RESUMO
Individuals with type 2 diabetes mellitus (T2DM) are at an increased risk for heart failure, yet preventive cardiac care is suboptimal in this population. Pyridoxamine (PM), a vitamin B6 analog, has been shown to exert protective effects in metabolic and cardiovascular diseases. In this study, we aimed to investigate whether PM limits adverse cardiac remodeling and dysfunction in rats who develop T2DM. Male rats received a standard chow diet or Western diet (WD) for 18 weeks to induce prediabetes. One WD group received additional PM (1 g/L) via drinking water. Glucose tolerance was assessed with a 1 h oral glucose tolerance test. Cardiac function was evaluated using echocardiography and hemodynamic measurements. Histology on left ventricular (LV) tissue was performed. Treatment with PM prevented the increase in fasting plasma glucose levels compared to WD-fed rats (p < 0.05). LV cardiac dilation tended to be prevented using PM supplementation. In LV tissue, PM limited an increase in interstitial collagen deposition (p < 0.05) seen in WD-fed rats. PM tended to decrease 3-nitrotyrosine and significantly lowered 4-hydroxynonenal content compared to WD-fed rats. We conclude that PM alleviates interstitial fibrosis and oxidative stress in the hearts of WD-induced prediabetic rats.
Assuntos
Dieta Ocidental , Fibrose , Estresse Oxidativo , Estado Pré-Diabético , Piridoxamina , Animais , Estresse Oxidativo/efeitos dos fármacos , Masculino , Ratos , Estado Pré-Diabético/tratamento farmacológico , Estado Pré-Diabético/metabolismo , Estado Pré-Diabético/etiologia , Piridoxamina/farmacologia , Dieta Ocidental/efeitos adversos , Miocárdio/metabolismo , Miocárdio/patologia , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/tratamento farmacológico , Glicemia/metabolismoRESUMO
Myocardial infarction irreversibly destroys millions of cardiomyocytes in the ventricle, making it the leading cause of heart failure worldwide. Over the past two decades, many progenitor and stem cell types were proposed as the ideal candidate to regenerate the heart after injury. The potential of stem cell therapy has been investigated thoroughly in animal and human studies, aiming at cardiac repair by true tissue replacement, by immune modulation, or by the secretion of paracrine factors that stimulate endogenous repair processes. Despite some successful results in animal models, the outcome from clinical trials remains overall disappointing, largely due to the limited stem cell survival and retention after transplantation. Extensive interest was developed regarding the combinational use of stem cells and various priming strategies to improve the efficacy of regenerative cell therapy. In this review, we provide a critical discussion of the different stem cell types investigated in preclinical and clinical studies in the field of cardiac repair. Moreover, we give an update on the potential of stem cell combinations as well as preconditioning and explore the future promises of these novel regenerative strategies.
Assuntos
Infarto do Miocárdio , Animais , Humanos , Infarto do Miocárdio/terapia , Miócitos Cardíacos , Regeneração , Transplante de Células-Tronco/métodosRESUMO
PURPOSE: Exercise training improves exercise capacity in type 2 diabetes mellitus (T2DM). It remains to be elucidated whether such improvements result from cardiac or peripheral muscular adaptations, and whether these are intensity dependent. METHODS: 27 patients with T2DM [without known cardiovascular disease (CVD)] were randomized to high-intensity interval training (HIIT, n = 15) or moderate-intensity endurance training (MIT, n = 12) for 24 weeks (3 sessions/week). Exercise echocardiography was applied to investigate cardiac output (CO) and oxygen (O2) extraction during exercise, while exercise capacity [([Formula: see text] (mL/kg/min)] was examined via cardiopulmonary exercise testing at baseline and after 12 and 24 weeks of exercise training, respectively. Changes in glycaemic control (HbA1c and glucose tolerance), lipid profile and body composition were also evaluated. RESULTS: 19 patients completed 24 weeks of HIIT (n = 10, 66 ± 11 years) or MIT (n = 9, 61 ± 5 years). HIIT and MIT similarly improved glucose tolerance (pTime = 0.001, pInteraction > 0.05), [Formula: see text] (mL/kg/min) (pTime = 0.001, pInteraction > 0.05), and exercise performance (Wpeak) (pTime < 0.001, pInteraction > 0.05). O2 extraction increased to a greater extent after 24 weeks of MIT (56.5%, p1 = 0.009, pTime = 0.001, pInteraction = 0.007). CO and left ventricular longitudinal strain (LS) during exercise remained unchanged (pTime > 0.05). A reduction in HbA1c was correlated with absolute changes in LS after 12 weeks of MIT (r = - 0.792, p = 0.019, LS at rest) or HIIT (r = - 0.782, p = 0.038, LS at peak exercise). CONCLUSION: In patients with well-controlled T2DM, MIT and HIIT improved exercise capacity, mainly resulting from increments in O2 extraction capacity, rather than changes in cardiac output. In particular, MIT seemed highly effective to generate these peripheral adaptations. TRIAL REGISTRATION: NCT03299790, initially released 09/12/2017.
