Exercise training in hypertension: Role of microRNAs

Modulating the Expression of Exercise-induced lncRNAs: Implications for Cardiovascular Disease Progression

Recent research shows exercise is good for heart health, emphasizing the importance of physical activity. Sedentary behavior increases the risk of cardiovascular disease, while exercise can help prevent and treat it. Additionally, physical exercise can modulate the expression of lncRNAs, influencing cardiovascular disease progression. Therefore, understanding this relationship could help identify prospective biomarkers and therapeutic targets pertaining to cardiovascular ailments. This review has underscored recent advancements concerning the potential biomarkers of lncRNAs in cardiovascular diseases, while also summarizing existing knowledge regarding dysregulated lncRNAs and their plausible molecular mechanisms. Additionally, we have contributed novel perspectives on the underlying mechanisms of lncRNAs, which hold promise as potential biomarkers and therapeutic targets for cardiovascular conditions. The knowledge imparted in this review may prove valuable in guiding the design of future investigations and furthering the understanding of lncRNAs as diagnostic, prognostic, and therapeutic biomarkers for cardiovascular diseases.

Blood pressure responsiveness to resistance training in the hypertensive older adult: a randomized controlled study

Different lifestyle changes have been employed to improve clinical hypertension. However, there is scarce evidence on the blood pressure responsiveness to resistance training (RT) in hypertensive older adults. Consequently, little is known about some participants clinically reducing blood pressure and others not. Thus, we investigate the effects and responsiveness of RT on blood pressure in hypertensive older adults. We secondarily evaluated the biochemical risk factors for cardiovascular disease and functional performance. Older participants with hypertension were randomly assigned into RT (n = 27) and control group (n = 25). Blood pressure, functional performance (timed up and go, handgrip strength, biceps curl and sit-to-stand), fasting glucose, and lipid profiles were evaluated preintervention and postintervention. The statistic was performed in a single-blind manner, the statistician did not know who was the control and RT. RT was effective in reducing systolic blood pressure (SBP) (pre 135.7 ± 14.7; post 124.7 ± 11.0; P  < 0.001) and the responses to RT stimuli varied noticeably between hypertensive older adults after 12 weeks. For example, 13 and 1 responders displayed a minimal clinical important difference for SBP attenuation (10.9 mmHg) in the RT and control groups, respectively. RT improved the functional performance of older people with hypertension, while no differences were found in biochemical parameters (triglycerides, HDL, LDL, fasting glucose) after 12 weeks. In conclusion, responses to RT stimuli varied noticeably between hypertensive individuals and RT was effective in reducing SBP.

The Regulatory Role of MicroRNAs in Obesity and Obesity-Derived Ailments

Obesity is a condition that is characterized by the presence of excessive adipose tissue in the body. Obesity has become one of the main health concerns worldwide since it can lead to other chronic ailments, such as type 2 diabetes or fatty liver disease, and it could be an aggravating factor in infections. MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate gene expression and can play an important role in controlling crucial biological processes involved in the onset of obesity, such as lipogenesis, adipogenesis, lipid metabolism, or the regulation of cytokines and chemokines. Moreover, chemical compounds present in food or food packaging can alter miRNA expression and regulate the aforementioned biological mechanisms related to diabetes onset and progression. Furthermore, therapies, such as bariatric surgery and aerobic exercise training, can also influence the expression profile of miRNAs in obesity. Therefore, the present review provides insight into the current research on the role of miRNAs in obesity and obesity-derived ailments, intending to develop novel therapies to effectively manage these disorders.

Tracking Biomarker Responses to Exercise in Hypertension

PURPOSE OF REVIEW

Strong evidence is evolving that physical exercise prevents hypertension and reduces blood pressure in patients with pre- and manifest HTN. Yet, identifying and confirming the effectiveness of exercise are challenging. Herein, we discuss conventional and novel biomarkers such as extracellular vesicles (EVs) which may track responses to HTN before and after exercise.

RECENT FINDINGS

Evolving data shows that improved aerobic fitness and vascular function as well as lowered oxidative stress, inflammation, and gluco-lipid toxicity are leading biomarkers considered to promote HTN, but they explain only about a half of the pathophysiology. Novel biomarkers such as EVs or microRNA are providing additional input to understand the complex mechanisms involved in exercise therapy for HTN patients. Conventional and novel biomarkers are needed to fully understand the integrative "cross-talk" between tissues to regulate vasculature physiology for blood pressure control. These biomarker studies will lead to more specific disease markers and the development of even more personalized therapy in this field. However, more systematic approaches and randomized controlled trials in larger cohorts are needed to assess exercise effectiveness across the day and with different exercise types.

