona sobre a apoptose e a hipertrofia de cardiomiócitos ocorrem via regulação da via de sinalização do VEGFR-2. Métodos: os cardiomiócitos foram isolados enzimaticamente dos ventrículos de ratos Sprague-Dawley de 1-3 anos de vida. Os efeitos da pioglitazona e do inibidor seletivo de VEGFR-2 apatinib sobre a taxa de apoptose dos cardiomiócitos foram avaliados por citometria de fluxo, e a hipertrofia avaliada por incorporação de leucina-[3H]. As expressões de VEGFR-2, Akt, P53, e mTOR fosforiladas e não fosforiladas foram determinadas por Western Blotting. Análise de variância (ANOVA) foi usada para avaliar diferenças entre os grupos. Resultados: a pioglitazona e o apatinib reduziram a viabilidade e a hipertrofia de cardiomiócitos induzida por angiotensina II in vitro. Além disso, no mesmo modelo in vitro, a pioglitazona e o apatinib aumentaram significativamente a expressão de Bax e P53 fosforilada, e diminuiu a expressão de VEGFR-2, Akt, e mTOR, que promove hipertrofia de cardiomiócitos. Conclusões: Esses resultados indicam que a pioglitazona induz a apoptose e inibe a hipertrofia de cardiomiócitos pela modulação da via de sinalização de VEGFR-2.

Animals , Rats , Apoptosis/drug effects , Vascular Endothelial Growth Factor Receptor-2/drug effects , Thiazolidinediones/pharmacology , Hypoglycemic Agents/pharmacology , Signal Transduction/drug effects , Rats, Sprague-Dawley , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/pathology , Pioglitazone , Hypertrophy/chemically induced , Hypertrophy/pathology , Animals, Newborn
Acta cir. bras ; 33(4): 306-313, Apr. 2018. tab, graf
Article in English | LILACS | ID: biblio-886286


Abstract Purpose: To investigate the cause of congenital anomalies resulted from gestational diabetes on fetal cardiac tissue in experimental animal study model. Methods: Totally 12 female Wistar albino rats were divided into two groups, each consisting of 6 rats. Streptozotocin (60 mg/kg) was administered intraperitoneally to the study group by dissolving in citrate solution. The rats with a blood glucose level of 200 mg/dL and above were considered to be diabetic rats. Total antioxidant status (TAS), total oxidative stress (TOS) and oxidative stress index (OSI) values were calculated in the cardiac tissues and maternal serum samples of the fetuses delivered by cesarean section after the mating process. The cardiac tissues were also subjected to histopathological examination. Results: TOS and OSI values in fetal cardiac tissues of the diabetic rats were found to be significantly higher than that of the control group (p=0.026 and p=0.005). Histopathological examination revealed that the mitotic index was lower and the cell organization was found to be damaged in the fetuses of the study group rats. Conclusion: Increased levels of free oxygen radicals considered to be due to hyperglycemia may cause congenital anomalies, especially during organogenesis period, by disrupting cell homeostasis and adversely affecting mitosis.

Animals , Female , Pregnancy , Diabetes, Gestational , Diabetes Mellitus, Experimental/complications , Heart/embryology , Heart Defects, Congenital/etiology , Heart Defects, Congenital/pathology , Myocardium/pathology , Reference Values , Blood Glucose/analysis , Rats, Wistar , Streptozocin , Oxidative Stress , Myocytes, Cardiac/pathology , Heart Defects, Congenital/embryology , Hyperglycemia/complications , Microscopy , Antioxidants/analysis
Arq. bras. cardiol ; 110(3): 278-288, Mar. 2018. tab, graf
Article in English | LILACS | ID: biblio-888039


Abstract Many non-invasive methods, such as imaging tests, have been developed aiming to add a contribution to existing studies in estimating patients' prognosis after myocardial injury. This prognosis is proportional to myocardial viability, which is evaluated in coronary artery disease and left ventricular dysfunction patients only. While myocardial viability represents the likelihood of a dysfunctional muscle (resulting from decreased oxygen supply for coronary artery obstruction), hibernation represents post-interventional functional recovery itself. This article proposes a review of pathophysiological basis of viability, diagnostic methods, prognosis and future perspectives of myocardial viability. An electronic bibliographic search for articles was performed in PubMed, Lilacs, Cochrane and Scielo databases, according to pre-established criteria. The studies showed the ability of many imaging techniques in detecting viable tissues in dysfunctional areas of left ventricle resulting from coronary artery injuries. These techniques can identify patients who may benefit from myocardial revascularization and indicate the most appropriate treatment.

