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1.
Braz. j. med. biol. res ; 50(5): e5742, 2017. tab, graf
Article in English | LILACS | ID: biblio-839290

ABSTRACT

Cardiac remodeling is defined as changes in shape and function of the heart in response to aggression (pressure overload). The sarcoplasmic reticulum calcium ATPase cardiac isoform 2a (SERCA2a) is a known factor that influences function. A wide spectrum of studies report a decrease in SERCA2a in heart failure, but none evaluate it's the role in early isolated diastolic dysfunction in supravalvular aortic stenosis (AoS). Our hypothesis was that SERCA2a participates in such dysfunction. Thirty-day-old male Wistar rats (60-80 g) were divided into AoS and Sham groups, which were submitted to surgery with or without aorta clipping, respectively. After 6 weeks, the animals were submitted to echocardiogram and functional analysis by isolated papillary muscle (IPM) in basal condition, hypoxia, and SERCA2a blockage with cyclopiazonic acid at calcium concentrations of 0.5, 1.5, and 2.5 mM. Western-blot analyses were used for SERCA2a and phospholamban detection. Data analysis was carried out with Student's t-test and ANOVA. AoS enhanced left atrium and E and A wave ratio, with preserved ejection fraction. Basal condition in IPM showed similar increases in developed tension (DT) and resting tension (RT) in AoS, and hypoxia was similar between groups. After cyclopiazonic acid blockage, final DT was equally decreased and RT was similar between groups, but the speed of relaxation was decreased in the AoS group. Western-blot was uniform in all evaluations. The hypothesis was confirmed, since functional parameters regarding SERCA2a were changed in the AoS group.


Subject(s)
Animals , Male , Aortic Stenosis, Supravalvular/complications , Hypertrophy, Left Ventricular/physiopathology , Sarcoplasmic Reticulum Calcium-Transporting ATPases/physiology , Ventricular Dysfunction, Left/physiopathology , Aortic Stenosis, Supravalvular/metabolism , Calcium-Binding Proteins/analysis , Collagen/analysis , Diastole/physiology , Disease Models, Animal , Echocardiography , Heart Ventricles/pathology , Heart Ventricles/physiopathology , Hypertrophy, Left Ventricular/etiology , Hypertrophy, Left Ventricular/metabolism , Hypoxia/metabolism , Hypoxia/physiopathology , Indoles , Myocardial Contraction/physiology , Rats, Wistar , Sarcoplasmic Reticulum Calcium-Transporting ATPases/analysis , Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism , Time Factors , Ventricular Dysfunction, Left/etiology , Ventricular Dysfunction, Left/metabolism , Ventricular Remodeling/physiology
2.
Arq. bras. cardiol ; 90(6): 443-450, jun. 2008. ilus, graf
Article in English, Portuguese | LILACS | ID: lil-485191

ABSTRACT

A hipertrofia ventricular esquerda (HVE) ocorre em reposta à sobrecarga hemodinâmica relatada em várias condições fisiológicas e patológicas. Entretanto, ainda não está completamente elucidado se o estímulo primário para a hipertrofia é o estiramento mecânico do coração, fatores neuro-humorais, ou mesmo a interação de ambos. Esses fatores são traduzidos no interior da célula como alterações bioquímicas que levam à ativação de segundos (citosólicos) e terceiros (nucleares) mensageiros que irão agir no núcleo da célula, regulando a transcrição, e finalmente determinarão a expressão gênica que induza HVE. A HVE é caracterizada por alterações estruturais decorrentes do aumento das dimensões dos cardiomiócitos, da proliferação do tecido conjuntivo intersticial e da rarefação da microcirculação coronariana. Nos últimos anos, o óxido nítrico (•NO) surgiu como um importante regulador do remodelamento cardíaco, especificamente reconhecido como um mediador anti-hipertrófico. Vários estudos têm demonstrado os alvos celulares, as vias de sinalização anti-hipertrófica e o papel funcional do •NO. Portanto, a HVE parece desenvolver-se em decorrência da perda do balanço entre as vias de sinalização pró e anti-hipertróficas. Esses novos conhecimentos sobre as vias de sinalização pró e anti-hipertróficas permitirão desenvolver novas estratégicas no tratamento das HVE patológicas.


The left ventricular hypertrophy (LVH) occurs in response to the hemodynamic overload in some physiological and pathological conditions. However, it has not been completely elucidated whether the primary stimulation for the hypertrophy is the mechanical stretching of the heart, neurohumoral factors, or even the interaction of both. These factors are translated inside the cell as biochemical alterations that lead to the activation of second (cytosolic) and third (nuclear) messengers that will act in the cell nucleus, regulating transcription, and will finally determine the genic expression that induces LVH. The LVH is characterized by structural alterations due to the increase in the cardiomyocyte dimensions, the proliferation of the interstitial connective tissue and the rarefaction of the coronary microcirculation. Recently, nitric oxide (•NO) has appeared as an important regulator of cardiac remodeling, specifically recognized as an anti-hypertrophic mediator. Some studies have demonstrated the cellular targets, the anti-hypertrophic signaling pathways and the functional role of •NO. Thus, the LVH seems to develop as a result of the loss of the balance between the pro and the anti-hypertrophic signaling pathways. This new knowledge about the pro and anti-hypertrophic signaling pathways will allow the development of new strategies in the treatment of pathological LVH.


Subject(s)
Animals , Humans , Hypertrophy, Left Ventricular/etiology , Myocytes, Cardiac/physiology , Nitric Oxide Synthase/physiology , Nitric Oxide/physiology , Endothelial Cells/physiology , Hemodynamics , Hypertension/complications , Hypertrophy, Left Ventricular/metabolism , Hypertrophy, Left Ventricular/physiopathology , Nitric Oxide Synthase/antagonists & inhibitors , Nitric Oxide/biosynthesis , Oxidative Stress , Ventricular Remodeling/physiology
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