Exercise Training-Induced MicroRNA Alterations with Protective Effects in Cardiovascular Diseases

Exercise training (ET) is an important non-drug adjuvant therapy against many human diseases, including cardiovascular diseases. The appropriate ET intensity induces beneficial adaptions and improves physiological function and cardiopulmonary fitness. The mechanisms of exercise-induced cardioprotective effects are still not fully understood. However, mounting evidence suggest that microRNAs (miRNAs) play crucial role in this process and are essential in responding to exercise-stress and mediating exercise-protective effects. Thus, this review summarizes the biogenesis of miRNAs, the mechanism of miRNA action, and specifically the miRNAs involved in exercise-induced cardio-protection used as therapeutic targets for treating cardiovascular diseases.

The crosstalk among autophagy, apoptosis, and pyroptosis in cardiovascular disease

In recent years, the mechanism of cell death has become a hotspot in research on the pathogenesis and treatment of cardiovascular disease (CVD). Different cell death modes, including autophagy, apoptosis, and pyroptosis, are mosaic with each other and collaboratively regulate the process of CVD. This review summarizes the interaction and crosstalk of key pathways or proteins which play a critical role in the entire process of CVD and explores the specific mechanisms. Furthermore, this paper assesses the interrelationships among these three cell deaths and reviews how they regulate the pathogenesis of CVD. By understanding how these three cell death modes go together we can learn about the pathogenesis of CVD, which will enable us to identify new targets for preventing, controlling, and treating CVD. It will not only reduce mortality but also improve the quality of life.

Inter-individual variations in response to aerobic and resistance training in hypertensive older adults

BACKGROUND

Hemodynamic responses to physical training are not homogenous and uniform, and considerable inter-individual variations in the blood pressure of hypertensive individuals are noted in both aerobic and resistance training protocols. In this context, this study aimed to evaluate the effects of resistance and aerobic exercise on the blood pressure responses of hypertensive older adults.

METHODS

Groups were randomly divided into resistance training, n = 20; aerobic training, n = 20; control group, n = 21). After the first intervention period (12 weeks), individuals underwent a washout period (six detraining weeks), followed by a second intervention. This process is called the 'cross-over' model, where individuals who performed the aerobic exercise protocol also performed resistance training and vice-versa, constituting another 12 weeks of intervention. Blood pressure, functional performance, glycated hemoglobin and lipid profiles were evaluated preintervention and postintervention.

RESULTS

Varying responses to resistance training or aerobic training stimuli were observed in the hypertensive older adult participants. Both resistance training (pre 133.2 ± 14.1; post 122.4 ± 7.3; P < 0.05) and aerobic training (pre 134.2 ± 14.4; post 123 ± 9.4; P < 0.0.5) were effective in decreasing SBP, but only aerobic training (pre 9955.3 ± 1769.4; post 8800.9 ± 1316.1; P < 0.05) resulted in a decreased double product, and only the resistance training group improved functional performance.

CONCLUSION

Responses to resistance training or aerobic training stimuli varied noticeably between hypertensive older adults and both resistance training and aerobic training were effective in reducing SBP. This knowledge may be useful in providing individually tailored exercise prescriptions for hypertensive older adults.

The association between steps per day and blood pressure in children

Lower levels of physical activity are associated with an increased overall cardiometabolic risk, as well as the risk or being overweight. It is difficult to determine the optimal level of physical activity that protects the needs of children and young people. Studies on the required number of steps, as well as approximating the daily volume of physical activity, are gaining increasing credibility in research and practice. Researchers propose a "rule" of ≥ 11,500 steps per day, for children and teenagers of both sexes. The aim of the study was to assess whether 11,500 steps a day is sufficient to maintain normal blood pressure among children and adolescents. 1002 children and adolescents aged 4–15 were included in the study. To assess physical activity, measured in the number of steps per day, the Actigraph accelerometer wGT3X-BT was used. The normal number of steps was defined as greater than or equal to 11,500 steps per day for children and teenagers, for both girls and boys. In the entire study group, a significantly lower risk of hypertension was observed when the number of steps was normal (OR is 0.45 and the upper confidence limit for OR is 0.71). The study confirmed the beneficial protective role of physical activity against hypertension in older children and adolescents. However, it should be emphasized that no such relationship has been demonstrated in the case of preschool children. The presented norms of the number of steps should be promoted to the wider community to make prevention of cardiovascular diseases even more effective.

