Browsing by Author "Fonseca, Silvia Carolina Guatimosim"

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    Dysautonomia due to reduced cholinergic neurotransmission causes cardiac remodeling and heart failure.
    (2010) Gomes, Aline Alves Lara; Damasceno, Dênis Derly; Pires, Rita Gomes Wanderley; Gros, Robert; Gomes, Enéas Ricardo de Morais; Gavioli, Mariana; Lima, Ricardo de Freitas; Guimarães, Diogo Aparecido da Silva; Lima, Patrícia Maria d'Almeida; Bueno Júnior, Carlos Roberto; Vasconcelos, Anilton Cesar; Campos, Danilo Roman; Menezes, Cristiane Alves da Silva; Sirvente, Raquel de Assis; Salemi, Vera Maria Cury; Mady, Charles; Caron, Marc G.; Ferreira, Anderson José; Brum, Patricia Chakur; Resende, Rodrigo Ribeiro; Cruz, Jader dos Santos; Gomez, Marcus Vinicius; Prado, Vânia Ferreira; Almeida, Alvair Pinto de; Prado, Marco Antônio Maximo; Fonseca, Silvia Carolina Guatimosim
    Overwhelming evidence supports the importance of the sympathetic nervous system in heart failure. In contrast, much less is known about the role of failing cholinergic neurotransmission in cardiac disease. By using a unique genetically modified mouse line with reduced expression of the vesicular acetylcholine transporter (VAChT) and consequently decreased release of acetylcholine, we investigated the consequences of altered cholinergic tone for cardiac function. M-mode echocardiography, hemodynamic experiments, analysis of isolated perfused hearts, and measurements of cardiomyocyte contraction indicated that VAChT mutant mice have decreased left ventricle function associated with altered calcium handling. Gene expression was analyzed by quantitative reverse transcriptase PCR and Western blotting, and the results indicated that VAChT mutant mice have profound cardiac remodeling and reactivation of the fetal gene program. This phenotype was attributable to reduced cholinergic tone, since administration of the cholinesterase inhibitor pyridostigmine for 2 weeks reversed the cardiac phenotype in mutant mice. Our findings provide direct evidence that decreased cholinergic neurotransmission and underlying autonomic imbalance cause plastic alterations that contribute to heart dysfunction.
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    Protein restriction after weaning modifies the calcium kinetics and induces cardiomyocyte contractile dysfunction in rats.
    (2013) Penitente, Arlete Rita; Novaes, Rômulo Dias; Chianca Júnior, Deoclécio Alves; Silva, Márcia Ferreira da; Silva, Marcelo Eustáquio; Souza, Aline Maria Arlindo de; Fonseca, Silvia Carolina Guatimosim; Almeida, Pedro William Machado de; Alves, Márcia Netto Magalhães; Felix, Leonardo Bonato; Neves, Clóvis Andrade; Natali, Antônio José
    Protein restriction (PR) is associated with cardiovascular diseases. The purpose of this study was to investigate the effects on single ventricular cardiomyocyte contractile function of a short-term PR after weaning. Male Fischer rats that were 28 days old were randomly divided into a control group (CG, n = 16) and a protein-restricted group (PRG, n = 16). After weaning, CG and PRG animals received isocaloric diets containing 15 and 6% protein, respectively, for 35 days. Biometric parameters were then measured, and the hearts were removed for the analysis of contractile function and calcium transient in isolated cardiomyocytes of the left ventricule (LV), and the quantification of calcium and collagen fibers in LV myocardium. PRG animals had lower body weight (BW) and LV weight (LVW), an increased LVW to BW ratio and a higher proportion of collagen fibers than CG animals. PRG animals exhibited reduced tissue levels of calcium, reduced the length, width and volume of cardiomyocytes and their sarcomere length compared to CG animals. Cardiomyocytes from PRG animals had a lower amplitude of shortening, a slower time to the peak of shortening and a longer time to half-relaxation than those from the CG. Cardiomyocytes from PRG animals also presented a lower peak of calcium transient and a longer calcium transient decay time than CG animals. Taken together, the results indicate that short-term PR after weaning induces a marked structural remodeling of the myocardium parenchyma and stroma that coexists with contractile dysfunctions in single LV cardiomyocytes of rats, which is probably associated with pathological changes of the intracellular calcium kinetics, rather than inadequate available amounts of this mineral in cardiac tissue.