Assuntos
Diabetes Mellitus Tipo 2 , Treinamento Intervalado de Alta Intensidade , Diabetes Mellitus Tipo 2/terapia , Exercício Físico , Treinamento Intervalado de Alta Intensidade/métodos , Humanos , Oxigênio , Consumo de OxigênioRESUMO
Chronically increased levels of high molecular weight advanced glycation end products (HMW-AGEs) are known to induce cardiovascular dysfunction. Whether an acute increase in HMW-AGE levels affects vascular function remains unknown. In this study, we examined whether acute exposure to HMW-AGEs disturbs aortic vasomotor function. Aortae were obtained from healthy male rats and were acutely pre-treated with HMW-AGEs in organ baths. Aortic relaxation responses to cumulative doses of acetylcholine (ACh), in the presence or absence of superoxide dismutase (SOD), were measured after precontraction with phenylephrine (PE). Furthermore, levels of 3-nitrotyrosine were evaluated on aortic paraffine sections. In our study, we show that acute exposure to HMW-AGEs significantly decreases the aortic relaxation response to ACh. SOD pre-treatment prevents acute HMW-AGEs-induced impairment by limiting superoxide formation. In conclusion, our data demonstrate that acute exposure to HMW-AGEs causes adverse vascular remodelling, characterised by disturbed vasomotor function due to increased oxidative stress. These results create opportunities for future research regarding the acute role of HMW-AGEs in cardiovascular dysfunction.
Assuntos
Aorta , Proteínas Glicadas , Masculino , Ratos , Animais , Aorta/metabolismo , Estresse Oxidativo , Produtos Finais de Glicação Avançada/metabolismo , Superóxido Dismutase/metabolismo , Endotélio Vascular/metabolismo , Acetilcolina/farmacologia , Acetilcolina/metabolismo , VasodilataçãoRESUMO
BACKGROUND AND PURPOSE: The development of myocardial fibrosis is a major complication of Type 2 diabetes mellitus (T2DM), impairing myocardial deformation and, therefore, cardiac performance. It remains to be established whether abnormalities in longitudinal strain (LS) exaggerate or only occur in well-controlled T2DM, when exposed to exercise and, therefore, cardiac stress. We therefore studied left ventricular LS at rest and during exercise in T2DM patients vs. healthy controls. METHODS AND RESULTS: Exercise echocardiography was applied with combined breath-by-breath gas exchange analyses in asymptomatic, well-controlled (HbA1c: 6.9 ± 0.7%) T2DM patients (n = 36) and healthy controls (HC, n = 23). Left ventricular LS was assessed at rest and at peak exercise. Peak oxygen uptake (VÌO2peak) and workload (Wpeak) were similar between groups (p > 0.05). Diastolic (E, e's, E/e') and systolic function (left ventricular ejection fraction) were similar at rest and during exercise between groups (p > 0.05). LS (absolute values) was significantly lower at rest and during exercise in T2DM vs. HC (17.0 ± 2.9% vs. 19.8 ± 2% and 20.8 ± 4.0% vs. 23.3 ± 3.3%, respectively, p < 0.05). The response in myocardial deformation (the change in LS from rest up to peak exercise) was similar between groups (+ 3.8 ± 0.6% vs. + 3.6 ± 0.6%, in T2DM vs. HC, respectively, p > 0.05). Multiple regression revealed that HDL-cholesterol, fasted insulin levels and exercise tolerance accounted for 30.5% of the variance in response of myocardial deformation in the T2DM group (p = 0.002). CONCLUSION: Myocardial deformation is reduced in well-controlled T2DM and despite adequate responses, such differences persist during exercise. TRIAL REGISTRATION: NCT03299790, initially released 09/12/2017.