Effect of Combined Endurance Training and MitoQ on Cardiac Function and Serum Level of Antioxidants, NO, miR-126, and miR-27a in Hypertensive Individuals

Objectives

Hypertension (HTN) is one of the most important risk factors for cardiovascular diseases. Despite advances in treatment and control of HTN, the prevalence of HTN is still increasing. MitoQ is a supplement that acts on mitochondria and attenuates reactive oxygen species (ROS), which plays an important role in cardiovascular health. miRNAs play an important role in the pathophysiology of HTN. We evaluated the effects of MitoQ supplementation and endurance training (ET), alone and in combination, on functional indices of the heart and serum levels of miR-126, miR-27a, antioxidants, and NO, in patients with HTN.

Methods

In a double-blind randomized clinical trial, 52 male participants (age 40-55 years) were randomly divided into four groups (n = 13) of placebo, MitoQ (20 mg/day, oral), ET (cycle ergometer, moderate intensity, 40-60% VO₂ peak, heart rate 120-140 b/min, 45 min a day, three days/week for six weeks), and MitoQ+ET. Cardiac function indices were assessed by echocardiography before and after interventions.

Results

Systolic blood pressure (SBP) significantly decreased in all intervention groups (P < 0.001) while DBP (P < 0.01) and LV hypertrophy (P < 0.05) were significantly decreased only in the MitoQ+ET group. Serum levels of SOD, GPx, and NO and the level of miR-126 significantly increased in all treatment groups, while miR-27a reduced in the ET (P < 0.05) and MitoQ+ET (P < 0.01) groups.

Conclusions

Compared to MitoQ and ET alone, their combination has more prominent improving effects on cardiac health and amelioration of BP in the patients with HTN. These effects are through miR-126 and miR-27a modulation and ameliorating mitochondrial ROS production.

Effects of different types of exercise training on angiogenic responses in the left ventricular muscle of aged rats

BACKGROUND

We evaluated angiogenic responses in the left ventricular muscle and aerobic capacity according to exercise type (aerobic, resistance, combined) in aged rats.

METHODS

In total, 24 male Sprague-Dawley rats (100 weeks old) were used. To investigate the effect of regular training, the rats were divided into non-exercise (NE), aerobic exercise (AE), resistance exercise (RE), and combined exercise (CE) groups (six rats per group). Regular training tailored to each exercise type was performed for 8 weeks (five times a week, 1 h per day). After 8 weeks of training, aerobic capacity was evaluated by a treadmill running test. Left ventricular muscle tissue was collected and the protein levels of angiogenesis indicators (eNOS, HIF-1α, PGC-1α, VEGF, FLK-1, Ang-1, Ang-2) were analyzed by Western blotting. Capillaries were observed by immunohistochemical staining for CD31.

RESULTS

Body weight, heart weight, and heart/body weight ratio showed no difference among the groups. The AE and CE groups showed higher treadmill running capacity than the NE and RE groups. The eNOS, VEGF, HIF-1α, PGC-1α, and Ang-2 protein levels were significantly higher in the AE than NE group. The PGC-1α and FLK-1 protein levels were significantly higher in the RE than NE group. In addition, in the CE group, the eNOS, FLK-1, and PGC-1α protein levels were significantly higher than in the NE group. Expression of CD31 in cardiac tissue was higher in the AE and CE groups than in the other groups.

CONCLUSIONS

Taken together, the results suggest that regular exercise training, irrespective of exercise type, might improve cardiovascular function by inducing angiogenic responses in the aged myocardium; however, AE may be the most effective.

MicroRNAs Regulating Renin-Angiotensin-Aldosterone System, Sympathetic Nervous System and Left Ventricular Hypertrophy in Systemic Arterial Hypertension

MicroRNAs are small non-coding RNAs that regulate gene and protein expression. MicroRNAs also regulate several cellular processes such as proliferation, differentiation, cell cycle, apoptosis, among others. In this context, they play important roles in the human body and in the pathogenesis of diseases such as cancer, diabetes, obesity and hypertension. In hypertension, microRNAs act on the renin-angiotensin-aldosterone system, sympathetic nervous system and left ventricular hypertrophy, however the signaling pathways that interact in these processes and are regulated by microRNAs inducing hypertension and the worsening of the disease still need to be elucidated. Thus, the aim of this review is to analyze the pattern of expression of microRNAs in these processes and the possible associated signaling pathways.

Interleukin-1β in Multifactorial Hypertension: Inflammation, Vascular Smooth Muscle Cell and Extracellular Matrix Remodeling, and Non-Coding RNA Regulation

The biological activities of interleukins, a group of circulating cytokines, are linked to the immuno-pathways involved in many diseases. Mounting evidence suggests that interleukin-1β (IL-1β) plays a significant role in the pathogenesis of various types of hypertension. In this review, we summarized recent findings linking IL-1β to systemic arterial hypertension, pulmonary hypertension, and gestational hypertension. We also outlined the new progress in elucidating the potential mechanisms of IL-1β in hypertension, focusing on it's regulation in inflammation, vascular smooth muscle cell function, and extracellular remodeling. In addition, we reviewed recent studies that highlight novel findings examining the function of non-coding RNAs in regulating the activity of IL-1β and its associated proteins in the setting of hypertension. The information collected in this review provides new insights into understanding the pathogenesis of hypertension and could lead to the discovery of new anti-hypertensive therapies to combat this highly prevalent disease.