Resumo Diversos métodos não invasivos, como novos exames de imagem, vem sendo aprimorados, a fim de somar esforços com os atuais em estimar o prognóstico de pacientes pós-injúria miocárdica. Este prognóstico é proporcional à viabilidade miocárdica, a qual tem sua avaliação reservada para pacientes portadores de doença arterial coronariana e insuficiência ventricular esquerda. Enquanto a viabilidade miocárdica se mostra como a capacidade de recuperação funcional do músculo com disfunção por redução de oxigênio fornecido por artérias coronárias obstruídas, a hibernação consiste na própria recuperação funcional após intervenções. Este artigo propõe uma revisão sobre as bases fisiopatológicas do processo de viabilidade, métodos diagnósticos disponíveis, prognóstico e perspectivas para o futuro acerca dessa condição. Realizou-se pesquisa de busca bibliográfica informatizada em bases eletrônicas de dados, como PubMed, Lilacs, Cochrane e Scielo, onde foram selecionados os estudos de acordo com critérios pré-determinados. Os estudos demonstram a capacidade de várias técnicas de imagem de identificar tecido viável em regiões disfuncionais do ventrículo esquerdo em decorrência de lesões em artérias coronárias. Estas técnicas podem identificar pacientes com potencial benefício da revascularização miocárdica e orientar o tratamento mais adequado.

Humans , Tissue Survival/physiology , Myocytes, Cardiac/pathology , Myocardial Infarction/pathology , Myocardial Infarction/diagnostic imaging , Myocardium/pathology , Prognosis , Coronary Artery Disease/physiopathology , Coronary Artery Disease/pathology , Coronary Artery Disease/diagnostic imaging , Magnetic Resonance Imaging/methods , Echocardiography/methods , Ventricular Dysfunction, Left/pathology , Ventricular Dysfunction, Left/diagnostic imaging , Positron Emission Tomography Computed Tomography/methods , Heart/diagnostic imaging , Myocardial Infarction/physiopathology , Myocardial Revascularization
Arq. bras. cardiol ; 110(1): 44-51, Jan. 2018. graf
Article in English | LILACS | ID: biblio-887998


Resumo Background: Melatonin is a neuroendocrine hormone synthesized primarily by the pineal gland that is indicated to effectively prevent myocardial reperfusion injury. It is unclear whether melatonin protects cardiac function from reperfusion injury by modulating intracellular calcium homeostasis. Objective: Demonstrate that melatonin protect against myocardial reperfusion injury through modulating IP3R and SERCA2a to maintain calcium homeostasis via activation of ERK1 in cardiomyocytes. Methods: In vitro experiments were performed using H9C2 cells undergoing simulative hypoxia/reoxygenation (H/R) induction. Expression level of ERK1, IP3R and SERCA2a were assessed by Western Blots. Cardiomyocytes apoptosis was detected by TUNEL. Phalloidin-staining was used to assess alteration of actin filament organization of cardiomyocytes. Fura-2 /AM was used to measure intracellular Ca2+ concentration. Performing in vivo experiments, myocardial expression of IP3R and SERCA2a were detected by immunofluorescence staining using myocardial ischemia/ reperfusion (I/R) model in rats. Results: In vitro results showed that melatonin induces ERK1 activation in cardiomyocytes against H/R which was inhibited by PD98059 (ERK1 inhibitor). The results showed melatonin inhibit apoptosis of cardiomyocytes and improve actin filament organization in cardiomyocytes against H/R, because both could be reversed by PD98059. Melatonin was showed to reduce calcium overload, further to inhibit IP3R expression and promote SERCA2a expression via ERK1 pathway in cardiomyocytes against H/R. Melatonin induced lower IP3R and higher SERCA2a expression in myocardium that were reversed by PD98059. Conclusion: melatonin-induced cardioprotection against reperfusion injury is at least partly through modulation of IP3R and SERCA2a to maintain intracellular calcium homeostasis via activation of ERK1.

Resumo Fundamento: A melatonina é um hormônio neuroendócrino sintetizado principalmente pela glândula pineal que é indicado para prevenir efetivamente a lesão de reperfusão miocárdica. Não está claro se a melatonina protege a função cardíaca da lesão de reperfusão através da modulação da homeostase do cálcio intracelular. Objetivo: Demonstrar que a melatonina protege contra a lesão de reperfusão miocárdica através da modulação de IP3R e SERCA para manter a homeostase de cálcio por meio da ativação de ERK1 em cardiomiócitos. Métodos: Foram realizados experimentos in vitro usando células H9C2 submetidas a indução de hipoxia / reoxigenação simulada (H/R). O nível de expressão de ERK1, IP3R e SERCA foi avaliado por Western Blots. A apoptose de cardiomiócitos foi detectada por TUNEL. A coloração de faloidina foi utilizada para avaliar a alteração da organização de filamentos de actina dos cardiomiócitos. Fura-2 / AM foi utilizado para medir a concentração intracelular de Ca2+. Realizando experiências in vivo, a expressão miocárdica de IP3R e SERCA foi detectada por coloração com imunofluorescência usando modelo de isquemia miocárdica / reperfusão (I/R) em ratos. Resultados: resultados in vitro mostraram que a melatonina induz a ativação de ERK1 em cardiomiócitos contra H/R que foi inibida por PD98059 (inibidor de ERK1). Os resultados mostraram que a melatonina inibe a apoptose dos cardiomiócitos e melhora a organização do filamento de actina em cardiomiócitos contra H/R, pois ambas poderiam ser revertidas pela PD98059. A melatonina mostrou reduzir a sobrecarga de cálcio, além de inibir a expressão de IP3R e promover a expressão de SERCA através da via ERK1 em cardiomiócitos contra H/R. A melatonina induziu menor IP3R e maior expressão de SERCA no miocárdio que foram revertidas pela PD98059. Conclusão: a cardioproteção induzida pela melatonina contra lesão de reperfusão é pelo menos parcialmente através da modulação de IP3R e SERCA para manter a homeostase de cálcio intracelular via ativação de ERK1.