Assuntos
Cardiomiopatias/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Tolerância ao Exercício/fisiologia , Disfunção Ventricular Esquerda/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Bélgica/epidemiologia , Cardiomiopatias/epidemiologia , Cardiomiopatias/patologia , Estudos Transversais , Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Volume Sistólico , Disfunção Ventricular Esquerda/epidemiologia , Adulto JovemRESUMO
Myocardial infarction (MI) occurs when the coronary blood supply is interrupted. As a consequence, cardiomyocytes are irreversibly damaged and lost. Unfortunately, current therapies for MI are unable to prevent progression towards heart failure. As the renewal rate of cardiomyocytes is minimal, the optimal treatment should achieve effective cardiac regeneration, possibly with stem cells transplantation. In that context, our research group identified the cardiac atrial appendage stem cells (CASCs) as a new cellular therapy. However, CASCs are transplanted into a hostile environment, with elevated levels of advanced glycation end products (AGEs), which may affect their regenerative potential. In this study, we hypothesize that pyridoxamine (PM), a vitamin B6 derivative, could further enhance the regenerative capacities of CASCs transplanted after MI by reducing AGEs' formation. Methods and Results: MI was induced in rats by ligation of the left anterior descending artery. Animals were assigned to either no therapy (MI), CASCs transplantation (MI + CASCs), or CASCs transplantation supplemented with PM treatment (MI + CASCs + PM). Four weeks post-surgery, global cardiac function and infarct size were improved upon CASCs transplantation. Interstitial collagen deposition, evaluated on cryosections, was decreased in the MI animals transplanted with CASCs. Contractile properties of resident left ventricular cardiomyocytes were assessed by unloaded cell shortening. CASCs transplantation prevented cardiomyocyte shortening deterioration. Even if PM significantly reduced cardiac levels of AGEs, cardiac outcome was not further improved. Conclusion: Limiting AGEs' formation with PM during an ischemic injury in vivo did not further enhance the improved cardiac phenotype obtained with CASCs transplantation. Whether AGEs play an important deleterious role in the setting of stem cell therapy after MI warrants further examination.
Assuntos
Apêndice Atrial/citologia , Infarto do Miocárdio/terapia , Piridoxamina/uso terapêutico , Transplante de Células-Tronco , Animais , Terapia Combinada , Feminino , Infarto do Miocárdio/tratamento farmacológico , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND/AIMS: High-molecular-weight advanced glycation end-products (HMW-AGEs) are abundantly present in our Western diet. There is growing evidence reporting that HMW-AGEs contribute to the development of cardiovascular dysfunction in vivo, next to the well-known low-molecular-weight AGEs. The goal of our study is to assess the ultrastructure and function of cardiomyocytes after chronic exposure to HMW-AGEs. A better understanding of underlying mechanisms is essential to create new opportunities for further research on the specific role of HMW-AGEs in the development and progression of cardiovascular diseases. METHODS: Adult male rats were randomly assigned to daily intraperitoneal injection for six weeks with either HMW-AGEs (20 mg/kg/day) or a control solution. Hemodynamic measurements were performed at sacrifice. Single cardiomyocytes from the left ventricle were obtained by enzymatic dissociation through retrograde perfusion of the aorta. Unloaded cell shortening, time to peak and time to 50% relaxation were measured during field stimulation and normalized to diastolic length. L-type Ca2+ current density (ICaL) and steady-state inactivation of ICaL were measured during whole-cell ruptured patch clamp. Myofilament functional properties were measured in membrane-permeabilized cardiomyocytes. Ultrastructural examination of cardiac tissue was performed using electron microscopy. RESULTS: Rats injected with HMW-AGEs displayed in vivo cardiac dysfunction, characterized by significant changes in left ventricular peak rate pressure rise and decline accompanied with an increased heart mass. Single cardiomyocytes isolated from the left ventricle revealed concentric hypertrophy, indicated by the increase in cellular width. Unloaded fractional cell shortening was significantly reduced in cells derived from the HMW-AGEs group and was associated with slower kinetics. Peak L-type Ca2+ current density was significantly decreased in the HMW-AGEs group.L-type Ca2+ channel availability was significantly shifted towards more negative potentials after HMW-AGEs injection. The impact of HMW-AGEs on myofilament function was measured in membrane-permeabilized cardiomyocytes showing a reduction in passive force, maximal Ca2+ activated force and rate of force development. Ultrastructural examination of cardiac tissue demonstrated adverse structural remodeling in HMW-AGEs group characterized by a disruption of the cyto-architecture, a decreased mitochondrial density and altered mitochondrial function. CONCLUSION: Our data indicate that HMW-AGEs induce structural and functional cellular remodeling via a different working mechanism as the well-known LMW-AGEs. Results of our research open the door for new strategies targeting HMW-AGEs to improve cardiac outcome.