Molecular mechanisms underlying fructose-induced cardiovascular disease: exercise, metabolic pathways and microRNAs

NEW FINDINGS

What is the central question of this study? What are the mechanisms underlying the cardiac protective effect of aerobic training in the progression of a high fructose-induced cardiometabolic disease in Wistar rats? What is the main finding and its importance? At the onset of cardiovascular disease, aerobic training activates the p-p70S6K, ERK and IRβ-PI3K-AKT pathways, without changing the miR-126 and miR-195 levels, thereby providing evidence that aerobic training modulates the insulin signalling pathway. These data contribute to the understanding of the molecular cardiac changes that are associated with physiological left ventricular hypertrophy during the development of a cardiovascular disease.

ABSTRACT

During the onset of cardiovascular disease (CVD), disturbances in myocardial vascularization, cell proliferation and protein expression are observed. Aerobic training prevents CVD, but the underlying mechanisms behind left ventricle (LV) hypertrophy are not fully elucidated. The aim of this study was to investigate the mechanisms by which aerobic training protects the heart from LV hypertrophy during the onset of fructose-induced cardiometabolic disease. Male Wistar rats were allocated to four groups (n = 8/group): control sedentary (C), control training (CT), fructose sedentary (F) and fructose training (FT). The C and CT groups received drinking water, and the F and FT groups received d-fructose (10% in water). After 2 weeks, the CT and FT rats were assigned to a treadmill training protocol at moderate intensity for 8 weeks (60 min/day, 4 days/week). After 10 weeks, LV morphological remodelling, cardiomyocyte apoptosis, microRNAs and the insulin signalling pathway were investigated. The F group had systemic cardiometabolic alterations, which were normalised by aerobic training. The LV weight increased in the FT group, myocardium vascularisation decreased in the F group, and the cardiomyocyte area increased in the CT, F and FT groups. Regarding protein expression, total insulin receptor β-subunit (IRβ) decreased in the F group; phospho (p)-IRβ and phosphoinositide 3-kinase (PI3K) increased in the FT group; total-AKT and p-AKT increased in all of the groups; p-p70S6 kinase (p70S6K) protein was higher in the CT group; and p-extracellular signal-regulated kinase (ERK) increased in the CT and FT groups. MiR-126, miR-195 and cardiomyocyte apoptosis did not differ among the groups. Aerobic training activates p-p70S6K and p-ERK, and during the onset of a CVD, it can activate the IRβ-PI3K-AKT pathway.

Cardiac T-Tubule cBIN1-Microdomain, a Diagnostic Marker and Therapeutic Target of Heart Failure

Since its first identification as a cardiac transverse tubule (t-tubule) protein, followed by the cloning of the cardiac isoform responsible for t-tubule membrane microdomain formation, cardiac bridging integrator 1 (cBIN1) and its organized microdomains have emerged as a key mechanism in maintaining normal beat-to-beat heart contraction and relaxation. The abnormal remodeling of cBIN1-microdomains occurs in stressed and diseased cardiomyocytes, contributing to the pathophysiology of heart failure. Due to the homeostatic turnover of t-tubule cBIN1-microdomains via microvesicle release into the peripheral circulation, plasma cBIN1 can be assayed as a liquid biopsy of cardiomyocyte health. A new blood test cBIN1 score (CS) has been developed as a dimensionless inverse index derived from plasma cBIN1 concentration with a diagnostic and prognostic power for clinical outcomes in stable ambulatory patients with heart failure with reduced or preserved ejection fraction (HFrEF or HFpEF). Recent evidence further indicates that exogenous cBIN1 introduced by adeno-associated virus 9-based gene therapy can rescue cardiac contraction and relaxation in failing hearts. The therapeutic potential of cBIN1 gene therapy is enormous given its ability to rescue cardiac inotropy and provide lusitropic protection in the meantime. These unprecedented capabilities of cBIN1 gene therapy are shifting the current paradigm of therapy development for heart failure, particularly HFpEF.