Animals , Male , Rats , Myocardial Reperfusion Injury/metabolism , Myocardial Reperfusion Injury/prevention & control , MAP Kinase Signaling System/drug effects , Myocytes, Cardiac/drug effects , Sarcoplasmic Reticulum Calcium-Transporting ATPases/drug effects , Inositol 1,4,5-Trisphosphate Receptors/drug effects , Melatonin/pharmacology , Myocardial Reperfusion Injury/pathology , Rats, Sprague-Dawley , Myocytes, Cardiac/pathology , Disease Models, Animal , Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism , Inositol 1,4,5-Trisphosphate Receptors/metabolism
Arq. bras. cardiol ; 108(5): 458-469, May 2017. tab, graf
Article in English | LILACS | ID: biblio-838739


Abstract The study of myocardial viability is of great importance in the orientation and management of patients requiring myocardial revascularization or angioplasty. The technique of delayed enhancement (DE) is accurate and has transformed the study of viability into an easy test, not only for the detection of fibrosis but also as a binary test detecting what is viable or not. On DE, fibrosis equal to or greater than 50% of the segmental area is considered as non-viable, whereas that below 50% is considered viable. During the same evaluation, cardiac magnetic resonance (CMR) may also use other techniques for functional and perfusion studies to obtain a global evaluation of ischemic heart disease. This study aims to highlight the current concepts and broadly emphasize the use of CMR as a method that over the last 20 years has become a reference in the detection of infarction and assessment of myocardial viability.

Resumo O estudo de viabilidade miocárdica é de grande importância para a orientação e manejo de pacientes que necessitam de cirurgia de revascularização miocárdica ou angioplastia. A técnica de realce tardio (RT) é precisa e transformou o estudo de viabilidade em um teste fácil, não só para a detecção de fibrose, mas também como um modelo binário para a detecção do que é ou não é viável. Uma fibrose identificada pelo RT é considerada como não viável quando igual ou maior do que 50% da área segmentar e como viável quando menor que 50%. A ressonância magnética cardíaca (RMC) também pode lançar mão de outras técnicas para estudo funcional e de perfusão para uma avaliação global da doença isquêmica do coração no mesmo exame. Este estudo tem como objetivo destacar os conceitos atuais e enfatizar amplamente o uso da RMC como um método que nos últimos 20 anos se tornou referência na detecção de infarto e avaliação de viabilidade miocárdica.

Humans , Tissue Survival/physiology , Magnetic Resonance Imaging/methods , Myocardial Infarction/diagnostic imaging , Magnetic Resonance Imaging/standards , Magnetic Resonance Imaging/trends , Contrast Media/standards , Myocytes, Cardiac/pathology , Cardiomyopathies/physiopathology , Cardiomyopathies/diagnostic imaging , Myocardial Infarction/physiopathology , Myocardial Revascularization
Braz. j. med. biol. res ; 50(2): e5760, 2017. graf
Article in English | LILACS | ID: biblio-839255


Cardiomyocyte apoptosis plays key roles in the pathogenesis of heart diseases such as myocardial infarction. MicroRNAs are important regulators of gene expression, which are also involved in the regulation of cardiomyocyte apoptosis. However, cardiomyocyte apoptosis regulated by microRNA (miR)-122 is largely unexplored. The aim of this study focused on the role of miR-122 in cardiomyocyte apoptosis. Cardiomyocytes were isolated from neonatal mice and primarily cultured. MiR-122 mimic and inhibitor were transfected to cardiomyocytes and verified by qRT-PCR. Cell viability and apoptosis post-transfection were assessed by MTT assay and flow cytometry, respectively. Changes in expression of caspase-8 were quantified by qRT-PCR and western blot. Results showed that miR-122 mimic and inhibitor successfully induced changes in miR-122 levels in cultured cardiomyocytes (P<0.01). MiR-122 overexpression suppressed viability and promoted apoptosis of cardiomyocytes (P<0.05), and miR-122 knockdown promoted cell viability and inhibited apoptosis (P<0.05). The mRNA and protein levels of caspase-8 were elevated by miR-122 overexpression (P<0.01) and reduced by miR-122 knockdown (P<0.001). These results suggest an inductive role of miR-122 in cardiomyocyte apoptosis, which may be related to its regulation on caspase-8.

