Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos

Detalhes bibliográficos
Autor(a) principal: Carneiro Júnior, Miguel Araújo
Data de Publicação: 2013
Tipo de documento: Tese
Idioma: por
Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
Texto Completo: http://repositorio.ufes.br/handle/10/8056
Resumo: Effects of exercise training and detraining on the molecular and mechanical properties of isolated cardiomyocytes from normotensive and hypertensive rats. Introduction. The endurance training induces benefits on cardiac function that are related to cellular and subcellular adaptations. Studies show that endurance training increases the expression of transient intracellular global Ca2+ ([Ca2+]i) regulatory proteins, the [Ca2+]i transient and contractility of isolated cardiomyocytes from the left ventricle of normotensive rats, although detraining reverses these adaptions. However, the effects of endurance training and detraining on these parameters in hypertensive rat hearts, are not known. Aims. To investigate the effects of low-intensity endurance training and detraining on cardiovascular parameters and molecular and mechanical properties of isolated cardiomyocytes from the left ventricle of normotensive and hypertensive rats. Materials and Methods. Male wistar rats [initial weight of 385.3 ± 6.6 g (mean ± standard error of mean) and systolic blood pressure (SBP) of 110.7 ± 0.5 mmHg] and SHR [Spontaneously Hypertensive Rats (initial weight of 357.5 ± 4.1 g and 178.4 ± 1.3 SBP mm Hg)] with 16 weeks of age, were randomly distributed into 8 groups (n = 8): NC8 and HC8 - normotensive and hypertensive controls for 8 weeks; NT8 and HT8 - normotensive and hypertensive trained at 50-60% of maximal exercise capacity on a treadmill for 8 weeks; NC12 and HC12 - normotensive and hypertensive controls for 12 weeks; NDT and HDT - normotensive and hypertensive trained at 50-60% of maximal exercise capacity on a treadmill for 8 weeks and detrained for 4 weeks. The resting heart rate (RHR) and SBP were measured before and after treatments, using a sensor and tail plethysmography, respectively. The total exercise time until fatigue (TTF) was determined by a maximal exercise capacity test. After treatments, the euthanasia of animals was performed by cervical dislocation followed by thoracotomy. The heart was removed, washed and cannulated via the aorta on an infusion system, and the left ventricular cardiomyocytes were isolated using enzymatic digestion (collagenase). To determine the [Ca2+]i transient, isolated cardiomyocytes from the left ventricle were incubated with the Ca2+ fluorescent indicator Fluo-4 acetoxymethyl ester (Fluo-4 AM) and placed inside an experimental chamber mounted on a confocal microscope. The cell contractility was determined using the technique of changing the length of cardiomyocytes using an edge detection system, with the aid of an inverted microscope. For both experiments, we used field electrical stimulation (20 V, 1 Hz, ~ 25 ° C). The expression of [Ca2+]i regulatory proteins of the left ventricle was measured by 21 Western Blot, and the markers of pathologic cardiac hypertrophy by real-time polymerase chain reaction (RT-PCR). Results. Low-intensity endurance training augmented the TTF (NC8, 11.4 ± 1.5 min vs. NT8, 22.5 ± 1.4 min; HC8, 11.7 ± 1.4 min vs. HT8, 24.5 ± 1.3 min; P ≤ 0.05), reduced RHR (NT8initial, 340 ± 8 bpm vs. NT8final, 322 ± 10 bpm; HT8initial, 369±8 bpm vs. HT8final, 344 ± 10 bpm; P ≤ 0.05), and SBP in SHR animals (HC8, 178 ± 3 mmHg vs. HT8, 161 ± 4 mmHg; P ≤ 0.05). HC8 rats showed a slower [Ca2+]i transient (Tpeak, 83.7 ± 1.8 ms vs. 71.7 ± 2.4 ms; T50%decay, 284.0 ± 4.3 ms vs. 264.0 ± 4.1 ms; P<0.05) and