Assuntos
Acetaldeído/análogos & derivados , Produtos Finais de Glicação Avançada/efeitos adversos , Miócitos Cardíacos/efeitos dos fármacos , Acetaldeído/efeitos adversos , Acetaldeído/metabolismo , Animais , Aorta/fisiopatologia , Doenças Cardiovasculares/fisiopatologia , Diástole/efeitos dos fármacos , Produtos Finais de Glicação Avançada/metabolismo , Cardiopatias/fisiopatologia , Hemodinâmica/efeitos dos fármacos , Masculino , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/ultraestrutura , Ratos , Ratos Sprague-Dawley , Função Ventricular Esquerda/efeitos dos fármacos , Função Ventricular Esquerda/fisiologiaRESUMO
Human cardiac stem cells isolated from atrial appendages based on aldehyde dehydrogenase activity (CASCs) can be expanded in vitro and differentiate into mature cardiomyocytes. In this study, we assess whether Wnt activation stimulates human CASC proliferation, whereas Wnt inhibition induces cardiac maturation. CASCs were cultured as described before. Conventional PCR confirmed the presence of the Frizzled receptors. Small-molecule inhibitors (IWP2, C59, XAV939, and IWR1-endo) and activator (CHIR99021) of the Wnt/ß -catenin signaling pathway were applied, and the effect on ß-catenin and target genes for proliferation and differentiation was assessed by Western blot and RT-qPCR. CASCs express multiple early cardiac differentiation markers and are committed toward myocardial differentiation. They express several Frizzled receptors, suggesting a role for Wnt signaling in clonogenicity, proliferation, and differentiation. Wnt activation increases total and active ß-catenin levels. However, this does not affect CASC proliferation or clonogenicity. Wnt inhibition upregulated early cardiac markers but could not induce mature myocardial differentiation. When CASCs are committed toward myocardial differentiation, the Wnt pathway is active and can be modulated. However, despite its role in cardiogenesis and myocardial differentiation of pluripotent stem-cell populations, our data indicate that Wnt signaling has limited effects on CASC clonogenicity, proliferation, and differentiation.
Assuntos
Apêndice Atrial/citologia , Diferenciação Celular , Regulação da Expressão Gênica , Miócitos Cardíacos/citologia , Células-Tronco/citologia , Via de Sinalização Wnt , Idoso , Idoso de 80 Anos ou mais , Animais , Proliferação de Células , Sobrevivência Celular , Células Cultivadas , Feminino , Coração/fisiologia , Insuficiência Cardíaca/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , SuínosRESUMO
NEW FINDINGS: What is the central question of this study? Does acute exposure to high molecular weight advanced glycation end products (HMW-AGEs) alter cardiomyocyte contractile function? What is the main finding and its importance? Ventricular cardiomyocytes display reduced Ca2+ influx, resulting in reduced contractile capacity, after acute exposure to HMW-AGEs, independent of activation of their receptor. Given that HMW-AGEs are abundantly present in our Western diet, a better understanding of underlying mechanisms, especially in patients already displaying altered cardiac function, should be gained for these compounds. ABSTRACT: Sustained elevated levels of high molecular weight advanced glycation end products (HMW-AGEs) are known to promote cardiac dysfunction. Recent data suggest that acutely elevated levels of AGEs occur in situations of increased oxidative stress. Whether this increase might have detrimental effects on cardiac function remains unknown. In this study, we investigated whether acute exposure to HMW-AGEs affects cardiomyocyte function via activation of their receptor (RAGE) signalling pathway. Single cardiomyocytes from the left ventricle of adult male rats were obtained by enzymatic dissociation through retrograde perfusion of the aorta. Functional experiments were performed in cardiomyocytes pre-incubated with or without an anti-RAGE antibody. Unloaded cell shortening and L-type Ca2+ current amplitude were evaluated in the presence or absence of HMW-AGEs (200 µg ml-1 ). Expression of RAGE, c-Jun N-terminal kinase (JNK) and phosphorylated JNK (pJNK) were assessed by western blot. Experiments were performed at room temperature. After 4 min application of HMW-AGEs, unloaded cell shortening was significantly reduced. This impaired contractile function was related to reduced Ca2+ influx. These alterations were also observed in cardiomyocytes pre-incubated with anti-RAGE antibody. Our study demonstrates that acute exposure to elevated levels of HMW-AGEs leads to direct and irreversible cardiomyocyte dysfunction, independent of RAGE activation.
Assuntos
Produtos Finais de Glicação Avançada/efeitos adversos , Produtos Finais de Glicação Avançada/metabolismo , Contração Miocárdica/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Animais , Dieta Ocidental/efeitos adversos , Produtos Finais de Glicação Avançada/administração & dosagem , Masculino , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Contração Miocárdica/fisiologia , Ratos , Ratos Sprague-Dawley , Receptor para Produtos Finais de Glicação Avançada/metabolismoRESUMO
Advanced glycation end products (AGEs) are a group of proteins and lipids becoming glycated and oxidized after persistent contact with reducing sugars or short-chain aldehydes with amino group and/or high degree of oxidative stress. The accumulation of AGEs in the body is a natural process that occurs with senescence, when the turnover rate of proteins is reduced. However, increased circulating AGEs have been described to arise at early lifetime and are associated with adverse outcome and survival, in particular in settings of cardiovascular diseases. AGEs contribute to the development of cardiac dysfunction by two major mechanisms: cross-linking of proteins or binding to their cell surface receptor. Recently, growing evidence shows that high-molecular weight AGEs (HMW-AGEs) might be as important as the characterized low-molecular weight AGEs (LMW-AGEs). Here, we point out the targets of AGEs in the heart and the mechanisms that lead to heart failure with focus on the difference between LMW-AGEs and the less characterized HMW-AGEs. As such, this review is a compilation of relevant papers in the form of a useful resource tool for researchers who want to further investigate the role of HMW-AGEs on cardiac disorders and need a solid base to start on this specific topic.