Animals , Mice , Apoptosis/genetics , Caspase 8/genetics , Gene Expression/genetics , MicroRNAs/genetics , MicroRNAs/physiology , Myocytes, Cardiac/pathology , Animals, Newborn , Gene Expression/physiology , Mice, Inbred BALB C
Braz. j. med. biol. res ; 50(2): e5286, 2017. tab, graf
Article in English | LILACS | ID: biblio-839258


We aimed to study the effect of fentanyl (Fen) preconditioning on cardiomyocyte apoptosis induced by ischemia-reperfusion (I/R) in rats. A total of 120 Sprague Dawley male rats (age: 3 months) were randomly divided into: sham operation group (S group), I/R group, normal saline I/R group (NS group), and fentanyl low, middle, and high dose groups (Fen1: 2 μg/kg; Fen2: 4 μg/kg; Fen3: 6 μg/kg). Heart rate (HR), mean arterial pressure (MAP), left ventricular developed pressure (LVDP), ±dp/dtmax, malondialdehyde (MDA), superoxide dismutase (SOD) activity, creatine phosphokinase-MB (CK-MB), and cardiac troponin-I (cTnI) were measured. Myocardial ischemic (MI) area, total apoptotic myocardial cells, and protein and mRNA expressions of B-cell lymphoma 2 (Bcl-2) and Bax were detected. HR and MAP were higher, while LVDP and ±dp/dtmax were close to the base value in the Fen groups compared to those in the I/R group. Decreased MDA concentration and CK-MB value and increased SOD activity were found in the Fen groups compared to the I/R group, while cTnI concentration was significantly lower in the Fen1 and Fen2 groups (all P<0.05). Myocardial damage was less in the Fen groups compared to the I/R group and the MI areas and apoptotic indexes were significantly lower in the Fen1 and Fen2 groups (all P<0.05). Furthermore, significantly increased protein and mRNA expressions of Bcl-2, and decreased protein and mRNA expressions of Bax were found in the Fen groups compared to the I/R group (all P<0.05). Fentanyl preconditioning may suppress cardiomyocyte apoptosis induced by I/R in rats by regulating Bcl-2 and Bax.

Animals , Male , Rats , Apoptosis/drug effects , Fentanyl/therapeutic use , Myocardial Reperfusion Injury/prevention & control , Myocytes, Cardiac/drug effects , Protective Agents/therapeutic use , Myocardial Reperfusion Injury/pathology , Myocytes, Cardiac/pathology , Rats, Sprague-Dawley
Arq. bras. cardiol ; 107(1): 33-39, July 2016. tab, graf
Article in English | LILACS | ID: lil-792492


Abstract Background: Right-sided heart failure has high morbidity and mortality, and may be caused by pulmonary arterial hypertension. Fractal dimension is a differentiated and innovative method used in histological evaluations that allows the characterization of irregular and complex structures and the quantification of structural tissue changes. Objective: To assess the use of fractal dimension in cardiomyocytes of rats with monocrotaline-induced pulmonary arterial hypertension, in addition to providing histological and functional analysis. Methods: Male Wistar rats were divided into 2 groups: control (C; n = 8) and monocrotaline-induced pulmonary arterial hypertension (M; n = 8). Five weeks after pulmonary arterial hypertension induction with monocrotaline, echocardiography was performed and the animals were euthanized. The heart was dissected, the ventricles weighed to assess anatomical parameters, and histological slides were prepared and stained with hematoxylin/eosin for fractal dimension analysis, performed using box-counting method. Data normality was tested (Shapiro-Wilk test), and the groups were compared with non-paired Student t test or Mann Whitney test (p < 0.05). Results: Higher fractal dimension values were observed in group M as compared to group C (1.39 ± 0.05 vs. 1.37 ± 0.04; p < 0.05). Echocardiography showed lower pulmonary artery flow velocity, pulmonary acceleration time and ejection time values in group M, suggesting function worsening in those animals. Conclusion: The changes observed confirm pulmonary-arterial-hypertension-induced cardiac dysfunction, and point to fractal dimension as an effective method to evaluate cardiac morphological changes induced by ventricular dysfunction.

Resumo Fundamento: Insuficiência cardíaca direita apresenta grande morbimortalidade e pode ser causada por hipertensão arterial pulmonar. Um método diferenciado e inovador utilizado em avaliações histológicas é a dimensão fractal, que permite a caracterização de estruturas irregulares e complexas e pode quantificar alterações estruturais dos tecidos. Objetivo: Avaliar a utilização do método da dimensão fractal nos cardiomiócitos de ratos com hipertensão arterial pulmonar induzida por monocrotalina, associada com análise histológica e funcional. Métodos: Ratos Wistar machos foram divididos em 2 grupos: controle (C; n = 8) e hipertensão arterial pulmonar induzida por monocrotalina (M; n = 8). Após 5 semanas da indução da hipertensão arterial pulmonar pela monocrotalina, foi realizado ecocardiograma. Os animais foram eutanasiados, o coração dissecado e os ventrículos pesados para avaliação dos parâmetros anatômicos. Lâminas histológicas foram confeccionadas, coradas com hematoxilina/eosina para análise da dimensão fractal, realizada pelo método box-counting . Inicialmente foi testada a normalidade dos dados (teste Shapiro Wilk) e a comparação entre os grupos foi por meio do teste t de Student não pareado ou teste de Mann Whitney (p < 0,05). Resultados: Maiores valores da dimensão fractal foram observados no grupo M em comparação ao C (1,43 ± 0,06 vs. 1,37 ± 0,04; p < 0,05). O ecocardiograma apontou menores valores no grupo M para velocidade máxima pulmonar, tempo de aceleração pulmonar e tempo de ejeção, sugerindo piora funcional nesses animais, que também apresentaram hipertrofia cardíaca. Conclusão: As alterações observadas comprovam a disfunção cardíaca induzida pela hipertensão arterial pulmonar e apontam que a dimensão fractal é um método eficaz para avaliar alterações morfológicas cardíacas induzidas pela disfunção ventricular.