Dexamethasone Does Not Inhibit Treadmill Training-Induced Angiogenesis in Myocardium: Role of MicroRNA-126 Pathway

Dexamethasone (DEX) has important anti-inflammatory activities; however, it induces hypertension and skeletal muscle microcirculation rarefaction. Nevertheless, nothing is known about DEX outcomes on cardiac microcirculation. By contrast, exercise training prevents skeletal and cardiac microvessel loss because of microRNA expression and a better balance between their related angiogenic and apoptotic proteins in spontaneously hypertensive rats. The purpose of this study was to investigate whether DEX and/or exercise training could induce microRNA alterations leading to cardiac angiogenesis or microvascular rarefaction. Animals performed 8 weeks of exercise training and were treated with DEX (50 μg/kg per day, subcutaneously) for 14 days. Cardiovascular parameters were measured, and the left ventricle muscle was collected for analyses. DEX treatment increased arterial pressure and did not cause cardiac microcirculation rarefaction. Treadmill training prevented the DEX-induced increase in arterial pressure. In addition, training, regardless of DEX treatment, increased microRNA-126 expression, phospho-protein kinase B/protein kinase B, and endothelial nitric oxide synthase levels associated with cardiac angiogenesis. In conclusion, this study suggests, for the first time, that treadmill training induces myocardial angiogenesis because of angiogenic pathway improvement associated with an increase in microRNA-126. Furthermore, DEX, per se, did not cause capillary density alterations and did not attenuate cardiac angiogenesis induced by training.

In Mice Subjected to Chronic Stress, Exogenous cBIN1 Preserves Calcium-Handling Machinery and Cardiac Function

Heart failure is an important, and growing, cause of morbidity and mortality. Half of patients with heart failure have preserved ejection fraction, for whom therapeutic options are limited. Here we report that cardiac bridging integrator 1 gene therapy to maintain subcellular membrane compartments within cardiomyocytes can stabilize intracellular distribution of calcium-handling machinery, preserving diastolic function in hearts stressed by chronic beta agonist stimulation and pressure overload. This study identifies that maintenance of intracellular architecture and, in particular, membrane microdomains at t-tubules, is important in the setting of sympathetic stress. Stabilization of membrane microdomains may be a pathway for future therapeutic development.

MicroRNA-126 upregulation, induced by training, plays a role in controlling microcirculation in dexamethasone treated rats

Microcirculation maintenance is associated with microRNAs. Nevertheless, the role of microRNAs induced by training in preventing dexamethasone (DEX)-induced microvascular rarefaction remains unknown. The study aim was to investigate if training-induced microRNAs are able to improve microcirculation proteins and prevent DEX-induced microvascular rarefaction. Rats underwent training for 8 weeks and then were treated with DEX (50 μg/kg per day, s.c.) for 14 days. Arterial pressure was measured and tibialis anterior (TA) muscle was collected for analyses. DEX induced hypertension concomitantly with capillary density loss (CD, -23.9%) and decrease of VEGF (-43.0%), p-AKT/AKT (-39.6%) and Bcl-2 (-23.0%) and an increase in caspase-3-cleaved protein level (+34.0%) in TA muscle. Training upregulated microRNA-126 expression (+13.1%), prevented VEGF (+61.4%), p-AKT/AKT (+37.7%), Bcl-2 (+7.7%) decrease and caspase-3-cleaved (-23.1%) increase associated with CD (+54.7%) reduction and hypertension prevention. MiRNA-126 upregulation, induced by training, plays a role in controlling microcirculation, which may be a potential target against DEX-induced microvascular rarefaction.

Training counteracts DEX-induced microvascular rarefaction by improving the balance between apoptotic and angiogenic proteins

This work investigated the mechanisms induced by exercise training that may contribute to attenuate dexamethasone (DEX)-induced microvascular rarefaction and hypertension. Wistar rats underwent training protocol or were kept sedentary for 8 weeks. Dexamethasone was administered during the following 14-days and hemodynamic parameters were recorded at the end. Capillary density (CD) and capillary-to-fiber ratio (C:F ratio) were obtained in soleus muscle (SOL). Also, vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor-2 (VEGFR-2), endothelial nitric oxide synthase (eNOS), B-cell lymphoma 2 (Bcl-2), Bcl-2-like protein 4 (Bax), p-BAX and caspase-3 cleaved protein levels were analyzed. DEX treatment significantly increased blood pressure (+14%), which was associated with reduced C:F ratio (-41.0%) and CD (-43.1%). Reduction of vessel density was associated with decreased VEGF (-15.6%), VEGFR-2 (-14.6%), Bcl-2 (-18.4%), Bcl-2/Bax ratio (-29.0%) and p-Bax/Bax (-25.4%), and also with increased caspase-3 cleaved protein level (25%). Training, on the other hand, prevented microvessels loss by mitigating all proteins changes induced by DEX. In addition, angiogenic and apoptotic proteins were significantly correlated with CD, which, in turn, was associated with blood pressure. Therefore, we may point out that exercise training is a good strategy to attenuate DEX-induced microvascular rarefaction in soleus muscle and this response involves a better balance between apoptotic and angiogenic proteins, which may contribute for the attenuation of hypertension.

