Beneficial Effects of Physical Exercise on Functional Capacity and Skeletal Muscle Oxidative Stress in Rats with Aortic Stenosis-Induced Heart Failure

Test-retest reliability and minimal detectable change of four functional tests in community-dwelling older adults with high risk of falls

Objectives

This study aimed to quantify test-retest reliability and minimal detectable change (MDC) of the four commonly used functional tests in older adults with a high risk of falling.

Patients and methods

The cross-sectional study was conducted with 30 community-dwelling older adults (26 females, 4 males; mean age: 73.7±6.0 years; range, 65 to 88 years) with a high fall risk identified by the Thai falls risk assessment test between November 2018 and May 2019. Data from the 10-m walk test at a comfortable gait speed (CGS) and fast gait speed (FGS), timed up and go (TUG) test, five times sit to stand test (FTSST), and 6-min walk test (6MWT) were collected twice for each participant. The interval between test sessions was one week. Test-retest reliability was analyzed by the intraclass correlation coefficient (ICC). Standard error of measurement (SEM) and MDC at the 95% confidence interval (MDC95) were also calculated.

Results

The four functional tests had ICC in the range of 0.92 to 0.97. The SEM values of the CGS, FGS, TUG, FTSST, and 6MWT were 0.06 m/sec, 0.04 m/sec, 1.10 sec, 1.30 sec, and 20.60 m, respectively. The MDC95 values of the CGS, FGS, TUG, FTSST, and 6MWT were 0.16 m/sec, 0.12 m/sec, 3.00 sec, 3.50 sec, and 57.20 m, respectively.

Conclusion

All functional tests demonstrated excellent test-retest reliability. The SEM and MDC95 of all functional tests were established. These findings can help clinicians interpret the effectiveness of interventions and determine changes in functional ability over time in older adults at high risk of falls.

Myocardial proteome changes in aortic stenosis rats subjected to long-term aerobic exercise

The effects of exercise training (ET) on the heart of aortic stenosis (AS) rats are controversial and the mechanisms involved in alterations induced by ET have been poorly clarified. In this study, we analyzed the myocardial proteome to identify proteins modulated by moderate-intensity aerobic ET in rats with chronic supravalvular AS. Wistar rats were divided into four groups: sedentary control (C-Sed), exercised control (C-Ex), sedentary aortic stenosis (AS-Sed), and exercised AS (AS-Ex). ET consisted of five treadmill running sessions per week for 16 weeks. Statistical analysis was performed by ANOVA or Kruskal-Wallis and Goodman tests. Results were discussed at a significance level of 5%. At the end of the experiment, AS-Ex rats had higher functional capacity, lower blood lactate concentration, and better cardiac structural and left ventricular (LV) functional parameters than the AS-Sed. Myocardial proteome analysis showed that AS-Sed had higher relative protein abundance related to the glycolytic pathway, oxidative stress, and inflammation, and lower relative protein abundance related to beta-oxidation than C-Sed. AS-Ex had higher abundance of one protein related to mitochondrial biogenesis and lower relative protein abundance associated with oxidative stress and inflammation than AS-Sed. Proteomic data were validated for proteins related to lipid and glycolytic metabolism. Chronic pressure overload changes the abundance of myocardial proteins that are mainly involved in lipid and glycolytic energy metabolism in rats. Moderate-intensity aerobic training attenuates changes in proteins related to oxidative stress and inflammation and increases the COX4I1 protein, related to mitochondrial biogenesis. Protein changes are combined with improved functional capacity, cardiac remodeling, and LV function in AS rats.

Effects of early exercise on cardiac function and lipid metabolism pathway in heart failure

We employed an early training exercise program, immediately after recovery from surgery, and before severe cardiac hypertrophy, to study the underlying mechanism involved with the amelioration of cardiac dysfunction in aortic stenosis (AS) rats. As ET induces angiogenesis and oxygen support, we aimed to verify the effect of exercise on myocardial lipid metabolism disturbance. Wistar rats were divided into Sham, trained Sham (ShamT), AS and trained AS (AST). The exercise consisted of 5-week sessions of treadmill running for 16 weeks. Statistical analysis was conducted by anova or Kruskal-Wallis test and Goodman test. A global correlation between variables was also performed using a two-tailed Pearson's correlation test. AST rats displayed a higher functional capacity and a lower cardiac remodelling and dysfunction when compared to AS, as well as the myocardial capillary rarefaction was prevented. Regarding metabolic properties, immunoblotting and enzymatic assay raised beneficial effects of exercise on fatty acid transport and oxidation pathways. The correlation assessment indicated a positive correlation between variables of angiogenesis and FA utilisation, as well as between metabolism and echocardiographic parameters. In conclusion, early exercise improves exercise tolerance and attenuates cardiac structural and functional remodelling. In parallel, exercise attenuated myocardial capillary and lipid metabolism derangement in rats with aortic stenosis-induced heart failure.

Aerobic Exercise Training Improves Calcium Handling and Cardiac Function in Rats with Heart Failure Resulting from Aortic Stenosis

Aerobic exercise training (AET) has been used to manage heart disease. AET may totally or partially restore the activity and/or expression of proteins that regulate calcium (Ca2+) handling, optimize intracellular Ca2+ flow, and attenuate cardiac functional impairment in failing hearts. However, the literature presents conflicting data regarding the effects of AET on Ca2+ transit and cardiac function in rats with heart failure resulting from aortic stenosis (AoS). This study aimed to evaluate the impact of AET on Ca2+ handling and cardiac function in rats with heart failure due to AoS. Wistar rats were distributed into two groups: control (Sham; n = 61) and aortic stenosis (AoS; n = 44). After 18 weeks, the groups were redistributed into: non-exposed to exercise training (Sham, n = 28 and AoS, n = 22) and trained (Sham-ET, n = 33 and AoS-ET, n = 22) for 10 weeks. Treadmill exercise training was performed with a velocity equivalent to the lactate threshold. The cardiac function was analyzed by echocardiogram, isolated papillary muscles, and isolated cardiomyocytes. During assays of isolated papillary muscles and isolated cardiomyocytes, the Ca2+ concentrations were evaluated. The expression of regulatory proteins for diastolic Ca2+ was assessed via Western Blot. AET attenuated the diastolic dysfunction and improved the systolic function. AoS-ET animals presented an enhanced response to post-rest contraction and SERCA2a and L-type Ca2+ channel blockage compared to the AoS. Furthermore, AET was able to improve aspects of the mechanical function and the responsiveness of the myofilaments to the Ca2+ of the AoS-ET animals. AoS animals presented an alteration in the protein expression of SERCA2a and NCX, and AET restored SERCA2a and NCX levels near normal values. Therefore, AET increased SERCA2a activity and myofilament responsiveness to Ca2+ and improved the cellular Ca2+ influx mechanism, attenuating cardiac dysfunction at cellular, tissue, and chamber levels in animals with AoS and heart failure.