Animals , Male , Fractals , Heart Failure/etiology , Heart Failure/pathology , Hypertension, Pulmonary/complications , Hypertension, Pulmonary/pathology , Reference Values , Stroke Volume/physiology , Echocardiography , Reproducibility of Results , Monocrotaline , Rats, Wistar , Ventricular Dysfunction, Right/physiopathology , Ventricular Dysfunction, Right/pathology , Ventricular Dysfunction, Left/physiopathology , Ventricular Dysfunction, Left/pathology , Myocytes, Cardiac/pathology , Disease Models, Animal , Heart Failure/physiopathology , Hypertension, Pulmonary/physiopathology
Pesqui. vet. bras ; 36(2): 67-72, fev. 2016. tab, graf
Article in Portuguese | LILACS | ID: lil-777387


Ao que tudo indica, o monofluoroacetato de sódio (MF) é o princípio tóxico das numerosas plantas que causam "morte súbita" no Brasil. Eventualmente, observam-se, nos animais intoxicados por MF, grupos de cardiomiócitos com aumento da eosinofilia citoplasmática. Essas alterações cardíacas, no entanto, na maioria dos casos, ainda são incipientes, de difícil interpretação, não há reação inflamatória e devem ser diferenciadas de artefato. O presente trabalho teve como objetivo detectar a presença de alterações regressivas precoces no miocárdio de bovinos e ovinos intoxicados experimentalmente por MF, através da imuno-histoquímica com troponina C (cTnC). Fragmentos de coração de seis bovinos (três que receberam, por via oral, doses únicas de 0,5mg/kg e, os demais, 1,0mg/kg de MF) e cinco ovinos (um recebeu, por via oral, dose única de 0,5mg/kg, outros dois receberam doses de 1,0mg/kg; um ovino recebeu, por via oral, doses subletais repetidas diariamente de 0,1mg/kg/dia, por quatro dias, e outro, 0,2mg/kg/dia por seis dias) foram submetidos à técnica de imuno-histoquímica com anticorpo anti-cTnC. Nos cardiomiócitos dos bovinos e ovinos verificou-se redução dos níveis de expressão da cTnC no citoplasma de grupos de fibras musculares. Diminuição significativa na imunorreatividade ocorreu, sobretudo, em cardiomiócitos que apresentavam, no exame histopatológico, aumento da eosinofilia citoplasmática. A diminuição ou ausência da expressão da cTnC nos animais intoxicados por MF permitiu estabelecer a diferença entre necrose coagulativa de cardiomiócitos e artefato ocasionado pelo fixador. Isso indica que este método pode ser utilizado com segurança para identificação de lesões regressivas precoces, ou não, no miocárdio, independentemente da causa. Adicionalmente, é possível afirmar que, dependendo do tempo de evolução, a toxicose por MF, bem como por plantas causadoras de "morte súbita" em bovinos e ovinos, podem cursar com lesões necrotizantes no miocárdio.

Sodium monofluoroacetate (MF) is the toxic principle of several plants that cause "sudden death" of cattle in Brazil. Groups of cardiomyocites with high cytoplasmic eosinophilia are sometimes observed in animals poisoned by MF. However, this cardiac alteration is difficult to interpret, as there is no inflammatory reaction and it must be differentiated from artifacts. The present study had the objective to detect the presence of early regressive lesions in the myocardium of sheep and cattle experimentally poisoned by MF through immunohistochemistry with troponin C (cTnC). Fragments of the heart muscle from six cattle (three received, orally, single doses of 0.5mg/kg and the others, single doses of 1.0mg/kg) and five sheep (one received, orally, single dose of 0.5mg/kg, the other two received single doses of 1.0mg/kg, one received sublethal daily doses of 0.1mg/kg for four days, and another received daily sublethal doses of 0.2mg/kg for six days) were submitted to immunohistochemistry with antibody anti-cTnC. In the cardiomyocites of cattle and sheep, it was possible to observe reduction of the expression levels for cTnC in the cytoplasm of groups of cardiac muscle fibers. Significant reduction of immunoreactivity ocurred overall in cardiomyocites that presented high cytoplasmic eosinophilia. The decrease or absence of expression for cTnC in animals poisoned by MF allowed to estabilish the difference between coagulative necrosis of cardiomyocites and artifacts caused by fixation. This indicates that this method can be used safely to identify any lesions, early regressive or not, in the myocardium independently of the cause. It is also possible to affirm that poisoning by MF as well as the one caused by "sudden death" causing plants can progress with necrotizing myocardial lesions.