Assuntos
Doenças Cardiovasculares/metabolismo , Proteínas Contráteis/metabolismo , Produtos Finais de Glicação Avançada/química , Miocárdio/metabolismo , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Cálcio/metabolismo , Doenças Cardiovasculares/genética , Doenças Cardiovasculares/fisiopatologia , Senescência Celular , Proteínas Contráteis/genética , Regulação da Expressão Gênica , Produtos Finais de Glicação Avançada/classificação , Produtos Finais de Glicação Avançada/metabolismo , Humanos , Peso Molecular , Miocárdio/patologia , Oxirredução , Estresse Oxidativo , Ligação Proteica , Receptor para Produtos Finais de Glicação Avançada/genéticaRESUMO
Scarring and remodeling of the left ventricle (LV) after myocardial infarction (MI) results in ischemic cardiomyopathy with reduced contractile function. Regional differences related to persisting ischemia may exist. We investigated the hypothesis that mitochondrial function and structure is altered in the myocardium adjacent to MI with reduced perfusion (MIadjacent) and less so in the remote, nonischemic myocardium (MIremote). We used a pig model of chronic coronary stenosis and MI (n = 13). Functional and perfusion MR imaging 6 wk after intervention showed reduced ejection fraction and increased global wall stress compared with sham-operated animals (Sham; n = 14). Regional strain in MIadjacent was reduced with reduced contractile reserve; in MIremote strain was also reduced but responsive to dobutamine and perfusion was normal compared with Sham. Capillary density was unchanged. Cardiac myocytes isolated from both regions had reduced basal and maximal oxygen consumption rate, as well as through complex I and II, but complex IV activity was unchanged. Reduced respiration was not associated with detectable reduction of mitochondrial density. There was no significant change in AMPK or glucose transporter expression levels, but glycogen content was significantly increased in both MIadjacent and MIremote Glycogen accumulation was predominantly perinuclear; mitochondria in this area were smaller but only in MIadjacent where also subsarcolemmal mitochondria were smaller. In conclusion, after MI reduction of mitochondrial respiration and glycogen accumulation occur in all LV regions suggesting that reduced perfusion does not lead to additional specific changes and that increased hemodynamic load is the major driver for changes in mitochondrial function.
Assuntos
Cardiomiopatias/metabolismo , Mitocôndrias Cardíacas/metabolismo , Infarto do Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Consumo de Oxigênio , Remodelação Ventricular , Proteínas Quinases Ativadas por AMP/genética , Animais , Western Blotting , Cardiomiopatias/diagnóstico por imagem , Cardiomiopatias/etiologia , Cardiomiopatias/patologia , Respiração Celular , Cicatriz , Estenose Coronária/complicações , Complexo I de Transporte de Elétrons/metabolismo , Complexo II de Transporte de Elétrons/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Proteínas Facilitadoras de Transporte de Glucose/genética , Glicogênio/metabolismo , Imageamento por Ressonância Magnética , Microscopia Eletrônica , Microscopia de Fluorescência , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/etiologia , Infarto do Miocárdio/patologia , Imagem de Perfusão do Miocárdio , Miócitos Cardíacos/ultraestrutura , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Volume Sistólico , Sus scrofa , SuínosRESUMO
RATIONALE: In ventricular myocytes of large mammals with low T-tubule density, a significant number of ryanodine receptors (RyRs) are not coupled to the sarcolemma; cardiac remodeling increases noncoupled RyRs. OBJECTIVE: Our aim was to test the hypothesis that coupled and noncoupled RyRs have distinct microdomain-dependent modulation. METHODS AND RESULTS: We studied single myocytes from pig left ventricle. The T-tubule network was analyzed in 3-dimension (3D) to measure distance to membrane of release sites. The rising phase of the Ca(2+) transient was correlated with proximity to the membrane (confocal imaging, whole-cell voltage-clamp, K5fluo-4 as Ca(2+) indicator). Ca(2+) sparks after stimulation were thus identified as resulting from coupled or noncoupled RyRs. We used high-frequency stimulation as a known activator of Ca(2+)/calmodulin-dependent kinase II. Spark frequency increased significantly more in coupled than in noncoupled RyRs. This specific modulation of coupled RyRs was abolished by the Ca(2+)/calmodulin-dependent kinase II blockers autocamtide-2-related inhibitory peptide and KN-93, but not by KN-92. Colocalization of Ca(2+)/calmodulin-dependent kinase II and RyR was not detectably different for coupled and noncoupled sites, but the F-actin disruptor cytochalasin D prevented the specific modulation of coupled RyRs. NADPH oxidase 2 inhibition by diphenyleneiodonium or apocynin, or global reactive oxygen species scavenging, also prevented coupled RyR modulation. During stimulated Ca(2+) transients, frequency-dependent increase of the rate of Ca(2+) rise was seen in coupled RyR regions only and abolished by autocamtide-2-related inhibitory peptide. After myocardial infarction, selective modulation of coupled RyR was lost. CONCLUSIONS: Coupled RyRs have a distinct modulation by Ca(2+)/calmodulin-dependent kinase II and reactive oxygen species, dependent on an intact cytoskeleton and consistent with a local Ca(2+)/reactive oxygen species microdomain, and subject to modification with disease.
Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/fisiologia , Microdomínios da Membrana/fisiologia , Infarto do Miocárdio/fisiopatologia , Miócitos Cardíacos/fisiologia , Canal de Liberação de Cálcio do Receptor de Rianodina/fisiologia , Sarcolema/fisiologia , Animais , Cálcio/metabolismo , Modelos Animais de Doenças , Imageamento Tridimensional , Microscopia Confocal , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Miócitos Cardíacos/patologia , Técnicas de Patch-Clamp , Espécies Reativas de Oxigênio/metabolismo , Retículo Sarcoplasmático/metabolismo , SuínosRESUMO
Doxorubicin (DOX) is commonly used in cancer treatment but associated with cardiotoxicity. Pyridoxamine (PM), a vitamin B6 derivative, could be a cardioprotectant. This study investigated the effect of PM on DOX cardiotoxicity and DOX antitumor effectiveness. Sprague Dawley rats were treated intravenously with DOX (2 mg/kg/week) or saline over eight weeks. Two other groups received PM via oral intake (1 g/L in water bottles) next to DOX or saline. Echocardiography was performed after eight weeks. PM treatment significantly attenuated the DOX-induced reduction in left ventricular ejection fraction (72 ± 2% vs. 58 ± 3% in DOX; p < 0.001) and increase in left ventricular end-systolic volume (0.24 ± 0.02 µL/cm2 vs. 0.38 ± 0.03 µL/cm2 in DOX; p < 0.0001). Additionally, LA7 tumor cells were exposed to DOX, PM, or DOX and PM for 24 h, 48 h, and 72 h. Cell viability, proliferation, cytotoxicity, and apoptosis were assessed. DOX significantly reduced LA7 cell viability and proliferation (p < 0.0001) and increased cytotoxicity (p < 0.05) and cleaved caspase-3 (p < 0.001). Concomitant PM treatment did not alter the DOX effect on LA7 cells. In conclusion, PM attenuated DOX-induced cardiomyopathy in vivo without affecting the antitumor effect of DOX in vitro, highlighting PM as a promising cardioprotectant for DOX-induced cardiotoxicity.
Assuntos
Cardiomiopatias , Neoplasias Mamárias Animais , Ratos , Animais , Piridoxamina , Cardiotoxicidade/tratamento farmacológico , Volume Sistólico , Ratos Sprague-Dawley , Função Ventricular Esquerda , Doxorrubicina/farmacologiaRESUMO
The use of doxorubicin (DOX) chemotherapy is restricted due to dose-dependent cardiotoxicity. Pyridoxamine (PM) is a vitamin B6 derivative with favorable effects on diverse cardiovascular diseases, suggesting a cardioprotective effect on DOX-induced cardiotoxicity. The cardioprotective nature of PM was investigated in a rat model of DOX-induced cardiotoxicity. Six-week-old female Sprague Dawley rats were treated intravenously with 2 mg/kg DOX or saline (CTRL) weekly for eight weeks. Two other groups received PM via the drinking water next to DOX (DOX+PM) or saline (CTRL+PM). Echocardiography, strain analysis, and hemodynamic measurements were performed to evaluate cardiac function. Fibrotic remodeling, myocardial inflammation, oxidative stress, apoptosis, and ferroptosis were evaluated by various in vitro techniques. PM significantly attenuated DOX-induced left ventricular (LV) dilated cardiomyopathy and limited TGF-ß1-related LV fibrotic remodeling and macrophage-driven myocardial inflammation. PM protected against DOX-induced ferroptosis, as evidenced by restored DOX-induced disturbance of redox balance, improved cytosolic and mitochondrial iron regulation, and reduced mitochondrial damage at the gene level. In conclusion, PM attenuated the development of cardiac damage after DOX treatment by reducing myocardial fibrosis, inflammation, and mitochondrial damage and by restoring redox and iron regulation at the gene level, suggesting that PM may be a novel cardioprotective strategy for DOX-induced cardiomyopathy.