Effects of aerobic exercise on cardiac function and gene expression of NADPH oxidases in diaphragm muscle of rats with aortic stenosis-induced heart failure

We evaluated the influence of aerobic physical exercise (EX) on gene-encoding proteins associated with oxidative stress in diaphragm muscle of rats with aortic stenosis-induced heart failure (HF). Wistar male rats were divided into four groups: Control sedentary (C); Control exercise (C-Ex); Sedentary aortic stenosis (AS); Aortic stenosis exercise (AS-Ex). Exercised rats trained 5 times a week for 10 weeks on a treadmill. Statistical analysis was performed by ANOVA or Kruskal-Wallis test. In the final echocardiogram, animals with aortic stenosis subjected to exercise demonstrated improvement in systolic function compared to the sedentary aortic stenosis group. In diaphragm muscle, the activity of antioxidant enzymes, malondialdehyde malondialdehyde concentration, protein carbonylation, and protein expression of p65 and its inhibitor IκB did not differ between groups. Alterations in gene expression of sources that generate reactive species of oxygen were observed in AS-Ex group, which showed decreased mRNA abundance of NOX2 and NOX4 compared to the aortic stenosis group (p < 0.05). We concluded that aerobic exercise has a positive impact during heart failure, ameliorating systolic dysfunction and biomarkers of oxidative stress in diaphragm muscle of rats with aortic stenosis-induced heart failure.

Influence of Isolated Resistance Exercise on Cardiac Remodeling, Myocardial Oxidative Stress, and Metabolism in Infarcted Rats

INTRODUCTION

Exercise is an important therapeutic strategy for preventing and treating myocardial infarction (MI)-induced cardiac remodeling and heart failure. However, the myocardial effects of resistance exercise on infarcted hearts are not completely established. In this study, we investigated the effects of resistance exercise on structural, functional, and molecular cardiac alterations in infarcted rats.

METHODS

Three months after MI induction or simulated surgery, Wistar rats were assigned into three groups: Sham (n = 14); MI (n = 9); and exercised MI (MI-Ex, n = 13). Exercised rats performed, 3 times a week for 12 weeks, four climbs on a ladder with progressive loads. Cardiac structure and left ventricle (LV) function were analyzed by echocardiogram. Myocyte diameters were evaluated in hematoxylin- and eosin-stained histological sections as the smallest distance between borders drawn across the nucleus. Myocardial energy metabolism, lipid hydroperoxide, malondialdehyde, protein carbonylation, and antioxidant enzyme activities were evaluated by spectrophotometry. Gene expressions of NADPH oxidase subunits were evaluated by RT-PCR. Statistical analyses were performed using ANOVA and Tukey or Kruskal-Wallis and Dunn's test.

RESULTS

Mortality did not differ between the MI-Ex and MI groups. MI had dilated left atrium and LV, with LV systolic dysfunction. Exercise increased the maximum load-carrying capacity, with no changes in cardiac structure or LV function. Myocyte diameters were lower in MI than in Sham and MI-Ex. Lactate dehydrogenase and creatine kinase activity were lower in MI than in Sham. Citrate synthase and catalase activity were lower in MI and MI-Ex than in Sham. Lipid hydroperoxide concentration was lower in MI-Ex than in MI. Nox2 and p22phox gene expressions were higher in MI-Ex than in Sham. Gene expression of Nox4 was higher in MI and MI-Ex than in Sham, and p47phox was lower in MI than in Sham.

CONCLUSION

Late resistance exercise was safe in infarcted rats. Resistance exercise improved maximum load-carrying capacity, reduced myocardial oxidative stress, and preserved myocardial metabolism, with no changes in cardiac structure or left ventricle function in infarcted rats.

Effects of Resistance Exercise on Slow-Twitch Soleus Muscle of Infarcted Rats

Although current guidelines recommend resistance exercise in combination with aerobic training to increase muscle strength and prevent skeletal muscle loss during cardiac remodeling, its effects are not clear. In this study, we evaluated the effects of resistance training on cardiac remodeling and the soleus muscle in long-term myocardial infarction (MI) rats.

METHODS

Three months after MI induction, male Wistar rats were assigned to Sham (n = 14), MI (n = 9), and resistance exercised MI (R-MI, n = 13) groups. The rats trained three times a week for 12 weeks on a climbing ladder. An echocardiogram was performed before and after training. Protein expression of the insulin-like growth factor (IGF)-1/protein kinase B (Akt)/rapamycin target complex (mTOR) pathway was analyzed by Western blot.

RESULTS

Mortality rate was higher in MI than Sham; in the R-MI group, mortality rate was between that in MI and Sham and did not differ significantly from either group. Exercise increased maximal load capacity without changing cardiac structure and left ventricular function in infarcted rats. Infarction size did not differ between infarcted groups. Catalase activity was lower in MI than Sham and glutathione peroxidase lower in MI than Sham and R-MI. Protein expression of p70S6K was lower in MI than Sham and p-FoxO3 was lower in MI than Sham and R-MI. Energy metabolism did not differ between groups, except for higher phosphofrutokinase activity in R-MI than MI.

CONCLUSION

Resistance exercise is safe and increases muscle strength regardless structural and functional cardiac changes in myocardial-infarcted rats. This exercise modality attenuates soleus glycolytic metabolism changes and improves the expression of proteins required for protein turnover and antioxidant response.

Body Surface Potential Mapping during Ventricular Depolarization in Rats after Acute Exhaustive Exercise

BACKGROUND

Exhaustive physical exercise can cause substantial changes in the electrical properties of the myocardium.

OBJECTIVE

To evaluate, using body surface potential mapping, the electrical activity of the heart in rats during ventricular depolarization after acute exhaustive exercise.

METHODS

Twelve-week-old male rats were submitted to acute treadmill exercise at 36 m/min until exhaustion. Unipolar electrocardiograms (ECGs) from the torso surface were recorded in zoletil-anesthetized rats three to five days before (Pre-Ex), 5 and 10 minutes after exhaustive exercise (Post-Ex 5 and Post-Ex 10, respectively) simultaneously with ECGs in limb leads. The instantaneous body surface potential maps (BSPMs) were analyzed during ventricular depolarization. P values <0.05 were considered statistically significant.

RESULTS

Compared with Pre-Ex, an early completion of the second inversion of potential distributions, an early completion of ventricular depolarization, as well as a decrease in the duration of the middle phase and the total duration of ventricular depolarization on BSPMs were revealed at Post-Ex 5. Also, compared with Pre-Ex, an increase in the amplitude of negative BSPM extremum at the R-wave peak on the ECG in lead II (RII-peak) and a decrease in the amplitude of negative BSPM extremum at 3 and 4 ms after RII-peak were showed at Post-Ex 5. At Post-Ex 10, parameters of BSPMs did not differ from those at Pre-Ex.

CONCLUSION

In rats, acute exhaustive exercise causes reversible changes in the temporal and amplitude characteristics of BSPMs during ventricular depolarization, most likely related to alterations in the excitation of the main mass of the ventricular myocardium.