cell contractility (Vshortening, 86.1 ± 6.7 µm/s vs. 118.6 ± 6.7 µm/s; Vrelengthening, 57.5 ± 7.4 µm/s vs. 101.3 ± 7.4 µm/s; P ≤ 0.05), and higher expression of ANF (300%; P ≤ 0.05), skeletal α-actin (250%; P ≤ 0.05) and a decreased α/β-MHC ratio (70%; P ≤ 0.05) compared to NC8. Exercise training increased [Ca2+]i transient (NC8, 2.39 ± 0.06 F/F0 vs. NT8, 2.72 ± 0.06 F/F0; HC8, 2.28 ± 0.05 F/F0 vs. HT8, 2.82 ± 0.05 F/F0; P ≤ 0.05), cell contractility (NC8, 7.4 ± 0.3 % vs. NT8, 8.4 ± 0.3 %; HC8, 6.8 ± 0.3 % vs. HT8, 7.8 ± 0.3 %; P ≤ 0.05), and normalized the expression of ANF, skeletal α-actin, and the α/βMHC ratio in HT8 rats. Furthermore, augmented the expression of sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) (NC8, 0.93 ± 0.15 vs. NT8, 1.49 ± 0.14; HC8, 0.83 ± 0.13 vs. HT8, 1.32 ± 0.14; P<0.05), phosphorylation of phospholamban at serine 16 (PLBser16) (NC8, 0.89 ± 0.18 vs. NT8, 1.23 ± 0.17; HC8, 0.77 ± 0.17 vs. HT8, 1.32 ± 0.16; P<0.05), and reduced the ratio total phospholamban (PLBt)/SERCA2a (NC8, 1.21 ± 0.19 vs. NT8, 0.50 ± 0.21; HC8, 1.38 ± 0.17 vs. HT8, 0.66 ± 0.21; P<0.05) in the left ventricle of trained animals. However, all these adaptations returned to sedentary values within 4 weeks of detraining in both SHR and normotensive animals. Conclusion. The low-intensity endurance training induces beneficial adaptations on the molecular and mechanical properties of isolated cardiomyocytes from the left ventricle of normotensive and hypertensive rats. Detraining for a period of 4 weeks, reversed all these benefits.
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spelling Mill, José GeraldoCarneiro Júnior, Miguel AraújoOliveira , Edilamar Menezes deNascimento, José Hamilton MatheusPrímola-Gomes, Thales NicolauStefanon, Ivanita2018-08-01T22:59:19Z2018-08-012018-08-01T22:59:19Z2013-06-14Effects of exercise training and detraining on the molecular and mechanical properties of isolated cardiomyocytes from normotensive and hypertensive rats. Introduction. The endurance training induces benefits on cardiac function that are related to cellular and subcellular adaptations. Studies show that endurance training increases the expression of transient intracellular global Ca2+ ([Ca2+]i) regulatory proteins, the [Ca2+]i transient and contractility of isolated cardiomyocytes from the left ventricle of normotensive rats, although detraining reverses these adaptions. However, the effects of endurance training and detraining on these parameters in hypertensive rat hearts, are not known. Aims. To investigate the effects of low-intensity endurance training and detraining on cardiovascular parameters and molecular and mechanical properties of isolated cardiomyocytes from the left ventricle of normotensive and hypertensive rats. Materials and Methods. Male wistar rats [initial weight of 385.3 ± 6.6 g (mean ± standard error of mean) and systolic blood pressure (SBP) of 110.7 ± 0.5 mmHg] and SHR [Spontaneously Hypertensive Rats (initial weight of 357.5 ± 4.1 g and 178.4 ± 1.3 SBP mm Hg)] with 16 weeks of age, were randomly distributed into 8 groups (n = 8): NC8 and HC8 - normotensive and hypertensive controls for 8 weeks; NT8 and HT8 - normotensive and hypertensive trained at 50-60% of maximal exercise capacity on a treadmill for 8 weeks; NC12 and HC12 - normotensive and hypertensive controls for 12 weeks; NDT and HDT - normotensive and hypertensive trained at 50-60% of maximal exercise capacity on a treadmill for 8 weeks and detrained for 4 weeks. The resting heart rate (RHR) and SBP were measured before and after treatments, using a sensor and tail plethysmography, respectively. The total exercise time until fatigue (TTF) was determined by a