RESUMO
Endurance exercise training is a promising cardioprotective strategy in type 2 diabetes mellitus (T2DM), but the impact of its intensity is not clear. We aimed to investigate whether and how isocaloric moderate-intensity exercise training (MIT) and high-intensity interval exercise training (HIIT) could prevent the adverse cardiac remodeling and dysfunction that develop T2DM in rats. Male rats received a Western diet (WD) to induce T2DM and underwent a sedentary lifestyle (n = 7), MIT (n = 7) or HIIT (n = 8). Insulin resistance was defined as the HOMA-IR value. Cardiac function was assessed with left ventricular (LV) echocardiography and invasive hemodynamics. A qPCR and histology of LV tissue unraveled underlying mechanisms. We found that MIT and HIIT halted T2DM development compared to in sedentary WD rats (p < 0.05). Both interventions prevented increases in LV end-systolic pressure, wall thickness and interstitial collagen content (p < 0.05). In LV tissue, HIIT tended to upregulate the gene expression of an ROS-generating enzyme (NOX4), while both modalities increased proinflammatory macrophage markers and cytokines (CD86, TNF-α, IL-1ß; p < 0.05). HIIT promoted antioxidant and dicarbonyl defense systems (SOD2, glyoxalase 1; p < 0.05) whereas MIT elevated anti-inflammatory macrophage marker expression (CD206, CD163; p < 0.01). We conclude that both MIT and HIIT limit WD-induced T2DM with diastolic dysfunction and pathological LV hypertrophy, possibly using different adaptive mechanisms.
Assuntos
Diabetes Mellitus Tipo 2 , Treinamento Intervalado de Alta Intensidade , Masculino , Ratos , Animais , Diabetes Mellitus Tipo 2/prevenção & controle , Coração , Ventrículos do Coração , Ecocardiografia , HemodinâmicaRESUMO
Microglia activity can drive excessive synaptic loss during the prodromal phase of Alzheimer's disease (AD) and is associated with lowered cyclic adenosine monophosphate (cAMP) due to cAMP phosphodiesterase 4B (PDE4B). This study aimed to investigate whether long-term inhibition of PDE4B by A33 (3 mg/kg/day) can prevent synapse loss and its associated cognitive decline in APPswe/PS1dE9 mice. This model is characterized by a chimeric mouse/human APP with the Swedish mutation and human PSEN1 lacking exon 9 (dE9), both under the control of the mouse prion protein promoter. The effects on cognitive function of prolonged A33 treatment from 20 days to 4 months of age, was assessed at 7-8 months. PDE4B inhibition significantly improved both the working and spatial memory of APPswe/PSdE9 mice after treatment ended. At the cellular level, in vitro inhibition of PDE4B induced microglial filopodia formation, suggesting that regulation of PDE4B activity can counteract microglia activation. Further research is needed to investigate if this could prevent microglia from adopting their 'disease-associated microglia (DAM)' phenotype in vivo. These findings support the possibility that PDE4B is a potential target in combating AD pathology and that early intervention using A33 may be a promising treatment strategy for AD.
Assuntos
Doença de Alzheimer , Cognição , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4 , Modelos Animais de Doenças , Camundongos Transgênicos , Microglia , Inibidores da Fosfodiesterase 4 , Animais , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/metabolismo , Camundongos , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/patologia , Cognição/efeitos dos fármacos , Inibidores da Fosfodiesterase 4/farmacologia , Inibidores da Fosfodiesterase 4/uso terapêutico , Inibidores da Fosfodiesterase 4/administração & dosagem , Microglia/efeitos dos fármacos , Microglia/metabolismo , Microglia/patologia , Presenilina-1/genética , Presenilina-1/metabolismo , Humanos , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , MasculinoRESUMO
Reducing the open probability of the ryanodine receptor (RyR) has been proposed to have beneficial effects in heart failure. We investigated whether conditional FKBP12.6 overexpression at the time of myocardial infarction (MI) could improve cardiac remodelling and cell Ca(2+) handling. Wild-type (WT) mice and mice overexpressing FKBP12.6 (Tg) were studied on average 7.5 ± 0.2 weeks after MI and compared with sham-operated mice for in vivo, myocyte function and remodelling. At baseline, unloaded cell shortening in Tg was not different from WT. The [Ca(2+)](i) transient amplitude was similar, but sarcoplasmic reticulum (SR) Ca(2+) content was larger in Tg, suggesting reduced fractional release. Spontaneous spark frequency was similar despite the increased SR Ca(2+) content, consistent with a reduced RyR channel open probability in Tg. After MI, left ventricular dilatation and myocyte hypertrophy were present in both groups, but more pronounced in Tg. Cell shortening amplitude was unchanged with MI in WT, but increased with MI in Tg. The amplitude of the [Ca(2+)](i) transient was not affected by MI in either genotype, but time to peak was increased; this was most pronounced in Tg. The SR Ca(2+) content and Na(+)- Ca(2+) exchanger function were not affected by MI. Spontaneous spark frequency was increased significantly after MI in Tg, and larger than in WT (at 4 Hz, 2.6 ± 0.4 sparks (100 µm)(-1) s(-1) in Tg MI versus 1.6 ± 0.2 sparks (100 µm)(-1) s(-1) in WT MI; P < 0.05). We conclude that FKPB12.6 overexpression can effectively reduce RyR open probability with maintained cardiomyocyte contraction. However, this approach appears insufficient to prevent and reduce post-MI remodelling, indicating that additional pathways may need to be targeted.