Effects of aerobic and inspiratory training on skeletal muscle microRNA-1 and downstream-associated pathways in patients with heart failure

BACKGROUND

The exercise intolerance in chronic heart failure with reduced ejection fraction (HFrEF) is mostly attributed to alterations in skeletal muscle. However, the mechanisms underlying the skeletal myopathy in patients with HFrEF are not completely understood. We hypothesized that (i) aerobic exercise training (AET) and inspiratory muscle training (IMT) would change skeletal muscle microRNA-1 expression and downstream-associated pathways in patients with HFrEF and (ii) AET and IMT would increase leg blood flow (LBF), functional capacity, and quality of life in these patients.

METHODS

Patients age 35 to 70 years, left ventricular ejection fraction (LVEF) ≤40%, New York Heart Association functional classes II-III, were randomized into control, IMT, and AET groups. Skeletal muscle changes were examined by vastus lateralis biopsy. LBF was measured by venous occlusion plethysmography, functional capacity by cardiopulmonary exercise test, and quality of life by Minnesota Living with Heart Failure Questionnaire. All patients were evaluated at baseline and after 4 months.

RESULTS

Thirty-three patients finished the study protocol: control (n = 10; LVEF = 25 ± 1%; six males), IMT (n = 11; LVEF = 31 ± 2%; three males), and AET (n = 12; LVEF = 26 ± 2%; seven males). AET, but not IMT, increased the expression of microRNA-1 (P = 0.02; percent changes = 53 ± 17%), decreased the expression of PTEN (P = 0.003; percent changes = -15 ± 0.03%), and tended to increase the p-AKT^ser473 /AKT ratio (P = 0.06). In addition, AET decreased HDAC4 expression (P = 0.03; percent changes = -40 ± 19%) and upregulated follistatin (P = 0.01; percent changes = 174 ± 58%), MEF2C (P = 0.05; percent changes = 34 ± 15%), and MyoD expression (P = 0.05; percent changes = 47 ± 18%). AET also increased muscle cross-sectional area (P = 0.01). AET and IMT increased LBF, functional capacity, and quality of life. Further analyses showed a significant correlation between percent changes in microRNA-1 and percent changes in follistatin mRNA (P = 0.001, rho = 0.58) and between percent changes in follistatin mRNA and percent changes in peak VO₂ (P = 0.004, rho = 0.51).

CONCLUSIONS

AET upregulates microRNA-1 levels and decreases the protein expression of PTEN, which reduces the inhibitory action on the PI3K-AKT pathway that regulates the skeletal muscle tropism. The increased levels of microRNA-1 also decreased HDAC4 and increased MEF2c, MyoD, and follistatin expression, improving skeletal muscle regeneration. These changes associated with the increase in muscle cross-sectional area and LBF contribute to the attenuation in skeletal myopathy, and the improvement in functional capacity and quality of life in patients with HFrEF. IMT caused no changes in microRNA-1 and in the downstream-associated pathway. The increased functional capacity provoked by IMT seems to be associated with amelioration in the respiratory function instead of changes in skeletal muscle. ClinicalTrials.gov (Identifier: NCT01747395).

Exercise training prevents obesity-associated disorders: Role of miRNA-208a and MED13

Exercise training (ET) has been established as an important treatment for obesity, since it counteracts aberrant cardiac metabolism and weight gain; however, underlying mechanisms remain to be further determined. MicroRNAs (miRNAs) inhibit protein expression by base-pairing with the 3' UTRs of mRNA targets. MiRNA-208a is a cardiac-specific miRNA that regulates β-MHC content and systemic energy homeostasis via MED13. We investigated whether ET regulates the cardiac miRNA-208a and its target MED13, reducing the weight gain and β-MHC expression in obese Zucker rats (OZR). OZR (n = 11) and Lean (L, n = 10) male rats were assigned into 4 groups: OZR, trained OZR (OZRT), L and trained L (LT). Swimming ET consisted of 60 min of duration, 1x/day, 5x/week/10 weeks. MiRNA and gene expression were analyzed by real-time PCR and protein levels by western blot. Resting bradycardia was observed in trained groups. ET reduced weight gain, retroperitoneal fat weight and adipocyte cell size in OZRT compared with OZR group. Cardiac miRNA-208a levels increased 57% in OZR paralleled with a decrease of 39% in MED13 protein levels compared with L group. In contrast, ET corrected the cardiac miRNA-208a and MED13 levels in OZRT compared with L group. Furthermore, ET reduced the increased cardiac mass and normalized β-MHC protein levels caused by obesity. These results suggest that ET can prevent weight gain and pathological cardiac hypertrophy via increased of cardiac MED13 by the regulation of miRNA-208a. Therefore, miRNA-208a can be used as potential therapeutic target for metabolic and cardiac disorders.