maximal exercise capacity test. After treatments, the euthanasia of animals was performed by cervical dislocation followed by thoracotomy. The heart was removed, washed and cannulated via the aorta on an infusion system, and the left ventricular cardiomyocytes were isolated using enzymatic digestion (collagenase). To determine the [Ca2+]i transient, isolated cardiomyocytes from the left ventricle were incubated with the Ca2+ fluorescent indicator Fluo-4 acetoxymethyl ester (Fluo-4 AM) and placed inside an experimental chamber mounted on a confocal microscope. The cell contractility was determined using the technique of changing the length of cardiomyocytes using an edge detection system, with the aid of an inverted microscope. For both experiments, we used field electrical stimulation (20 V, 1 Hz, ~ 25 ° C). The expression of [Ca2+]i regulatory proteins of the left ventricle was measured by 21 Western Blot, and the markers of pathologic cardiac hypertrophy by real-time polymerase chain reaction (RT-PCR). Results. Low-intensity endurance training augmented the TTF (NC8, 11.4 ± 1.5 min vs. NT8, 22.5 ± 1.4 min; HC8, 11.7 ± 1.4 min vs. HT8, 24.5 ± 1.3 min; P ≤ 0.05), reduced RHR (NT8initial, 340 ± 8 bpm vs. NT8final, 322 ± 10 bpm; HT8initial, 369±8 bpm vs. HT8final, 344 ± 10 bpm; P ≤ 0.05), and SBP in SHR animals (HC8, 178 ± 3 mmHg vs. HT8, 161 ± 4 mmHg; P ≤ 0.05). HC8 rats showed a slower [Ca2+]i transient (Tpeak, 83.7 ± 1.8 ms vs. 71.7 ± 2.4 ms; T50%decay, 284.0 ± 4.3 ms vs. 264.0 ± 4.1 ms; P<0.05) and cell contractility (Vshortening, 86.1 ± 6.7 µm/s vs. 118.6 ± 6.7 µm/s; Vrelengthening, 57.5 ± 7.4 µm/s vs. 101.3 ± 7.4 µm/s; P ≤ 0.05), and higher expression of ANF (300%; P ≤ 0.05), skeletal α-actin (250%; P ≤ 0.05) and a decreased α/β-MHC ratio (70%; P ≤ 0.05) compared to NC8. Exercise training increased [Ca2+]i transient (NC8, 2.39 ± 0.06 F/F0 vs. NT8, 2.72 ± 0.06 F/F0; HC8, 2.28 ± 0.05 F/F0 vs. HT8, 2.82 ± 0.05 F/F0; P ≤ 0.05), cell contractility (NC8, 7.4 ± 0.3 % vs. NT8, 8.4 ± 0.3 %; HC8, 6.8 ± 0.3 % vs. HT8, 7.8 ± 0.3 %; P ≤ 0.05), and normalized the expression of ANF, skeletal α-actin, and the α/βMHC ratio in HT8 rats. Furthermore, augmented the expression of sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) (NC8, 0.93 ± 0.15 vs. NT8, 1.49 ± 0.14; HC8, 0.83 ± 0.13 vs. HT8, 1.32 ± 0.14; P<0.05), phosphorylation of phospholamban at serine 16 (PLBser16) (NC8, 0.89 ± 0.18 vs. NT8, 1.23 ± 0.17; HC8, 0.77 ± 0.17 vs. HT8, 1.32 ± 0.16; P<0.05), and reduced the ratio total phospholamban (PLBt)/SERCA2a (NC8, 1.21 ± 0.19 vs. NT8, 0.50 ± 0.21; HC8, 1.38 ± 0.17 vs. HT8, 0.66 ± 0.21; P<0.05) in the left ventricle of trained animals. However, all these adaptations returned to sedentary values within 4 weeks of detraining in both SHR and normotensive animals. Conclusion. The low-intensity endurance training induces beneficial adaptations on the molecular and mechanical properties of isolated cardiomyocytes from the left ventricle of normotensive and hypertensive rats. Detraining for a period of 4 weeks, reversed all these benefits.Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos. Introdução. O treinamento físico aeróbio provoca benefícios sobre a função cardíaca que estão relacionados a adaptações celulares e subcelulares. Estudos mostram que o treinamento físico aeróbio aumenta a expressão de proteínas reguladoras do transiente intracelular global de Ca2+([Ca2+]i), o transiente de [Ca2+]i e a contratilidade de cardiomiócitos isolados do ventrículo esquerdo de ratos normotensos, embora o destreinamento reverta essas adaptações. Todavia, os efeitos do treinamento físico e do destreinamento sobre esses parâmetros em corações de ratos hipertensos, não