The Role of Oxidative Stress in the Aging Heart

Medical advances and the availability of diagnostic tools have considerably increased life expectancy and, consequently, the elderly segment of the world population. As age is a major risk factor in cardiovascular disease (CVD), it is critical to understand the changes in cardiac structure and function during the aging process. The phenotypes and molecular mechanisms of cardiac aging include several factors. An increase in oxidative stress is a major player in cardiac aging. Reactive oxygen species (ROS) production is an important mechanism for maintaining physiological processes; its generation is regulated by a system of antioxidant enzymes. Oxidative stress occurs from an imbalance between ROS production and antioxidant defenses resulting in the accumulation of free radicals. In the heart, ROS activate signaling pathways involved in myocyte hypertrophy, interstitial fibrosis, contractile dysfunction, and inflammation thereby affecting cell structure and function, and contributing to cardiac damage and remodeling. In this manuscript, we review recent published research on cardiac aging. We summarize the aging heart biology, highlighting key molecular pathways and cellular processes that underlie the redox signaling changes during aging. Main ROS sources, antioxidant defenses, and the role of dysfunctional mitochondria in the aging heart are addressed. As metabolism changes contribute to cardiac aging, we also comment on the most prevalent metabolic alterations. This review will help us to understand the mechanisms involved in the heart aging process and will provide a background for attractive molecular targets to prevent age-driven pathology of the heart. A greater understanding of the processes involved in cardiac aging may facilitate our ability to mitigate the escalating burden of CVD in older individuals and promote healthy cardiac aging.

Effects of Long-Term Regular Continuous and Intermittent Walking on Oxidative Stress, Metabolic Profile, Heart Rate Variability, and Blood Pressure in Older Adults with Hypertension

It is documented that regular exercise is beneficial for improving the antioxidant system, metabolic system, cardiac autonomic function, and blood pressure in those with hypertension. In this regard, low-intensity exercise is recommended for older adults, particularly those with chronic diseases. This study aimed to compare the effects of long-term regular continuous walking with intermittent walking on oxidative stress, metabolic profile, heart rate variability, and blood pressure in older adults with hypertension. Forty-three participants with hypertension aged 60–80 years were randomly divided into the continuous or intermittent walking (CON or INT) groups. Participants in the CON group walked for 30 min, 3 days/week for 12 weeks. Participants in the INT group split 30 min walking into 3 identical sessions punctuated by a 1 min rest after each session, 3 days/week for 12 weeks. Antioxidant and oxidative stress markers, metabolic markers, heart rate variability, and blood pressure were evaluated before and after the exercise program. Glutathione (GSH), GSH to GSH disulfide (GSSG) ratio, and total GSH increased significantly, and GSSG and malondialdehyde decreased significantly in both groups ( $p<0.05$ ) without significant differences between groups. Triglycerides, ratio of total cholesterol to high-density lipoprotein cholesterol, and atherosclerogenic index were significantly lower in the CON group than those in the INT group ( $p<0.05$ ). The standard deviation of the NN intervals and root mean square of the successive differences were significantly higher, and low-frequency power was significantly lower in the INT group than that in the CON group ( $p<0.05$ ). No significant changes in blood pressure were noted in both groups, and nor were there any significant differences between groups. Long-term regular continuous and intermittent walking may comparably increase antioxidants, reduce oxidative stress, and be beneficial for improving important blood pressure-related outcomes, including metabolic profile or cardiac autonomic function in older adults with hypertension.

Cenário Disfuncional dos Principais Componentes Responsáveis pelo Equilíbrio do Trânsito de Cálcio Miocárdico na Insuficiência Cardíaca Induzida por Estenose Aórtica

Fundamento

O remodelamento cardíaco patológico se caracteriza por disfunção diastólica e sistólica, levando à insuficiência cardíaca. Neste contexto, o cenário disfuncional do trânsito de cálcio miocárdico (Ca²⁺) tem sido pouco estudado. Um modelo experimental de estenose aórtica tem sido extensamente utilizado para aprimorar os conhecimentos sobre os principais mecanismos do remodelamento patológico cardíaco.

Objetivo

Entender o processo disfuncional dos principais componentes responsáveis pelo equilíbrio do cálcio miocárdico e sua influência sobre a função cardíaca na insuficiência cardíaca induzida pela estenose aórtica.

Métodos

Ratos Wistar de 21 dias de idade foram distribuídos em dois grupos: controle (placebo; n=28) e estenose aórtica (EaO; n=18). A função cardíaca foi analisada com o ecocardiograma, músculo papilar isolado e cardiomiócitos isolados. No ensaio do músculo papilar, SERCA2a e a atividade do canal de Ca²⁺ do tipo L foram avaliados. O ensaio de cardiomiócitos isolados avaliou o trânsito de cálcio. A expressão proteica da proteínas do trânsito de cálcio foi analisada com o western blot. Os resultados foram estatisticamente significativos quando p <0,05.

Resultados

Os músculos papilares e cardiomiócitos dos corações no grupo EaO demonstraram falhas mecânicas. Os ratos com EaO apresentaram menor tempo de pico do Ca²⁺, menor sensibilidade das miofibrilas do Ca²⁺, prejuízos nos processos de entrada e recaptura de cálcio pelo retículo sarcoplasmático, bem como disfunção no canal de cálcio do tipo L (CCTL). Além disso, os animais com EaO apresentaram maior expressão de SERCA2a, CCTL e trocador de Na⁺/Ca²⁺.

Conclusão

Insuficiência cardíaca sistólica e diastólica devido à estenose aórtica supravalvular acarretou comprometimento da entrada de Ca²⁺ celular e inibição da recaptura de cálcio pelo retículo sarcoplasmático devido à disfunção no CCTL e SERCA2a, assim como mudanças no trânsito de cálcio e na expressão das principais proteínas responsáveis pela homeostase de Ca²⁺ celular.

The poorly conducted orchestra of steroid hormones, oxidative stress and inflammation in frailty needs a maestro: Regular physical exercise

This review outlines the various factors associated with unhealthy aging which includes becoming frail and dependent. With many people not engaging in recommended exercise, facilitators and barriers to engage with exercise must be investigated to promote exercise uptake and adherence over the lifespan for different demographics, including the old, less affluent, women, and those with different cultural-ethnic backgrounds. Governmental and locally funded public health messages and environmental facilitation (gyms, parks etc.) can play an important role. Studies have shown that exercise can act as a conductor to balance oxidative stress, immune and endocrine functions together to promote healthy aging and reduce the risk for age-related morbidities, such as cardiovascular disease and atherosclerosis, and promote cognition and mood over the lifespan. Like a classic symphony orchestra, consisting of four groups of related musical instruments - the woodwinds, brass, percussion, and strings - the aging process should also perform in harmony, with compassion, avoiding the aggrandizement of any of its individual parts during the presentation. This review discusses the wide variety of molecular, cellular and endocrine mechanisms (focusing on the steroid balance) underlying this process and their interrelationships.

Multicomponent Training Prevents Memory Deficit Related to Amyloid-β Protein-Induced Neurotoxicity

BACKGROUND

Alzheimer's disease (AD) is characterized by the accumulation of the amyloid-β peptide in the brain, leading to early oxidative stress and neurotoxicity. It has been suggested that physical exercise could be beneficial in preventing AD, but studies with multicomponent training are scanty.

OBJECTIVE

Verify the effects of multicomponent exercise training to prevent deficits in recognition memory related to Aβ neurotoxicity.