Exercise Training-Induced Changes in MicroRNAs: Beneficial Regulatory Effects in Hypertension, Type 2 Diabetes, and Obesity

MicroRNAs are small non-coding RNAs that regulate gene expression post-transcriptionally. They are involved in the regulation of physiological processes, such as adaptation to physical exercise, and also in disease settings, such as systemic arterial hypertension (SAH), type 2 diabetes mellitus (T2D), and obesity. In SAH, microRNAs play a significant role in the regulation of key signaling pathways that lead to the hyperactivation of the renin-angiotensin-aldosterone system, endothelial dysfunction, inflammation, proliferation, and phenotypic change in smooth muscle cells, and the hyperactivation of the sympathetic nervous system. MicroRNAs are also involved in the regulation of insulin signaling and blood glucose levels in T2D, and participate in lipid metabolism, adipogenesis, and adipocyte differentiation in obesity, with specific microRNA signatures involved in the pathogenesis of each disease. Many studies report the benefits promoted by exercise training in cardiovascular diseases by reducing blood pressure, glucose levels, and improving insulin signaling and lipid metabolism. The molecular mechanisms involved, however, remain poorly understood, especially regarding the participation of microRNAs in these processes. This review aimed to highlight microRNAs already known to be associated with SAH, T2D, and obesity, as well as their possible regulation by exercise training.

Cardiovascular disease-related miRNAs expression: potential role as biomarkers and effects of training exercise

Cardiovascular diseases (CVDs) are one of the most important causes of mortality worldwide, therefore the need of effective preventive strategies is imperative. Aging is associated with significant changes in both cardiovascular structure and function that lower the threshold for clinical signs and symptoms, making older people more susceptible to CVDs morbidity and mortality. microRNAs (miRNAs) modulate gene expression at post-transcriptional level and increasing evidence has shown that miRNAs are involved in cardiovascular physiology and in the pathogenesis of CVDs. Physical activity is recommended by the medical community and the cardiovascular benefits of exercise are multifactorial and include important systemic effects on skeletal muscle, the peripheral vasculature, metabolism, and neuroendocrine systems, as well as beneficial modifications within the myocardium itself. In this review we describe the role of miRNAs and their dysregulation in several types of CVDs. We provide an overview of miRNAs in CVDs and of the effects of physical activity on miRNA regulation involved in both cardiovascular pathologies and age-related cardiovascular changes and diseases. Circulating miRNAs in response to acute and chronic sport exercise appear to be modulated following training exercise, and may furthermore serve as potential biomarkers for CVDs and different age-related CVDs.

Role of MicroRNA in Endothelial Dysfunction and Hypertension

Purpose of Review

Hypertension is either a cause or a consequence of the endothelial dysfunction and a major risk factor for cardiovascular disease (CVD). In vitro and in vivo studies established that microRNAs (miRNAs) are decisive for endothelial cell gene expression and function in various pathological conditions associated with CVD.

This review provides an overview of the miRNA role in controlling the key connections between endothelial dysfunction and hypertension.

Recent Findings

Herein we summarize the present understanding of mechanisms underlying hypertension and its associated endothelial dysfunction as well as the miRNA role in endothelial cells with accent on the modulation of renin-angiotensin-aldosterone-system, nitric oxide, oxidative stress and on the control of vascular inflammation and angiogenesis in relation to endothelial dysfunction in hypertension. In particular, latest insights in the identification of endothelial-specific microRNAs and their targets are added to the understanding of miRNA significance in hypertension.

Summary

This comprehensive knowledge of the role of miRNAs in endothelial dysfunction and hypertension and of molecular mechanisms proposed for miRNA actions may offer novel diagnostic biomarkers and therapeutic targets for controlling hypertension-associated endothelial dysfunction and other cardiovascular complications.

Exercise Training Restores the Cardiac Microrna-16 Levels Preventing Microvascular Rarefaction in Obese Zucker Rats

OBJECTIVE

To evaluate the effects of aerobic exercise training (AET) on cardiac miRNA-16 levels and its target gene VEGF related to microvascular rarefaction in obese Zucker rats (OZR).