são conhecidos. Objetivos. Investigar os efeitos do treinamento físico aeróbio de baixa intensidade e do destreinamento sobre parâmetros cardiovasculares e sobre propriedades moleculares e mecânicas de cardiomiócitos isolados do ventrículo esquerdo de ratos normotensos e hipertensos. Materiais e Métodos. Ratos Wistar [peso inicial de 385,3 ± 6,6 g (média ± erro padrão da média) e pressão arterial sistólica (PAS) de 110,7 ± 0,5 mmHg] e SHR [Spontaneously Hypertensive Rats (peso inicial de 357,5 ± 4,1 g e PAS de 178,4 ± 1,3 mmHg)] com 16 semanas de idade, foram distribuídos aleatoriamente em 8 grupos (n=8): NC8 e HC8 normotensos e hipertensos controles por 8 semanas; NT8 e HT8 normotensos e hipertensos treinados a 50-60% da velocidade máxima de corrida em esteira rolante por 8 semanas; NC12 e HC12 normotensos e hipertensos controles por 12 semanas; NDT e HDT normotensos e hipertensos treinados a 50-60% da velocidade máxima de corrida em esteira rolante por 8 semanas e destreinados por 4 semanas. A frequência cardíaca de repouso (FCR) e a PAS foram determinadas antes e após os tratamentos, através de um sensor e pletismografia de cauda, respectivamente. O tempo total de exercício até a fadiga (TTF) foi determinado através de um teste de capacidade máxima para o exercício. Após os tratamentos, a eutanásia dos animais foi realizada através de deslocamento cervical, seguida de toracotomia. O coração foi removido, lavado e canulado através da artéria aorta em um sistema de perfusão, sendo que os cardiomiócitos do ventrículo esquerdo foram isolados através de digestão enzimática (colagenase). Para a determinação do transiente de [Ca2+]i, os cardiomiócitos isolados do ventrículo esquerdo foram incubados com o indicador fluorescente de Ca2+ Fluo-4 acetoximetil-ester (Fluo-4 AM) e colocados dentro de uma câmara experimental montada em um microscópio confocal. A contratilidade celular foi determinada através da técnica de alteração do comprimento dos cardiomiócitos, usando-se um sistema de detecção de bordas, com o auxílio de um microscópio invertido. Para ambos os 18 experimentos, utilizou-se estimulação elétrica de campo (20 V; 1 Hz; ~ 25ºC). A expressão das proteínas reguladoras do transiente de [Ca2+]i do ventrículo esquerdo foi realizada através de Western Blot, e a expressão dos marcadores de hipertrofia cardíaca patológica através de reação em cadeia da polimerase em tempo real (RT-PCR). Resultados. O treinamento físico aeróbio de baixa intensidade aumentou o TTF (NC8, 11,4 ± 1,5 vs. NT8, 22,5 ± 1,4; HC8, 11,7 ± 1.4 vs. HT8, 24,5 ± 1.3 min; P ≤ 0.05), diminuiu a FCR (NT8inicial, 340 ± 8 vs. NT8final, 322 ± 10; HT8inicial, 369 ± 8 vs. HT8final, 344 ± 10 bpm; P ≤ 0.05), e diminuiu a PAS nos animais SHR (HC8, 178,0 ± 3,2 vs. HT8, 161,2 ± 3,6 mmHg; P ≤ 0,05). Os animais do grupo HC8 apresentaram lentificação do transiente de [Ca2+]i (TPico, 83,7 ± 1,8 vs. 71,7 ± 2,4; T50%Decaimento, 284,0 ± 4,3 vs. 264,0 ± 4,1 ms; P ≤ 0.05) e da contratilidade celular (VContração, 86,1 ± 6,7 vs. 118,6 ± 6,7; VRelaxamento, 57,5 ± 7,4 vs. 101,3 ± 7,4 μm/s; P ≤ 0,05); aumento na expressão do fator natriurético atrial (FNA) (300%; P ≤ 0,05), α-actina esquelética (250%; P ≤ 0,05) e uma diminuição na razão α/β-miosina de cadeia pesada (MCP) (70%; P ≤ 0,05), comparados aos animais do grupo NC8. O programa de corrida aumentou o transiente de [Ca2+]i (NC8, 2,39 ± 0,06 vs. NT8, 2,72 ± 0, 06; HC8, 2,28 ± 0,05 vs. HT8, 2,82 ± 0,05 F/F0; P ≤ 0,05), a contratilidade celular (NC8, 7,4 ± 0,3 vs. NT8, 8,4 ± 0,3; HC8, 6,8 ± 0,3 vs. HT8, 7,8 ± 0,3 % do comprimento celular de repouso; P ≤ 0,05) e normalizou a expressão do FNA, α-actina esquelética, e a razão α/β-MCP no ventrículo