Assuntos
Infarto do Miocárdio/fisiopatologia , Proteínas de Ligação a Tacrolimo/biossíntese , Remodelação Ventricular/efeitos dos fármacos , Animais , Cálcio/metabolismo , Camundongos , Camundongos Transgênicos , Contração Miocárdica/efeitos dos fármacos , Infarto do Miocárdio/metabolismo , Miócitos Cardíacos/fisiologia , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/metabolismo , Trocador de Sódio e Cálcio/metabolismo , Proteínas de Ligação a Tacrolimo/genéticaRESUMO
BACKGROUND: Diabetic cardiomyopathy is characterized by systolic and early diastolic ventricular dysfunction. In the metabolic syndrome (MS), ventricular stiffness is additionally increased in a later stage. It is unknown whether this is related to intrinsic cardiomyocyte dysfunction, extrinsic factors influencing cardiomyocyte contractility and/or cardiac function, or a combination of both. A first aim was to study cardiomyocyte contractility and Ca2+ handling in vitro in a mouse model of MS. A second aim was to investigate whether in vivo hypocaloric diet or ACE-inhibition (ACE-I) improved cardiomyocyte contractility in vitro, contractile reserve and Ca2+ handling. METHODS: This study was performed in LDL-receptor (LDLR-/-) and leptin-deficient (ob/ob), double knock-out mice (DKO), featuring obesity, type II diabetes, atherogenic dyslipidemia and hypertension. Single knock-out LDLR-/-, ob/ob and wild type mice were used as controls. Cellular contractility, Ca2+ handling and their response to in vivo treatment with diet or ACE-I were studied in isolated cardiomyocytes at baseline, during ß-adrenergic stimulation or increased extracellular Ca2+, using field stimulation and patch-clamp. RESULTS: In untreated conditions, prolongation of contraction-relaxation cycle and altered Ca2+ handling are observed in MS. Response to increased extracellular Ca2+ and ß-adrenergic stimulation is impaired and could not be rescued by weight loss. ACE-I restored impaired response to ß-adrenergic stimulation in MS, but not the decreased response to increased extracellular Ca2+. CONCLUSIONS: Cardiomyocyte contractility and ß-adrenergic response are impaired in MS, due to alterations in cellular Ca2+ handling. ACE-I, but not weight loss, is able to restore cardiomyocyte response to ß-adrenergic stimulation in MS.
Assuntos
Agonistas Adrenérgicos beta/farmacologia , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Síndrome Metabólica/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Redução de Peso/fisiologia , Animais , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/fisiologia , Células Cultivadas , Feminino , Masculino , Síndrome Metabólica/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Obesos , Miócitos Cardíacos/patologia , Redução de Peso/efeitos dos fármacosRESUMO
The Na(+)/Ca(2+) exchanger (NCX) is a key regulator of intracellular Ca(2+) in cardiac myocytes, predominantly contributing to Ca(2+) removal during the diastolic relaxation process but also modulating excitation-contraction coupling. NCX is preferentially located in the T-tubules and can be close to or within the dyad, where L-type Ca(2+) channels face ryanodine receptors (RyRs), the Ca(2+) release channels of the sarcoplasmic reticulum. However, especially in larger animals, not all RyRs are in dyads or adjacent to T-tubules, and a substantial fraction of Ca(2+) release from the sarcoplasmic reticulum thus occurs at distance from NCX. This chapter deals with the functional consequences of NCX location and how NCX can modulate diastolic and systolic Ca(2+) events. The loss of T-tubules and the effects on RyR function and NCX modulation are explored, as well as quantitative measurement of local Ca(2+) gradients at the level of the dyadic space.