METHODS

We subjected Wistar rats to multicomponent training (including aerobic and anaerobic physical exercise and cognitive exercise) and then infused amyloid-β peptide into their hippocampus.

RESULTS

We show that long-term multicomponent training prevents the amyloid-β-associated neurotoxicity in the hippocampus. It reduces hippocampal lipid peroxidation, restores antioxidant capacity, and increases glutathione levels, finally preventing recognition memory deficits.

CONCLUSION

Multicomponent training avoids memory deficits related to amyloid-β neurotoxicity on an animal model.

Impaired skeletal muscle fatigue resistance during cardiac hypertrophy is prevented by functional overload- or exercise-induced functional capillarity

KEY POINTS

Capillary rarefaction is hypothesized to contribute to impaired exercise tolerance in cardiovascular disease, but it remains a poorly exploited therapeutic target for improving skeletal muscle performance. Using an abdominal aortic coarctation rat model of compensatory cardiac hypertrophy, we determine the efficacy of aerobic exercise for the prevention of, and mechanical overload for, restoration of hindlimb muscle fatigue resistance and microvascular impairment in the early stages of heart disease. Impaired muscle fatigue resistance was found after development of cardiac hypertrophy, but this impairment was prevented by low-intensity aerobic exercise and recovered after mechanical stretch due to muscle overload. Changes in muscle fatigue resistance were closely related to functional (i.e. perfused) microvascular density, independent of arterial blood flow, emphasizing the critical importance of optimal capillary diffusion for skeletal muscle function. Pro-angiogenic therapies are an important tool for improving skeletal muscle function in the incipient stages of heart disease.

ABSTRACT

Microvascular rarefaction may contribute to declining skeletal muscle performance in cardiac and vascular diseases. It remains uncertain to what extent microvascular rarefaction occurs in the earliest stages of these conditions, if impaired blood flow is an aggravating factor and whether angiogenesis restores muscle performance. To investigate this, the effects of aerobic exercise (voluntary wheel running) and functional muscle overload on the performance, femoral blood flow (FBF) and microvascular perfusion of the extensor digitorum longus (EDL) were determined in a chronic rat model of compensatory cardiac hypertrophy (CCH, induced by surgically imposed abdominal aortic coarctation). CCH was associated with hypertension (P = 0.001 vs. Control) and increased relative heart mass (P < 0.001). Immediately upon placing the aortic band (i.e. before development of CCH), post-fatigue test FBF was reduced (P < 0.003), coinciding with attenuated fatigue resistance (P = 0.039) indicating an acute arterial perfusion constraint on muscle performance. While FBF was normalized during CCH in chronic groups (P > 0.05) fatigue resistance remained reduced (P = 0.039) and was associated with reduced (P = 0.009) functional capillarity after development of CCH without intervention, indicating a microvascular limitation to muscle performance. Normalization of functional capillarity after aerobic exercise (P = 0.065) and overload (P = 0.329) in CCH coincided with restoration to control levels of muscle fatigue resistance (P > 0.999), although overload-induced EDL hypertrophy (P = 0.027) and wheel-running velocity and duration (both P < 0.05) were attenuated after aortic banding. These data show that reductions in skeletal muscle performance during CCH can be countered by improving functional capillarity, providing a therapeutic target to improve skeletal muscle function in chronic diseases.

Aerobic Exercise During Advance Stage of Uncontrolled Arterial Hypertension

Aim

To evaluate the influence of physical training on myocardial function, oxidative stress, energy metabolism, and MAPKs and NF-κB signaling pathways in spontaneously hypertensive rats (SHR), at advanced stage of arterial hypertension, which precedes heart failure development.

Methods

We studied four experimental groups: normotensive Wistar rats (W, n = 27), trained W (W-EX, n = 31), SHR (n = 27), and exercised SHR (SHR-EX, n = 32). At 13 months old, the exercise groups underwent treadmill exercise 5 days a week for 4 months. In vitro myocardial function was analyzed in left ventricular (LV) papillary muscle preparations. Antioxidant enzyme activity and energy metabolism were assessed by spectrophotometry. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was analyzed by lucigenin reduction and protein expression by Western blot. Statistical analyzes: ANOVA and Tukey or Kruskal–Wallis and Dunn tests.

Results

SHR-EX had a lower frequency of heart failure features than SHR. Myocardial function and antioxidant enzyme activity were better in SHR-EX than SHR. Lipid hydroperoxide concentration, and phosphorylated JNK and total IkB protein expression were higher in hypertensive than control groups. Malondialdehyde, NADPH oxidase activity, total JNK, phosphorylated p38, phosphorylated and total p65 NF-κB, and phosphorylated IkB did not differ between groups. Protein expression from total p38, and total and phosphorylated ERK were higher in SHR than W. Lactate dehydrogenase and phosphorylated ERK were lower and citrate synthase and β-hydroxyacyldehydrogenase were higher in SHR-EX than SHR.

Conclusion

Exercise improves physical capacity, myocardial function, and antioxidant enzyme activity; reduces the frequency of heart failure features and ERK phosphorylation; and normalizes energy metabolism in SHR.

Effects of Late Aerobic Exercise on Cardiac Remodeling of Rats with Small-Sized Myocardial Infarction

Fundamento:

O exercício físico tem sido considerado uma importante terapia não farmacológica para a prevenção e tratamento das doenças cardiovasculares. No entanto, seus efeitos na remodelação cardíaca leve não são claros.

Objetivo:

Avaliar a influência do exercício aeróbico sobre a capacidade funcional, estrutura cardíaca, função ventricular esquerda (VE) e expressão gênica das subunidades da NADPH oxidase em ratos com infarto do miocárdio pequeno (IM).

Métodos:

Três meses após a indução do IM, ratos Wistar foram divididos em três grupos: Sham; IM sedentário (IM-SED); e IM exercício aeróbico (IM-EA). Os ratos se exercitaram em uma esteira três vezes por semana durante 12 semanas. Um ecocardiograma foi realizado antes e após o treinamento. O tamanho do infarto foi avaliado por histologia e a expressão gênica por RT-PCR. O nível de significância para análise estatística foi estabelecido em 5%.

Resultados:

Ratos com IM menor que 30% da área total do VE foram incluídos no estudo. A capacidade funcional foi maior no IM-EA do que nos ratos Sham e IM-SED. O tamanho do infarto não diferiu entre os grupos. Ratos infartados apresentaram aumento do diâmetro diastólico e sistólico do VE, diâmetro do átrio esquerdo e massa do VE, com disfunção sistólica. A espessura relativa da parede foi menor no grupo IM-SED do que nos grupos IM-EA e Sham. A expressão gênica das subunidades NADPH oxidase NOX2, NOX4, p22^phox e p47^phox não diferiu entre os grupos.

Conclusão:

Infarto do miocárdio pequeno altera a estrutura cardíaca e a função sistólica do VE. O exercício aeróbico tardio pode melhorar a capacidade funcional e a remodelação cardíaca por meio da preservação da geometria ventricular esquerda. A expressão gênica das subunidades da NADPH oxidase não está envolvida na remodelação cardíaca, nem é modulada pelo exercício aeróbico em ratos com infarto do miocárdio pequeno.