esquerdo dos animais do grupo HT8. Além disso, aumentou a expressão da Ca2+ ATPase do retículo sarcoplasmático (SERCA2a) (NC8, 0,93 ± 0,15 vs. NT8, 1,49 ± 0,14; HC8, 0,83 ± 0,13 vs. HT8, 1,32 ± 0,14; P ≤ 0,05), a fosforilação da fosfolambam no resíduo de serina 16 (FLBser16) (NC8, 0,89 ± 0,18 vs. NT8, 1,23 ± 0,17; HC8, 0,77 ± 0,17 vs. HT8, 1,32 ± 0,16; P ≤ 0.05), e diminuiu a razão fosfolambam total (FLBt)/SERCA2a (NC8, 1,21 ± 0,19 vs. NT8, 0,50 ± 0,21; HC8, 1,38 ± 0,17 vs. HT8, 0,66 ± 0.21; P ≤ 0,05) no ventrículo esquerdo dos animais treinados. Entretanto, todas essas adaptações retornaram aos valores iniciais após 4 semanas de destreinamento, tanto nos animais normotensos quanto nos hipertensos. Conclusão. O treinamento físico aeróbio de baixa intensidade provocou adaptações benéficas sobre as propriedades moleculares e mecânicas de cardiomiócitos isolados do ventrículo esquerdo de ratos normotensos e hipertensos. O destreinamento pelo período de 4 semanas, reverteu todos esses benefícios.TextCARNEIRO JUNIOR, Miguel Araújo. Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos. 2018. Tese (Doutorado em Ciências Fisiológicas) - Universidade Federal do Espírito Santo, Centro de Ciências da Saúde, Vitória, 2013.http://repositorio.ufes.br/handle/10/8056porUniversidade Federal do Espírito SantoDoutorado em Ciências FisiológicasPrograma de Pós-Graduação em Ciências FisiológicasUFESBRCentro de Ciências da SaúdePhysical ActivityInactivityHypertensionCardiomyocyteCalcium transientHypertrophy molecular markersAtividade físicaInatividadeHipertensãoCardiomiócitoTransiente de cálcioMarcadores moleculares de hipertrofiaFisiologia612Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensosEffects of exercise training and detraining on the molecular and mechanical properties of isolated cardiomyocytes from normotensive and hypertensive ratsinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)instname:Universidade Federal do Espírito Santo (UFES)instacron:UFESORIGINALTese Miguel Araujo Carneiro Júnior.pdfapplication/pdf3030441http://repositorio.ufes.br/bitstreams/ae6e2d3c-208f-4a61-b467-9118bf133f1d/download834133a3c13a49747315f8d42ddcd782MD5110/80562024-07-16 17:09:57.482oai:repositorio.ufes.br:10/8056http://repositorio.ufes.brRepositório InstitucionalPUBhttp://repositorio.ufes.br/oai/requestopendoar:21082024-10-15T17:55:30.519734Repositório Institucional da Universidade Federal do Espírito Santo (riUfes) - Universidade Federal do Espírito Santo (UFES)false
dc.title.none.fl_str_mv Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos
dc.title.alternative.none.fl_str_mv Effects of exercise training and detraining on the molecular and mechanical properties of isolated cardiomyocytes from normotensive and hypertensive rats
title Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos
spellingShingle Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos
Carneiro Júnior, Miguel Araújo
Physical Activity
Inactivity
Hypertension
Cardiomyocyte
Calcium transient
Hypertrophy molecular markers
Atividade física
Inatividade
Hipertensão
Cardiomiócito
Transiente de cálcio
Marcadores moleculares de hipertrofia
Fisiologia
612
title_short Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos
title_full Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos
title_fullStr Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos
title_full_unstemmed Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos
title_sort Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos
author Carneiro Júnior, Miguel Araújo
author_facet Carneiro Júnior, Miguel Araújo
author_role author
dc.contributor.advisor1.fl_str_mv Mill, José Geraldo
dc.contributor.author.fl_str_mv Carneiro Júnior, Miguel Araújo