Animals , Cattle , Eosinophilia/complications , Plant Poisoning/veterinary , Myocytes, Cardiac/pathology , Sheep , Troponin , Immunohistochemistry/veterinary , Death, Sudden/veterinary , Plants, Toxic/poisoning , Heart Injuries/veterinary
Pesqui. vet. bras ; 36(2): 83-89, fev. 2016. tab, graf
Article in Portuguese | LILACS | ID: lil-777396


Amaranthus spp. são plantas nefrotóxicas popularmente conhecidas como "caruru". Em casos de intoxicação por estas plantas, a principal alteração histopatológica está presente no rim, sob forma de nefrose tubular tóxica, porém em alguns casos pode haver alterações cardíacas. Alterações no eletrocardiograma, compatíveis com quadros de hipercalemia, foram descritas em suínos intoxicados por Amaranthus retroflexus e lesões como degeneração e necrose de miócitos cardíacos descritas em suínos intoxicados por A. caudatus e ovinos intoxicados por A. spinosus. Há dúvidas com relação às alterações cardíacas, que, na maioria dos casos, são incipientes, o que pode levar a erros de interpretação. Para a realização do trabalho foram utilizados blocos parafinados oriundos de um surto natural de intoxicação por A. spinosus no sudeste do Brasil. Esse estudo teve como objetivo detectar a presença de alterações regressivas incipientes no miocárdio de ovinos intoxicados por A. spinosus, através da utilização imuno-histoquímica do anticorpo anti-troponina C. Foram utilizados fragmentos de coração de 8 ovinos adultos e 2 fetos, intoxicados naturalmente por A. spinosus. Estes fragmentos foram submetidos à técnica de imuno-histoquímica com a utilização do anticorpo anti-troponina C. Pela avaliação imuno-histoquímica do coração dos oito ovinos adultos observaram-se diversos grupos de miócitos com diminuição significativa ou ausência de imunorreatividade para o anticorpo anti-troponina C; essas áreas correspondiam, em grande parte, aos mesmos grupos de miócitos que apresentavam, pela coloração de Hematoxilina e Eosina (H.E.) alterações que variavam de leve tumefação celular a aumento da eosinofilia, perda de estriação, lise celular e cariólise, ou mais raramente, acompanhadas de infiltrado inflamatório...

Amaranthus spp. are nephrotoxic plants popularly known as "pigweed". In cases of poisoning by these plants, the main histopathological alteration is found in the kidneys as toxic tubular nephrosis; however, in some cases, there may be cardiac changes. ECG changes associated with hyperkalemia have been described in pigs poisoned by Amaranthus retroflexus. Degeneration and necrosis of myocytes have been described in pigs poisoned by A. caudatus and sheep poisoned by A. spinosus. There are doubts regarding cardiac changes, since in most cases they are incipient and don't exhibit inflammatory reaction, which can lead to misinterpretation. For this study, paraffin blocks with tissues from a poisoning outbreak by A. spinosus in southeastern Brazil were used. The objective of the study was to detect the presence of incipient regressive changes in the myocardium of sheep poisoned by A. spinosus using anti-troponin C antibody-based immunohistochemistry. Fragments of hearts from 8 adult sheep and 2 fetuses naturally poisoned by A. spinosus were used. In the immunohistochemistry evaluation of the 8 hearts from the adult sheep there were several groups of myocytes with significant decrease or absence of immunoreactivity for anti-troponin C antibody. In most cases, these same areas on Hematoxylin and Eosin (HE) staining exhibited changes that varied from mild cellular tumefaction to increased eosinophilia, as well as loss of striation, cell lysis and karyolysis, sometimes accompanied by inflammatory infiltrate...

Animals , Amaranthus/toxicity , Hyperkalemia/veterinary , Plant Poisoning/veterinary , Myocytes, Cardiac/pathology , Sheep , Troponin , Immunohistochemistry/veterinary , Renal Insufficiency/veterinary , Death, Sudden/veterinary , Plants, Toxic/poisoning , Heart Injuries/veterinary
Biomédica (Bogotá) ; 34(3): 387-402, July-Sept. 2014. ilus
Article in Spanish | LILACS | ID: lil-726799


