Fator induzível por hipóxia miocárdica, metabolismo da glicose, estrutura e função ventricular durante o processo de evolução da remodelação cardíaca: comportamento e associação
Carregando...
Arquivos
Data
2018-02-28
Autores
Sant'Ana, Paula Grippa
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Introdução - A estenose aórtica supravalvar (EAo) experimental é utilizada para induzir a remodelação cardíaca (RC) patológica; esse modelo provoca, inicialmente disfunção diastólica e, posteriormente, distúrbio sistólico e insuficiência cardíaca (IC). Diferentes fatores podem contribuir para essa alteração funcional como, déficit de oxigênio (O2). O principal regulador da homeostase do O2 é o fator induzível por hipóxia-1α (HIF-1α) que na condição normóxia é sintetizado e degradado. No coração hipertrofiado, isquêmico, o HIF-1α torna-se estável e regula a transcrição de vários genes que aumentam a disponibilidade de O2. Além disso, aumenta a expressão das proteínas da via da glicose, com a finalidade de aumentar a oferta de energia. Embora, existam trabalhos que mostraram alteração do HIF-1 α, metabolismo de glicose e função cardíaca, não encontramos na literatura pesquisas que analisaram o comportamento e a associação do HIF-1α com o metabolismo glicídico, estrutura e função ventricular durante a evolução da remodelação por EAo. Objetivos gerais – Analisar durante o processo de evolução da RC o comportamento do HIF-1α, metabolismo da glicose, estrutura e função ventricular e a associação entre o HIF-1α e estas variáveis. Material e métodos – Foram utilizados dois grupos de ratos Wistar: controle operado (Sham, n=48) e EAo (n=48): os animais foram submetidos a cirurgia e no grupo EAo foi implantado um clipe de 0,60 mm de diâmetro na raiz da aorta. Os ratos foram avaliados nos momentos de 2, 6, 18 semanas após cirurgia e na fase de IC grave. Os subgrupos Sham2, 6, 18, IC, e EAo2, 6, 18, IC foram constituídos por 12 animais. A estrutura e função cardíaca foram analisadas por ecocardiograma. A hipertrofia cardíaca foi também avaliada, post mortem. No miocárdico foram analisadas a expressão do HIF-1α, das proteínas da glicólise [hexoquinaseII (HKII), fosfofrutoquinase-2 (PFK-2)], via aeróbica [piruvato desidrogenase (PDH)], via anaeróbica [lactato desidrogenase (LDH)], da captação de glicose [transportador de glicose 1 e 4 (GLUT1 e GLUT4), do receptor de insulina (IR), do fosfatoinositol-3- quinase (PI3K) e quinase ativada pela adenosina monofosfato (AMPK)] pela técnica de Western Blot. As atividades das HK, PK, LDH, citrato sintase (CS) e a concentração de lactato foram analisadas por ensaio enzimático. Análise estatística foi realizada pela técnica de variância (ANOVA) para o esquema fatorial 2x4, complementada com teste de comparações múltiplas de Tukey (paramétrico) e Dunn (não paramétrico). Aassociação entre o HIF-1α e os conjuntos de variáveis foi estudada por meio da correlação canônica. Todas as conclusões estatísticas foram discutidas ao nível de 5% de significância. Resultados: Os principais achados significativos deste estudo foram: a) acentuação da hipertrofia ventricular esquerda durante a evolução da RC, alteração precoce na função diastólica e severa disfunção sistólica e diastólica na fase de IC grave; b) aumento do HIF-1α no início da RC e agravamento na fase de IC ; c) alteração precoce no metabolismo da glicose, com acentuação da via glicolítica e desvio para a via anaeróbica a partir da 6ª semana de EAo; d) associação significativa entre o HIF-1α e alteração estrutural, função diastólica e metabolismo da glicose. Conclusões: a) há aumento do HIF-1α e reprogramação do metabolismo da glicose, hipertrofia e disfunção diastólica a partir da 2ª semana de EAo; b) durante a evolução da RC ocorre elevação do HIF-1α, das proteínas da captação de glicose e via glicolítica com desvio para via anaeróbia; c) há associação canônica entre o conjunto do HIF-1α com o agrupamento das variáveis relacionadas com a via da glicose, estrutura e função diastólica cardíaca.