Effects of aerobic and resistance exercise on cardiac remodelling and skeletal muscle oxidative stress of infarcted rats

We compared the influence of aerobic and resistance exercise on cardiac remodelling, physical capacity and skeletal muscle oxidative stress in rats with MI‐induced heart failure. Three months after MI induction, Wistar rats were divided into four groups: Sham; sedentary MI (S‐MI); aerobic exercised MI (A‐MI); and resistance exercised MI (R‐MI). Exercised rats trained three times a week for 12 weeks on a treadmill or ladder. Statistical analysis was performed by ANOVA or Kruskal‐Wallis test. Functional aerobic capacity was greater in A‐MI and strength gain higher in R‐MI. Echocardiographic parameters did not differ between infarct groups. Reactive oxygen species production, evaluated by fluorescence, was higher in S‐MI than Sham, and lipid hydroperoxide concentration was lower in A‐MI than the other groups. Glutathione peroxidase activity was higher in A‐MI than S‐MI and R‐MI. Superoxide dismutase was lower in S‐MI than Sham and R‐MI. Gastrocnemius cross‐sectional area, satellite cell activation and expression of the ubiquitin‐proteasome system proteins did not differ between groups. In conclusion, aerobic exercise and resistance exercise improve functional capacity and maximum load carrying, respectively, without changing cardiac remodelling in infarcted rats. In the gastrocnemius, infarction increases oxidative stress and changes antioxidant enzyme activities. Aerobic exercise reduces oxidative stress and attenuates superoxide dismutase and glutathione peroxidase changes.

Exercise-Induced Regulation of Redox Status in Cardiovascular Diseases: The Role of Exercise Training and Detraining

Although low levels of reactive oxygen species (ROS) are beneficial for the organism ensuring normal cell and vascular function, the overproduction of ROS and increased oxidative stress levels play a significant role in the onset and progression of cardiovascular diseases (CVDs). This paper aims at providing a thorough review of the available literature investigating the effects of acute and chronic exercise training and detraining on redox regulation, in the context of CVDs. An acute bout of either cardiovascular or resistance exercise training induces a transient oxidative stress and inflammatory response accompanied by reduced antioxidant capacity and enhanced oxidative damage. There is evidence showing that these responses to exercise are proportional to exercise intensity and inversely related to an individual’s physical conditioning status. However, when chronically performed, both types of exercise amplify the antioxidant defense mechanism, reduce oxidative stress and preserve redox status. On the other hand, detraining results in maladaptations within a time-frame that depends on the exercise training intensity and mode, as high-intensity training is superior to low-intensity and resistance training is superior to cardiovascular training in preserving exercise-induced adaptations during detraining periods. Collectively, these findings suggest that exercise training, either cardiovascular or resistance or even a combination of them, is a promising, safe and efficient tool in the prevention and treatment of CVDs.

Low-intensity aerobic exercise improves cardiac remodelling of adult spontaneously hypertensive rats

We evaluated the influence of aerobic training on cardiac remodeling in untreated spontaneously hypertensive rats (SHR). Four experimental groups were used: sedentary (W‐SED, n=27) and trained (WEX, n=31) normotensive Wistar rats, and sedentary (SHR‐SED, n=27) and exercised (SHR‐EX, n=32) hypertensive rats. At 13 months old, trained groups underwent treadmill exercise five days a week for four months. Statistical analysis: ANOVA or Kruskal‐Wallis. Exercised groups had higher physical capacity. Hypertensive groups presented left ventricular (LV) concentric hypertrophy with impaired function. Left atrium diameter, LV posterior wall thickness and relative thickness, and isovolumetric relaxation time were lower in SHR‐EX than SHR‐SED. Interstitial collagen fraction and Type I‐Type III collagen ratio were higher in SHR‐SED than W‐SED. In SHR‐EX these parameters had intermediate values between W‐EX and SHRSED with no differences between either group. Myocardial matrix metalloproteinase‐2 activity, evaluated by zymography, was higher in SHR‐SED than W‐SED and SHR‐EX. TIMP‐2 was higher in hypertensive than normotensive groups. In conclusion, low intensity aerobic exercise reduces left atrium dimension and LV posterior wall thickness, and improves functional capacity, diastolic function, and metalloproteinase‐2 activity in adult SHR.

Influence of intermittent fasting on myocardial infarction-induced cardiac remodeling

Background

Information on the role of intermittent fasting (IF) on pathologic cardiac remodeling is scarce. We compared the effects of IF before and after myocardial infarction (MI) on rat cardiac remodeling and survival.

Methods

Wistar rats were intermittently fasted (food available every other day) or fed ad libitum for 12 weeks and then divided into three groups: AL – fed ad libitum; AL/IF - fed AL before MI and IF after MI; and IF – fed IF before and after MI. Echocardiogram was performed before MI and 2 and 12 weeks after surgery. Isolated hearts were evaluated in Langendorff preparations.

Results

Before surgery, body weight (BW) was lower in IF than AL. Final BW was lower in AL/IF and IF than AL. Perioperative mortality did not change between AL (31.3%) and IF (27.3%). Total mortality was lower in IF than AL. Before surgery, echocardiographic parameters did not differ between groups. Two weeks after surgery, MI size did not differ between groups. Twelve weeks after MI, left ventricular (LV) diastolic posterior wall thickness was lower in AL/IF and IF than AL. The percentage of variation of echocardiographic parameters between twelve and two weeks showed that MI size decreased in all groups and the reduction was higher in IF than AL/IF. In Langendorff preparations, LV volume at zero end-diastolic pressure (V0; AL: 0.41 ± 0.05; AL/IF: 0.34 ± 0.06; IF: 0.28 ± 0.05 mL) and at 25 mmHg end-diastolic pressure (V25; AL: 0.61 ± 0.05; AL/IF: 0.54 ± 0.07; IF: 0.44 ± 0.06 mL) was lower in AL/IF and IF than AL and V25 was lower in IF than AL/IF. V0/BW ratio was lower in IF than AL and LV weight/V0 ratio was higher in IF than AL. Myocyte diameter was lower in AL/IF and IF than AL (AL: 17.3 ± 1.70; AL/IF: 15.1 ± 2.21; IF: 13.4 ± 1.49 μm). Myocardial hydroxyproline concentration and gene expression of ANP, Serca 2a, and α- and β-myosin heavy chain did not differ between groups.

Conclusion

Intermittent fasting initiated before or after MI reduces myocyte hypertrophy and LV dilation. Myocardial fibrosis and fetal gene expression are not modulated by feeding regimens. Benefit is more evident when intermittent fasting is initiated before rather than after MI.