dc.contributor.referee1.fl_str_mv Oliveira , Edilamar Menezes de
dc.contributor.referee2.fl_str_mv Nascimento, José Hamilton Matheus
dc.contributor.referee3.fl_str_mv Prímola-Gomes, Thales Nicolau
dc.contributor.referee4.fl_str_mv Stefanon, Ivanita
contributor_str_mv Mill, José Geraldo
Oliveira , Edilamar Menezes de
Nascimento, José Hamilton Matheus
Prímola-Gomes, Thales Nicolau
Stefanon, Ivanita
dc.subject.eng.fl_str_mv Physical Activity
Inactivity
Hypertension
Cardiomyocyte
Calcium transient
Hypertrophy molecular markers
topic Physical Activity
Inactivity
Hypertension
Cardiomyocyte
Calcium transient
Hypertrophy molecular markers
Atividade física
Inatividade
Hipertensão
Cardiomiócito
Transiente de cálcio
Marcadores moleculares de hipertrofia
Fisiologia
612
dc.subject.por.fl_str_mv Atividade física
Inatividade
Hipertensão
Cardiomiócito
Transiente de cálcio
Marcadores moleculares de hipertrofia
dc.subject.cnpq.fl_str_mv Fisiologia
dc.subject.udc.none.fl_str_mv 612
description Effects of exercise training and detraining on the molecular and mechanical properties of isolated cardiomyocytes from normotensive and hypertensive rats. Introduction. The endurance training induces benefits on cardiac function that are related to cellular and subcellular adaptations. Studies show that endurance training increases the expression of transient intracellular global Ca2+ ([Ca2+]i) regulatory proteins, the [Ca2+]i transient and contractility of isolated cardiomyocytes from the left ventricle of normotensive rats, although detraining reverses these adaptions. However, the effects of endurance training and detraining on these parameters in hypertensive rat hearts, are not known. Aims. To investigate the effects of low-intensity endurance training and detraining on cardiovascular parameters and molecular and mechanical properties of isolated cardiomyocytes from the left ventricle of normotensive and hypertensive rats. Materials and Methods. Male wistar rats [initial weight of 385.3 ± 6.6 g (mean ± standard error of mean) and systolic blood pressure (SBP) of 110.7 ± 0.5 mmHg] and SHR [Spontaneously Hypertensive Rats (initial weight of 357.5 ± 4.1 g and 178.4 ± 1.3 SBP mm Hg)] with 16 weeks of age, were randomly distributed into 8 groups (n = 8): NC8 and HC8 - normotensive and hypertensive controls for 8 weeks; NT8 and HT8 - normotensive and hypertensive trained at 50-60% of maximal exercise capacity on a treadmill for 8 weeks; NC12 and HC12 - normotensive and hypertensive controls for 12 weeks; NDT and HDT - normotensive and hypertensive trained at 50-60% of maximal exercise capacity on a treadmill for 8 weeks and detrained for 4 weeks. The resting heart rate (RHR) and SBP were measured before and after treatments, using a sensor and tail plethysmography, respectively. The total exercise time until fatigue (TTF) was determined by a maximal exercise capacity test. After treatments, the euthanasia of animals was performed by cervical dislocation followed by thoracotomy. The heart was removed, washed and cannulated via the aorta on an infusion system, and the left ventricular cardiomyocytes were isolated using enzymatic digestion (collagenase). To determine the [Ca2+]i transient, isolated cardiomyocytes from the left ventricle were incubated with the Ca2+ fluorescent indicator Fluo-4 acetoxymethyl ester (Fluo-4 AM) and placed inside an experimental chamber mounted on a confocal microscope. The cell contractility was determined using the technique of changing the length of cardiomyocytes using an edge detection system, with the aid of an inverted microscope. For both experiments, we used field electrical stimulation (20 V, 1 Hz, ~ 25 ° C). The expression of [Ca2+]i regulatory proteins of the left ventricle was measured by 21 Western Blot, and the markers of pathologic cardiac hypertrophy by real-time polymerase chain reaction (RT-PCR). Results. Low-intensity endurance training augmented the TTF (NC8, 11.4 ± 1.5 min vs. NT8, 22.5 ± 1.4 min; HC8, 11.7 ± 1.4 min vs. HT8, 24.5 ± 1.3 min; P ≤ 0.05), reduced RHR (NT8initial, 340 ± 8 bpm vs. NT8final, 322 ± 10 bpm; HT8initial, 369±8 bpm vs. HT8final, 344 ± 10 bpm; P ≤ 0.05), and SBP in SHR animals (HC8, 178 ± 3 mmHg vs. HT8, 161 ± 4 mmHg; P ≤ 0.05). HC8 rats showed a slower [Ca2+]i transient (Tpeak, 83.7 ± 1.8 ms vs. 71.7 ± 2.4 ms; T50%decay, 284.0 ± 4.3 ms vs. 264.0 ± 4.1 ms; P<0.05) and cell contractility (Vshortening, 86.1 ± 6.7 µm/s vs. 118.6 ± 6.7 µm/s; Vrelengthening, 57.5 ± 7.4 µm/s vs. 101.3 ± 7.4 µm/s; P ≤ 0.05), and higher expression of ANF (300%; P ≤ 0.05), skeletal α-actin (250%; P ≤ 0.05) and a decreased α/β-MHC ratio (70%; P ≤ 0.05) compared to NC8. Exercise training increased [Ca2+]i transient (NC8, 2.39 ± 0.06 F/F0 vs. NT8, 2.72 ± 0.06 F/F0; HC8, 2.28 ± 0.05 F/F0 vs. HT8, 2.82 ± 0.05 F/F0; P ≤ 0.05), cell contractility (NC8, 7.4 ± 0.3 % vs. NT8, 8.4 ± 0.3 %; HC8, 6.8 ± 0.3 % vs. HT8, 7.8 ± 0.3 %; P ≤ 0.05), and normalized the expression of ANF, skeletal α-actin, and the α/βMHC ratio in HT8 rats. Furthermore, augmented the expression of sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) (NC8, 0.93 ± 0.15 vs. NT8, 1.49 ± 0.14; HC8, 0.83 ± 0.13 vs. HT8, 1.32 ± 0.14; P<0.05), phosphorylation of phospholamban at serine 16 (PLBser16) (NC8, 0.89 ± 0.18 vs. NT8, 1.23 ± 0.17; HC8, 0.77 ± 0.17 vs. HT8, 1.32 ± 0.16; P<0.05), and reduced the ratio total phospholamban (PLBt)/SERCA2a (NC8, 1.21 ± 0.19 vs. NT8, 0.50 ± 0.21; HC8, 1.38 ± 0.17 vs. HT8, 0.66 ± 0.21; P<0.05) in the left ventricle of trained animals. However, all these adaptations returned to sedentary values within 4 weeks of detraining in both SHR and normotensive animals. Conclusion. The low-intensity endurance training induces beneficial adaptations on the molecular and mechanical properties of isolated cardiomyocytes from the left ventricle of normotensive and hypertensive rats. Detraining for a period of 4 weeks, reversed all these benefits.
publishDate 2013
dc.date.issued.fl_str_mv 2013-06-14
dc.date.accessioned.fl_str_mv 2018-08-01T22:59:19Z
dc.date.available.fl_str_mv 2018-08-01
2018-08-01T22:59:19Z
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dc.identifier.citation.fl_str_mv CARNEIRO JUNIOR, Miguel Araújo. Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos. 2018. Tese (Doutorado em Ciências Fisiológicas) - Universidade Federal do Espírito Santo, Centro de Ciências da Saúde, Vitória, 2013.
dc.identifier.uri.fl_str_mv http://repositorio.ufes.br/handle/10/8056
identifier_str_mv CARNEIRO JUNIOR, Miguel Araújo. Efeitos do treinamento físico e do destreinamento sobre propriedades moleculares e mecânicas de cardiomiócitos isolados de ratos normotensos e hipertensos. 2018. Tese (Doutorado em Ciências Fisiológicas) - Universidade Federal do Espírito Santo, Centro de Ciências da Saúde, Vitória, 2013.
url http://repositorio.ufes.br/handle/10/8056
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dc.publisher.none.fl_str_mv Universidade Federal do Espírito Santo
Doutorado em Ciências Fisiológicas
dc.publisher.program.fl_str_mv Programa de Pós-Graduação em Ciências Fisiológicas
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dc.publisher.country.fl_str_mv BR
dc.publisher.department.fl_str_mv Centro de Ciências da Saúde
publisher.none.fl_str_mv Universidade Federal do Espírito Santo
Doutorado em Ciências Fisiológicas
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