Introducción. El factor de transcripción asociado a la microftalmia ( Microphtalmia-Associated Transcription Factor , MITF) regula la expresión de genes específicos, pero no se conoce su expresión y su función a nivel cardiaco. Objetivos. Identificar la expresión del MITF en corazón y en cardiomiocitos aislados de cobayo, describir los cambios morfológicos asociados con su disminución y evaluar los niveles relativos de su expresión en cardiomiocitos aislados en condiciones de preacondicionamiento isquémico. Materiales y métodos. El análisis de la expresión relativa de la isoforma específica de tejido cardiaco ( heart-type MITF, MITF-H), se determinó mediante reacción en cadena de la polimerasa (PCR) en tiempo real semicuantitativa, secuenciación y Western blot . La disminución del ARNm del MITF se indujo con un ARN pequeño de interferencia ( short hairpin RNA interference , shRNAi) específico. El tamaño, el diámetro y el número de fibras musculares se evaluaron por observación directa con microscopía de luz. Resultados. Se amplificó un fragmento de 281 pb de ADNc; el análisis de la secuencia confirmó la identidad del exón 1 y la isoforma H del MITF. La interferencia del ARNm del MITF se asoció con un mayor índice cardiaco (peso corazón/peso corporal: 5,46 x 10 -3 Vs. 4,6 x 10 -3 ) y un incremento del diámetro de las fibras cardiacas (50,2±16 µm Vs. 38,7±14,7 µm; p<0,05, n=150). En los cardiomiocitos aislados en condiciones de preacondicionamiento isquémico, se observó una expresión relativa del MITF-H mayor que en los miocitos en normoxia y expuestos a lesión por isquemia simulada (80 y 100 veces más, n=5, p<0,05, n=3). Conclusión. Los resultados sugieren que el MITF-H podría estar involucrado en la hipertrofia, la respuesta al estrés por isquemia y la supervivencia de cardiomiocitos de cobayo.

Introduction: The microphthalmia -associated transcription factor ( MITF ) regulates the expression of specific genes and its cardiac expression and function is not known. Objectives: To identify the expression of MITF in hearts and isolated cardiomyocytes from Guinea pigs, to describe morphological changes associated with mRNA interference of MITF and to evaluate their relative changes in expression in isolated cardiomyocytes under ischemic preconditioning. Materials and methods: The cardiac specific isoform, MITF-H, and relative expression level analysis, was determined by semi-quantitative real time PCR, sequencing and Western blotting. Reduction of mRNA-MITF-H was induced by transduction of specific-MITF-shRNAi interference. The cardiac morphological changes, diameter and number of cardiac fibers were evaluated by direct observation and light microscopy. Results: A cDNA fragment of 281 bp was amplified from heart and isolated ventricular cardiac myocytes. Sequence analysis confirmed the identity of the isoform MITF-H, exon 1. The MITF silencing was associated with an increase in cardiac index (heart weight/body weight vs . 5.46 x 10 -3 vs 4.6 x 10 -3 ) and higher diameter of cardiac fibers (50.2±16 µ m vs 38,7±14,7 µ m p<0.05, n=150). In isolated cardiac myocytes under ischemic preconditioning we observed a higher relative expression compared with that measured in myocytes exposed to normoxia and simulated ischemia (eighty and one hundred times, p <0.05, n = 5). Conclusion. The results suggest that MITF-H isoform may be involved in Guinea pig cardiac hypertrophy, response to stress by ischemia and cardiomyocytes survival.

Animals , Female , Guinea Pigs , Cardiomyopathy, Hypertrophic/metabolism , Microphthalmia-Associated Transcription Factor/physiology , Myocardium/metabolism , Myocytes, Cardiac/metabolism , Amino Acid Sequence , Base Sequence , Cell Survival , Cells, Cultured , Cardiomyopathy, Hypertrophic/genetics , DNA, Complementary/genetics , Gene Expression Regulation , Ischemic Preconditioning, Myocardial , Molecular Sequence Data , Microphthalmia-Associated Transcription Factor/antagonists & inhibitors , Microphthalmia-Associated Transcription Factor/biosynthesis , Microphthalmia-Associated Transcription Factor/genetics , Myocardial Ischemia/genetics , Myocardial Ischemia/metabolism , Myocytes, Cardiac/pathology , Oxygen/pharmacology , Protein Isoforms/biosynthesis , Protein Isoforms/genetics , Protein Isoforms/physiology , RNA Interference , RNA, Small Interfering/pharmacology , Sequence Alignment , Sequence Homology
Braz. j. med. biol. res ; 47(5): 361-368, 02/05/2014. tab, graf
Article in English | LILACS | ID: lil-709438


Hypertrophy is a major predictor of progressive heart disease and has an adverse prognosis. MicroRNAs (miRNAs) that accumulate during the course of cardiac hypertrophy may participate in the process. However, the nature of any interaction between a hypertrophy-specific signaling pathway and aberrant expression of miRNAs remains unclear. In this study, Spague Dawley male rats were treated with transverse aortic constriction (TAC) surgery to mimic pathological hypertrophy. Hearts were isolated from TAC and sham operated rats (n=5 for each group at 5, 10, 15, and 20 days after surgery) for miRNA microarray assay. The miRNAs dysexpressed during hypertrophy were further analyzed using a combination of bioinformatics algorithms in order to predict possible targets. Increased expression of the target genes identified in diverse signaling pathways was also analyzed. Two sets of miRNAs were identified, showing different expression patterns during hypertrophy. Bioinformatics analysis suggested the miRNAs may regulate multiple hypertrophy-specific signaling pathways by targeting the member genes and the interaction of miRNA and mRNA might form a network that leads to cardiac hypertrophy. In addition, the multifold changes in several miRNAs suggested that upregulation of rno-miR-331*, rno-miR-3596b, rno-miR-3557-5p and downregulation of rno-miR-10a, miR-221, miR-190, miR-451 could be seen as biomarkers of prognosis in clinical therapy of heart failure. This study described, for the first time, a potential mechanism of cardiac hypertrophy involving multiple signaling pathways that control up- and downregulation of miRNAs. It represents a first step in the systematic discovery of miRNA function in cardiovascular hypertrophy.