Curcumin improves exercise performance of mice with coronary artery ligation-induced HFrEF: Nrf2 and antioxidant mechanisms in skeletal muscle

A hallmark of chronic heart failure (HF) with low ejection fraction (HFrEF) is exercise intolerance. We hypothesized that reduced expression of nuclear factor E2-related factor 2 (Nrf2) in skeletal muscle contributes to impaired exercise performance. We further hypothesized that curcumin, a Nrf2 activator, would preserve or increase exercise capacity in HF. Experiments were carried out in mice with coronary artery ligation-induced HFrEF. Curcumin was deliveried by a subcutaneous osmotic minipump at a dose of 50 mg·kg^-1·day^-1 for 8 weeks. In vivo, in situ, and in vitro experiments were employed to evaluate exercise capacity, muscle function, and molecular mechanisms. We found that: 1) the maximal speed, running distance to exhaustion, and limb grip force were significantly lower in HFrEF mice compared with sham. Curcumin-treated HF mice displayed enhanced exercise performance compared with vehicle-treated HF mice; 2) both soleus (Sol) and extensor digitorum longus (EDL) muscles of HFrEF mice exhibited reduced force and rapid fatigue, which were ameliorated by curcumin; and 3) protein expression of Nrf2, hemeoxygenase-1, SOD2, myogenin, and MyoD were significantly lower, but total ubiquitinated proteins, MURF1, and atrogen-1 were higher in Sol and EDL of HFrEF compared with sham mice, whereas these alterations in Nrf2 signaling and antioxidant defenses in HFrEF were attenuated by curcumin, which had no effect on cardiac function per se in mice with severe HFrEF. These data suggest that impaired Nrf2 signaling intrinsic to skeletal muscle contributes to exercise intolerance in HFrEF. Skeletal muscle Nrf2 should be considered as a novel therapeutic target in severe HF. NEW & NOTEWORTHY These studies suggest that impaired nuclear factor E2-related factor 2 (Nrf2) signaling is a critical mechanism underlying the enhanced oxidative stress in skeletal muscle in heart failure with low ejection fraction (HFrEF). Curcumin prevents the decline in running performance in HFrEF mice by upregulating antioxidant defenses in skeletal muscle, likely mediated by activating Nrf2 signaling. These findings suggest a novel therapeutic target for the improvement of exercise capacity and quality of life in HFrEF patients.

Exercise during transition from compensated left ventricular hypertrophy to heart failure in aortic stenosis rats

We evaluated the influence of aerobic exercise on cardiac remodelling during the transition from compensated left ventricular (LV) hypertrophy to clinical heart failure in aortic stenosis (AS) rats. Eighteen weeks after AS induction, rats were assigned into sedentary (AS) and exercised (AS-Ex) groups. Results were compared to Sham rats. Exercise was performed on treadmill for 8 weeks. Exercise improved functional capacity. Echocardiogram showed no differences between AS-Ex and AS groups. After exercise, fractional shortening and ejection fraction were lower in AS-Ex than Sham. Myocyte diameter and interstitial collagen fraction were higher in AS and AS-Ex than Sham; however, myocyte diameter was higher in AS-Ex than AS. Myocardial oxidative stress, evaluated by lipid hydroperoxide concentration, was higher in AS than Sham and was normalized by exercise. Gene expression of the NADPH oxidase subunits NOX2 and NOX4, which participate in ROS generation, did not differ between groups. Activity of the antioxidant enzyme superoxide dismutase was lower in AS and AS-Ex than Sham and glutathione peroxidase was lower in AS-Ex than Sham. Total and reduced myocardial glutathione, which is involved in cellular defence against oxidative stress, was lower in AS than Sham and total glutathione was higher in AS-Ex than AS. The MAPK JNK was higher in AS-Ex than Sham and AS groups. Phosphorylated P38 was lower in AS-Ex than AS. Despite improving functional capacity, aerobic exercise does not change LV function in AS rats. Exercise restores myocardial glutathione, reduces oxidative stress, impairs JNK signalling and further induces myocyte hypertrophy.

Influence of apocynin on cardiac remodeling in rats with streptozotocin-induced diabetes mellitus

Background

Increased reactive oxygen species (ROS) generation in diabetes mellitus (DM) is an important mechanism leading to diabetic cardiomyopathy. Apocynin, a drug isolated from the herb Picrorhiza kurroa, is considered an antioxidant agent by inhibiting NADPH oxidase activity and improving ROS scavenging. This study analyzed the influence of apocynin on cardiac remodeling in diabetic rats.

Methods

Six-month-old male Wistar rats were assigned into 4 groups: control (CTL, n = 15), control + apocynin (CTL + APO, n = 20), diabetes (DM, n = 20), and diabetes + apocynin (DM + APO, n = 20). DM was induced by streptozotocin. Seven days later, apocynin (16 mg/kg/day) or vehicle was initiated and maintained for 8 weeks. Left ventricular (LV) histological sections were used to analyze interstitial collagen fraction. NADPH oxidase activity was evaluated in LV samples. Comparisons between groups were performed by ANOVA for a 2 × 2 factorial design followed by the Bonferroni post hoc test.

Results

Body weight (BW) was lower and glycemia higher in diabetic animals. Echocardiogram showed increased left atrial diameter, LV diastolic diameter, and LV mass indexed by BW in both diabetic groups; apocynin did not affect these indices. LV systolic function was impaired in DM groups and unchanged by apocynin. Isovolumic relaxation time was increased in DM groups; transmitral E/A ratio was higher in DM + APO compared to DM. Myocardial functional evaluation through papillary muscle preparations showed impaired contractile and relaxation function in both DM groups at baseline conditions. After positive inotropic stimulation, developed tension (DT) was lower in DM than CTL. In DM + APO, DT had values between those in DM and CTL + APO and did not significantly differ from either group. Myocardial interstitial collagen fraction was higher in DM than CTL and did not differ between DM + APO and CTL + APO. Serum activity of antioxidant enzymes glutathione peroxidase, superoxide dismutase (SOD), and catalase was lower in DM than CTL; apocynin restored catalase and SOD levels in DM + APO. Myocardial NADPH oxidase activity did not differ between groups.

Conclusion

Apocynin restores serum antioxidant enzyme activity despite unchanged myocardial NADPH oxidase activity in diabetic rats.

Reactive Oxygen Species as Intracellular Signaling Molecules in the Cardiovascular System

BACKGROUND

Redox signaling plays an important role in the lives of cells. This signaling not only becomes apparent in pathologies but is also thought to be involved in maintaining physiological homeostasis. Reactive Oxygen Species (ROS) can activate protein kinases: CaMKII, PKG, PKA, ERK, PI3K, Akt, PKC, PDK, JNK, p38. It is unclear whether it is a direct interaction of ROS with these kinases or whether their activation is a consequence of inhibition of phosphatases. ROS have a biphasic effect on the transport of Ca2+ in the cell: on one hand, they activate the sarcoplasmic reticulum Ca2+-ATPase, which can reduce the level of Ca2+ in the cell, and on the other hand, they can inactivate Ca2+-ATPase of the plasma membrane and open the cation channels TRPM2, which promote Ca2+-loading and subsequent apoptosis. ROS inhibit the enzyme PHD2, which leads to the stabilization of HIF-α and the formation of the active transcription factor HIF.

CONCLUSION

Activation of STAT3 and STAT5, induced by cytokines or growth factors, may include activation of NADPH oxidase and enhancement of ROS production. Normal physiological production of ROS under the action of cytokines activates the JAK/STAT while excessive ROS production leads to their inhibition. ROS cause the activation of the transcription factor NF-κB. Physiological levels of ROS control cell proliferation and angiogenesis. ROS signaling is also involved in beneficial adaptations to survive ischemia and hypoxia, while further increases in ROS can trigger programmed cell death by the mechanism of apoptosis or autophagy. ROS formation in the myocardium can be reduced by moderate exercise.