Introduction - The experimental supravalvar aortic stenosis (AS) is used to induce pathological cardiac remodeling (CR); this model causes, initially, diastolic dysfunction and, later, systolic disorder and heart failure (HF). Different factors may contribute to these cardiac functional alterations, such as oxygen (O2) deficiency. The main regulator of O2 is hypoxia-inducible transcription factor (HIF-1α) that in normoxia condition is synthesized and degraded. In the hypertrophied, ischemic heart, HIF-1α becomes stable and regulates the transcription of several genes that increase O2 availability. In addition, it increases the expression of the glucose pathway proteins, in order to increase energy supply. Although there are studies that have shown alterations in HIF-1α, glucose metabolism and cardiac function, we have not found in the literature studies that investigated the behavior and association of HIF-1α with glucose metabolism, ventricular structure and function during the evolution of CR by AS.Objective - To analyze, during the course of CR evolution, the behavior of HIF-1α, glucose metabolism, ventricular structure and function, and the association between HIF-1α and these variables. Material and methods - Two groups of rats were studied: operated control (Sham, n=48) and supravalvar aortic stenosis (AS, n=48): the animals underwent surgery and in the AS group a clip of 0.60 mm diameter was placed at the aorta’s root. The rats were evaluated at 2, 6, 18 weeks after surgery and at the severe HF phase. The subgroups Sham2, 6, 18, HF and AS2, 6, 18, HF were composed of 12 animals/group. Cardiac structure and function were analyzed by echocardiogram. Cardiac hypertrophy was also evaluated, post mortem. The expression of myocardial: HIF-1α; glycolytic proteins [hexokinase II (HKII), phosphofructokinase-2 (PFK-2), pyruvate dehydrogenase (PDH) and lactate dehydrogenase (LDH)]; glucose uptake proteins [intracellular glucose transporters (GLUT1 and GLUT4)]; insulin receptor (IR); phosphateinositol-3-kinase (PI3K) and adenosine monophosphate-activated protein kinase (AMPK) were analyzed by Western Blot. The activities of HKII, pyruvate kinase (PK), LDH and citrate synthase (CS) were also analyzed by enzymatic assays, and lactate concentration was also measured. Statistical analysis was performed by analysis of variance (ANOVA) technique for the 2x4 factorial scheme, complemented with Tukey's (parametric) or Dunn’s (non-parametric) multiple comparisons test. The association between HIF-1α and the sets of variables was analyzed through canonical correlation. All statistical conclusions were discussed at the 5% significance level. Results - The main significant findings of this study were: a) accentuation of left ventricular hypertrophy during the course of CR, early alteration in diastolic function and severe systolic and diastolic dysfunction in the phase of severe heart failure; b) increased HIF-1α at the onset of CR and worsening in severe HF phase; c) early changes in glucose metabolism, with enhancement of the glycolytic pathway and switch to the anaerobic pathway from the 6th week of AS; d) significant association between HIF-1α and cardiac structural alteration, diastolic function and glucose metabolism. Conclusions - a) there is an increase in HIF-1α, reprogramming of glucose metabolism, hypertrophy and diastolic dysfunction from the 2 nd week of AS; b) during the evolution of CR, there is an elevation in HIF-1α, in glucose uptake and glycolytic pathway proteins with switch to the anaerobic pathway; c) there is an association between HIF-1α and the grouping of variables related to the glucose pathway, cardiac structure and diastolic function.
Introduction - The experimental supravalvar aortic stenosis (AS) is used to induce pathological cardiac remodeling (CR); this model causes, initially, diastolic dysfunction and, later, systolic disorder and heart failure (HF). Different factors may contribute to these cardiac functional alterations, such as oxygen (O2) deficiency. The main regulator of O2 is hypoxia-inducible transcription factor (HIF-1α) that in normoxia condition is synthesized and degraded. In the hypertrophied, ischemic heart, HIF-1α becomes stable and regulates the transcription of several genes that increase O2 availability. In addition, it increases the expression of the glucose pathway proteins, in order to increase energy supply. Although there are studies that have shown alterations in HIF-1α, glucose metabolism and cardiac function, we have not found in the literature studies that investigated the behavior and association of HIF-1α with glucose metabolism, ventricular structure and function during the evolution of CR by AS.Objective - To analyze, during the course of CR evolution, the behavior of HIF-1α, glucose metabolism, ventricular structure and function, and the association between HIF-1α and these variables. Material and methods - Two groups of rats were studied: operated control (Sham, n=48) and supravalvar aortic stenosis (AS, n=48): the animals underwent surgery and in the AS group a clip of 0.60 mm diameter was placed at the aorta’s root. The rats were evaluated at 2, 6, 18 weeks after surgery and at the severe HF phase. The subgroups Sham2, 6, 18, HF and AS2, 6, 18, HF were composed of 12 animals/group. Cardiac structure and function were analyzed by echocardiogram. Cardiac hypertrophy was also evaluated, post mortem. The expression of myocardial: HIF-1α; glycolytic proteins [hexokinase II (HKII), phosphofructokinase-2 (PFK-2), pyruvate dehydrogenase (PDH) and lactate dehydrogenase (LDH)]; glucose uptake proteins [intracellular glucose transporters (GLUT1 and GLUT4)]; insulin receptor (IR); phosphateinositol-3-kinase (PI3K) and adenosine monophosphate-activated protein kinase (AMPK) were analyzed by Western Blot. The activities of HKII, pyruvate kinase (PK), LDH and citrate synthase (CS) were also analyzed by enzymatic assays, and lactate concentration was also measured. Statistical analysis was performed by analysis of variance (ANOVA) technique for the 2x4 factorial scheme, complemented with Tukey's (parametric) or Dunn’s (non-parametric) multiple comparisons test. The association between HIF-1α and the sets of variables was analyzed through canonical correlation. All statistical conclusions were discussed at the 5% significance level. Results - The main significant findings of this study were: a) accentuation of left ventricular hypertrophy during the course of CR, early alteration in diastolic function and severe systolic and diastolic dysfunction in the phase of severe heart failure; b) increased HIF-1α at the onset of CR and worsening in severe HF phase; c) early changes in glucose metabolism, with enhancement of the glycolytic pathway and switch to the anaerobic pathway from the 6th week of AS; d) significant association between HIF-1α and cardiac structural alteration, diastolic function and glucose metabolism. Conclusions - a) there is an increase in HIF-1α, reprogramming of glucose metabolism, hypertrophy and diastolic dysfunction from the 2 nd week of AS; b) during the evolution of CR, there is an elevation in HIF-1α, in glucose uptake and glycolytic pathway proteins with switch to the anaerobic pathway; c) there is an association between HIF-1α and the grouping of variables related to the glucose pathway, cardiac structure and diastolic function.
Descrição
Palavras-chave
Remodelação cardíaca, HIF-1α, Metabolismo da glicose, Estenose aórtica supravalvar, Ratos, Cardiac remodeling, glucose metabolism, supravalvar aortic stenosis, rats