Animals , Male , Cardiomegaly/genetics , Down-Regulation/genetics , MicroRNAs/metabolism , Myocytes, Cardiac/pathology , Signal Transduction/genetics , Up-Regulation/genetics , Algorithms , Aorta/surgery , Biomarkers , Computational Biology , Constriction, Pathologic/genetics , Disease Models, Animal , Prognosis , Rats, Sprague-Dawley
Braz. j. med. biol. res ; 45(12): 1150-1156, Dec. 2012. ilus, tab
Article in English | LILACS | ID: lil-659639


Angiotensin II (Ang II) plays an important role in cardiomyocyte hypertrophy. The combined effect of hepatocyte growth factor (HGF) and Ang II on cardiomyocytes is unknown. The present study was designed to determine the effect of HGF on cardiomyocyte hypertrophy and to explore the combined effect of HGF and Ang II on cardiomyocyte hypertrophy. Primary cardiomyocytes were isolated from neonatal rat hearts and cultured in vitro. Cells were treated with Ang II (1 µM) alone, HGF (10 ng/mL) alone, and Ang II (1 µM) plus HGF (10 ng/mL) for 24, 48, and 72 h. The amount of [³H]-leucine incorporation was then measured to evaluate protein synthesis. The mRNA levels of β-myosin heavy chain and atrial natriuretic factor were determined by real-time PCR to evaluate the presence of fetal phenotypes of gene expression. The cell size of cardiomyocytes was also studied. Ang II (1 µM) increased cardiomyocyte hypertrophy. Similar to Ang II, treatment with 1 µM HGF promoted cardiomyocyte hypertrophy. Moreover, the combination of 1 µM Ang II and 10 ng/mL HGF clearly induced a combined pro-hypertrophy effect on cardiomyocytes. The present study demonstrates for the first time a novel, combined effect of HGF and Ang II in promoting cardiomyocyte hypertrophy.

Animals , Rats , Angiotensin II/pharmacology , Hepatocyte Growth Factor/pharmacology , Myocytes, Cardiac/drug effects , Animals, Newborn , Cells, Cultured , Dose-Response Relationship, Drug , Hypertrophy/chemically induced , Hypertrophy/pathology , Myocytes, Cardiac/pathology , Rats, Sprague-Dawley , Real-Time Polymerase Chain Reaction , RNA, Messenger/genetics , RNA, Messenger/metabolism
Braz. j. med. biol. res ; 45(11): 1045-1051, Nov. 2012. ilus
Article in English | LILACS | ID: lil-650569


We investigated whether Ca2+/calmodulin-dependent kinase II (CaMKII) and calcineurin (CaN) are involved in myocardial hypertrophy induced by tumor necrosis factor α (TNF-α). The cardiomyocytes of neonatal Wistar rats (1-2 days old) were cultured and stimulated by TNF-α (100 μg/L), and Ca2+ signal transduction was blocked by several antagonists, including BAPTA (4 µM), KN-93 (0.2 µM) and cyclosporin A (CsA, 0.2 µM). Protein content, protein synthesis, cardiomyocyte volumes, [Ca2+]i transients, CaMKIIδB and CaN were evaluated by the Lowry method, [³H]-leucine incorporation, a computerized image analysis system, a Till imaging system, and Western blot analysis, respectively. TNF-α induced a significant increase in protein content in a dose-dependent manner from 10 µg/L (53.56 µg protein/well) to 100 μg/L (72.18 µg protein/well), and in a time-dependent manner from 12 h (37.42 µg protein/well) to 72 h (42.81 µg protein/well). TNF-α (100 μg/L) significantly increased the amplitude of spontaneous [Ca2+]i transients, the total protein content, cell size, and [³H]-leucine incorporation in cultured cardiomyocytes, which was abolished by 4 µM BAPTA, an intracellular Ca2+ chelator. The increases in protein content, cell size and [³H]-leucine incorporation were abolished by 0.2 µM KN-93 or 0.2 µM CsA. TNF-α increased the expression of CaMKIIδB by 35.21% and that of CaN by 22.22% compared to control. These effects were abolished by 4 µM BAPTA, which itself had no effect. These results suggest that TNF-α induces increases in [Ca2+]i, CaMKIIδB and CaN and promotes cardiac hypertrophy. Therefore, we hypothesize that the Ca2+/CaMKII- and CaN-dependent signaling pathways are involved in myocardial hypertrophy induced by TNF-α.

Animals , Rats , Calcineurin/metabolism , /metabolism , Cardiomegaly/metabolism , Myocytes, Cardiac/metabolism , Tumor Necrosis Factor-alpha/pharmacology , Animals, Newborn , Cells, Cultured , Cardiomegaly/chemically induced , Cardiomegaly/pathology , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/pathology , Rats, Wistar , Signal Transduction