High, but not low, exercise volume shifts the balance of renin-angiotensin system toward ACE2/Mas receptor axis in skeletal muscle in obese rats

Metabolic syndrome is a cluster of metabolic risk factors that is linked to central obesity, elevated blood pressure, insulin resistance (IR), and dyslipidemia, where the renin-angiotensin system (RAS) may provide a link among them. This study aimed to evaluate volume exercise effects comparing low vs. high volume of chronic aerobic exercise on RAS axes in skeletal muscle in a diet-induced obesity (DIO) rat model. For this, male Wistar-Kyoto rats were fed a standard chow (SC) diet or a high-fat (HF) diet for 32 wk. Animals receiving the HF diet were randomly divided into low exercise volume (LEV, 150 min/wk) and high exercise volume (HEV, 300 min/wk) at the 20th week. After 12 wk of aerobic treadmill training, the body mass and composition, blood pressure, glucose and lipid metabolism, RAS axes, insulin signaling, and inflammatory pathway were performed. HEV slowed the body mass gain, reduced intra-abdominal fat pad and leptin levels, improved total and peripheral body composition and inflammatory cytokine, reduced angiotensin II type 1 receptor expression, and increased Mas receptor protein expression compared with the HF animals. Sedentary groups (SC and HF) presented lower time to exhaustion and maximal velocity compared with the LEV and HEV groups. Both exercise training groups showed reduced resting systolic blood pressure and heart rate, improved glucose tolerance, IR, insulin signaling, and lipid profile. We conclude that the HEV, but not LEV, shifted the balance of RAS toward the ACE2/Mas receptor axis in skeletal muscle, presenting protective effects against the DIO model.

Skeletal muscle aging: influence of oxidative stress and physical exercise

Skeletal muscle abnormalities are responsible for significant disability in the elderly. Sarcopenia is the main alteration occurring during senescence and a key public health issue as it predicts frailty, poor quality of life, and mortality. Several factors such as reduced physical activity, hormonal changes, insulin resistance, genetic susceptibility, appetite loss, and nutritional deficiencies are involved in the physiopathology of muscle changes. Sarcopenia is characterized by structural, biochemical, molecular and functional muscle changes. An imbalance between anabolic and catabolic intracellular signaling pathways and an increase in oxidative stress both play important roles in muscle abnormalities. Currently, despite the discovery of new targets and development of new drugs, nonpharmacological therapies such as physical exercise and nutritional support are considered the basis for prevention and treatment of age-associated muscle abnormalities. There has been an increase in information on signaling pathways beneficially modulated by exercise; nonetheless, studies are needed to establish the best type, intensity, and frequency of exercise to prevent or treat age-induced skeletal muscle alterations.

Effects of growth hormone on cardiac remodeling and soleus muscle in rats with aortic stenosis-induced heart failure

Background

Skeletal muscle wasting is often observed in heart failure (HF). The growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis is impaired in HF. In this study, we evaluated the effects of GH on soleus muscle and cardiac remodeling in rats with aortic stenosis (AS)-induced HF.

Methods

AS was created by placing a stainless-steel clip on the ascending aorta. After clinically detecting HF, GH (2 mg/kg/day) was subcutaneously injected for 14 days (AS-GH group). Results were compared with those from Sham and non-treated AS groups. Transthoracic echocardiogram was performed before and after treatment. Protein expression was evaluated by Western blot and satellite cells activation by immunofluorescence. Statistical analyzes: ANOVA and Tukey or Kruskal-Wallis and Student-Newman-Keuls.

Results

Before treatment both AS groups presented a similar degree of cardiac injury. GH prevented body weight loss and attenuated systolic dysfunction. Soleus cross-sectional fiber areas were lower in both AS groups than Sham (Sham 3,556±447; AS 2,882±422; AS-GH 2,868±591 μm²; p=0.016). GH increased IGF-1 serum concentration (Sham 938±83; AS 866±116; AS-GH 1167±166 ng/mL; p<0.0001) and IGF-1 muscle protein expression and activated PI3K protein. Neural cell adhesion molecule (NCAM) immunofluorescence was increased in both AS groups. Catabolism-related intracellular pathways did not differ between groups.

Conclusion

Short-term growth hormone attenuates left ventricular systolic dysfunction in rats with aortic stenosis-induced HF. Despite preserving body weight, increasing serum and muscular IGF-1 levels, and stimulating PI3K muscle expression, GH does not modulate soleus muscle trophism, satellite cells activation or intracellular pathways associated with muscle catabolism.

Neurovascular control during exercise in acute coronary syndrome patients with Gln27Glu polymorphism of β2-adrenergic receptor

Background

Gln27Glu (rs1042714) polymorphism of the β₂-adrenergic receptor (ADRB2) has been association with cardiovascular functionality in healthy subjects. However, it is unknown whether the presence of the ADRB2 Gln27Glu polymorphism influences neurovascular responses during exercise in patients with acute coronary syndromes (ACS). We tested the hypothesis that patients with ACS homozygous for the Gln allele would have increased muscle sympathetic nerve activity (MSNA) responses and decreased forearm vascular conductance (FVC) responses during exercise compared with patients carrying the Glu allele (Gln27Glu and Glu27Glu). In addition, exercise training would restore these responses in Gln27Gln patients.

Methods and results

Thirty-days after an ischemic event, 61 patients with ACS without ventricular dysfunction were divided into 2 groups: (1) Gln27Gln (n = 35, 53±1years) and (2) Gln27Glu+Glu27Glu (n = 26, 52±2years). MSNA was directly measured using the microneurography technique, blood pressure (BP) was measured with an automatic oscillometric device, and blood flow was measured using venous occlusion plethysmography. MSNA, mean BP, and FVC were evaluated at rest and during a 3-min handgrip exercise. The MSNA (P = 0.02) and mean BP (P = 0.04) responses during exercise were higher in the Gln27Gln patients compared with that in the Gln27Glu+Glu27Glu patients. No differences were found in FVC. Two months of exercise training significantly decreased the MSNA levels at baseline (P = 0.001) and in their response during exercise (P = 0.02) in Gln27Gln patients, but caused no changes in Gln27Glu+Glu27Glu patients. Exercise training increased FVC responses in Gln27Glu+Glu27Glu patients (P = 0.03), but not in Gln27Gln patients.

Conclusion

The exaggerated MSNA and mean BP responses during exercise suggest an increased cardiovascular risk in patients with ACS and Gln27Gln polymorphism. Exercise training emerges as an important strategy for restoring this reflex control. Gln27Glu polymorphism of ADRB2 influences exercise-induced vascular adaptation in patients with ACS.

Physical Exercise Is a Potential "Medicine" for Atherosclerosis

Cardiovascular disease (CVD) has been recognized as the number one killer for decades. The most well-known risk factor is atherosclerosis. Unlike the acuity of CVD, atherosclerosis is a chronic, progressive pathological change. This process involves inflammatory response, oxidative reaction, macrophage activity, and different interaction of inflammatory factors. Physical exercise has long been known as good for health in general. In recent studies, physical exercise has been demonstrated to be a therapeutic tool for atherosclerosis. However, its therapeutic effect has dosage-dependent effect. Un-proper over exercise might also cause damage to the heart. Here we summarize the mechanism of Physical exercise's beneficial effects and its potential clinical use.

Cardiac Cachexia: Perspectives for Prevention and Treatment

Cachexia is a prevalent pathological condition associated with chronic heart failure. Its occurrence predicts increased morbidity and mortality independent of important clinical variables such as age, ventricular function, or heart failure functional class. The clinical consequences of cachexia are dependent on both weight loss and systemic inflammation, which accompany cachexia development. Skeletal muscle wasting is an important component of cachexia; it often precedes cachexia development and predicts poor outcome in heart failure. Cachexia clinically affects several organs and systems. It is a multifactorial condition where underlying pathophysiological mechanisms are not completely understood making it difficult to develop specific prevention and treatment therapies. Preventive strategies have largely focused on muscle mass preservation. Different treatment options have been described, mostly in small clinical studies or experimental settings. These include nutritional support, neurohormonal blockade, reducing intestinal bacterial translocation, anemia and iron deficiency treatment, appetite stimulants, immunomodulatory agents, anabolic hormones, and physical exercise regimens. Currently, nonpharmacological therapy such as nutritional support and physical exercise are considered central to cachexia prevention and treatment.

Apocynin influence on oxidative stress and cardiac remodeling of spontaneously hypertensive rats with diabetes mellitus

PURPOSE

Although increased oxidative stress is a major component of diabetic hypertensive cardiomyopathy, research into the effects of antioxidants on cardiac remodeling remains scarce. The actions of antioxidant apocynin include inhibiting reactive oxygen species (ROS) generation by nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and ROS scavenging. We evaluated the effects of apocynin on cardiac remodeling in spontaneously hypertensive rats (SHR) with diabetes mellitus (DM).

METHODS

Male SHR were divided into four groups: control (SHR, n = 16); SHR treated with apocynin (SHR-APO; 16 mg/kg/day, added to drinking water; n = 16); diabetic SHR (SHR-DM, n = 13); and SHR-DM treated with apocynin (SHR-DM-APO, n = 14), for eight weeks. DM was induced by streptozotocin (40 mg/kg, single dose). Statistical analyzes: ANOVA and Tukey or Mann-Whitney.

RESULTS

Echocardiogram in diabetic groups showed higher left ventricular and left atrium diameters indexed for body weight, and higher isovolumetric relaxation time than normoglycemic rats; systolic function did not differ between groups. Isolated papillary muscle showed impaired contractile and relaxation function in diabetic groups. Developed tension was lower in SHR-APO than SHR. Myocardial hydroxyproline concentration was higher in SHR-DM than SHR, interstitial collagen fraction was higher in SHR-DM-APO than SHR-APO, and type III collagen protein expression was lower in SHR-DM and SHR-DM-APO than their controls. Type I collagen and lysyl oxidase expression did not differ between groups. Apocynin did not change collagen tissue. Myocardial lipid hydroperoxide concentration was higher in SHR-DM than SHR and SHR-DM-APO. Glutathione peroxidase activity was lower and catalase higher in SHR-DM than SHR. Apocynin attenuated antioxidant enzyme activity changes in SHR-DM-APO. Advanced glycation end-products and NADPH oxidase activity did not differ between groups.

CONCLUSION

Apocynin reduces oxidative stress independently of NADPH oxidase activity and does not change ventricular or myocardial function in spontaneously hypertensive rats with diabetes mellitus. The apocynin-induced myocardial functional impairment in SHR shows that apocynin actions need to be clarified during sustained chronic pressure overload.

Effects of early aldosterone antagonism on cardiac remodeling in rats with aortic stenosis-induced pressure overload

Aldosterone plays a pivotal role in the pathophysiology of systolic heart failure. However, whether early aldosterone antagonism improves cardiac remodeling during persistent pressure overload is unsettled. We evaluated the effects of aldosterone antagonist spironolactone on cardiac remodeling in rats with ascending aortic stenosis (AS).

METHODS

Three days after inducing AS, weaning rats were randomized to receive spironolactone (AS-SPR, 20mg/kg/day) or no drug (AS) for 18weeks, and compared with sham-operated rats. Myocardial function was studied in isolated left ventricular (LV) papillary muscles.

STATISTICAL ANALYSES

ANOVA or Kruskal-Wallis tests.

RESULTS

Echocardiogram showed that LV diastolic (Sham 8.73±0.57; AS 8.30±1.10; AS-SPR 9.19±1.15mm) and systolic (Sham 4.57±0.67; AS 3.61±1.49; AS-SPR 4.62±1.48mm) diameters, left atrial diameter (Sham 5.80±0.44; AS 7.15±1.22; AS-SPR 8.02±1.17mm), and LV mass were higher in AS-SPR than AS. Posterior wall shortening velocity (Sham 38.5±3.8; AS 35.6±5.6; AS-SPR 31.1±3.8mm/s) was lower in AS-SPR than Sham and AS; E/A ratio was higher in AS-SPR than Sham. Developed tension was lower in AS and AS-SPR than Sham. Time to peak tension was higher in AS-SPR than Sham and AS after post-rest contraction. Right ventricle weight was higher in AS-SPR than AS, suggesting more severe heart failure in AS-SPR than AS. Interstitial collagen fractional area and myocardial hydroxyproline concentration were higher in AS than Sham. Metalloproteinase-2 and -9 activity, evaluated by zymography, did not differ between groups.

CONCLUSION

Early spironolactone administration causes further hypertrophy in cardiac chambers, and left ventricular dilation and dysfunction in rats with AS-induced chronic pressure overload.

Diagnostic, Prognostic, and Therapeutic Value of Circulating miRNAs in Heart Failure Patients Associated with Oxidative Stress

Heart failure is a major public health problem especially in the aging population (≥65 years old), affecting nearly 5 million Americans and 15 million European people. Effective management of heart failure (HF) depends on a correct and rapid diagnosis. Presently, BNP (brain natriuretic peptide) or N-terminal pro-brain natriuretic peptide (NT-proBNP) assay is generally accepted by the international community for diagnostic evaluation and risk stratification of patients with HF. However, regardless of its widespread clinical use, BNP is still encumbered by reduced specificity. As a result, diagnosis of heart failure remains challenging. Although significant improvement happened in the clinical management of HF over the last 2 decades, traditional treatments are ultimately ineffective in many patients who progress to advanced HF. Therefore, a novel diagnostic, prognostic biomarker and new therapeutic approach are required for clinical management of HF patients. Circulating miRNAs seem to be the right choice for novel noninvasive biomarkers as well as new treatment strategies for HF. In this review, we briefly discuss the diagnostic, prognostic, and therapeutic role of circulating miRNAs in heart failure patients. We also mentioned our own technique of extraction of RNA and detection of circulating miRNAs from human plasma and oxidative stress associated miRNAs with HF.