METHODS

OZR (n = 11) and lean (L; n = 10) male rats were assigned into 4 groups: OZR, trained OZR (OZRT), L and trained L (LT). Swimming exercise training lasted 60 min, 1×/day/10 weeks, with 4% body weight workload. Cardiac angiogenesis was assessed by histological analysis (periodic acid-Schiff) by calculating the capillary/fiber ratio. The protein expressions of VEGF, VEGFR2, and CD31 were evaluated by western blot. The expression of miRNA-16 was evaluated by real-time PCR.

RESULTS

Heart rate decreased in the trained groups compared to sedentary groups. The cardiac capillary/fiber ratio was reduced in OZR compared to L, LT and OZRT groups, indicating that aerobic exercise training (AET) was capable of reversing the microvascular rarefaction in the obese animals. miRNA-16 expression was increased in OZR compared to L, LT and OZRT. In contrast, its target, VEGF protein expression was 24% lower in OZR compared to L group, which has been normalized in OZRT group. VEGFR2 protein expression was increased in trained groups compared to their controls. CD31, a endothelial cells marker, showed increased expression in OZRT compared to OZR, indicating greater vascularization in OZRT group.

CONCLUSION

AET induced cardiac angiogenesis in obese animals. This revascularization is associated with a decrease in miRNA-16 expression permissive for increased VEGF protein expression, suggesting a mechanism for potential therapeutic application in vascular diseases.

Telomeres, Aging and Exercise: Guilty by Association?

Telomeres are repetitive tandem DNA sequences that cap chromosomal ends protecting genomic DNA from enzymatic degradation. Telomeres progressively shorten with cellular replication and are therefore assumed to correlate with biological and chronological age. An expanding body of evidence suggests (i) a predictable inverse association between telomere length, aging and age-related diseases and (ii) a positive association between physical activity and telomere length. Both hypotheses have garnered tremendous research attention and broad consensus; however, the evidence for each proposition is inconsistent and equivocal at best. Telomere length does not meet the basic criteria for an aging biomarker and at least 50% of key studies fail to find associations with physical activity. In this review, we address the evidence in support and refutation of the putative associations between telomere length, aging and physical activity. We finish with a brief review of plausible mechanisms and potential future research directions.

Epigenetic effects of physical activity in elderly patients with cardiovascular disease

Cardiovascular disease (CVD) is an important public health problem affecting especially the elderly. Over the past 20years, an increasing number of studies have examined its underlying pathophysiological mechanisms and new therapies are continually being discovered. However, despite considerable progress in CVD management, mortality and morbidity remain a major healthcare concern, and frequent hospital admissions compromise the daily life and social activities of these patients. Physical activity has emerged as an important non-pharmacological adjunctive therapy for CVD in older patients, especially for heart failure patients, exerting its beneficial effects on mortality, morbidity, and functional capacity. The mechanisms underlying the cardiovascular benefits of exercise are not wholly clear. Mounting evidence suggest that epigenetic modifications, such as DNA methylation, histone post-translational modifications (hPTMs) and non-coding RNA, especially microRNAs (miRNAs), may be induced by physical activity. Recently, a number of miRNAs have been identified as key players in gene expression modulation by exercise. MiRNAs are synthesized by living cells and actively released into the bloodstream through different shuttles. The epigenetic information, thus carried and delivered, is involved in the interplay between environmental factors, including physical activity, and individual genetic make-up. We review and discuss the effects of exercise on age-related CVDs, focusing on circulating miRNA (c-miRNAs) modulation. Epigenetic mechanisms may have clinical relevance in CVD prevention and management; since they can be modified, insights into the implications of lifestyle-related epigenetic changes in CVD etiology may help develop therapeutic protocols of exercise training that can be suitable and effective for elderly patients.

Role of miR-128 in hypertension-induced myocardial injury

The present study aimed to investigate the role and mechanism of micro RNA (miR)-128 in hypertension-induced myocardial injury. The peripheral blood of patients with hypertension was collected and the expression of miR-128 was detected using fluorescence reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Primary myocardial cells isolated from rat in vitro were cultured under conditions of hypoxia and glucose deprivation, and miR-128 expression was measured by RT-qPCR. The expression of c-Met protein was measured using western blot analysis and the apoptosis of transfected cells was measured by flow cytometry in rat myocardial cells following transfection with miR-128 mimics or c-Met siRNA. A luciferase assay was applied to assess the binding of miR-128 to c-Met mRNA. miR-128 expression was significantly higher in hypertension patients compared with controls (P<0.05). miR-128 expression was higher in patients with stage III/IV hypertension compared with patients with stage II hypertension. Similarly, miR-128 expression in primary cardiomyocytes cultured under deprivation of oxygen and glucose increased with the culture time and reached a peak at 12 h. c-Met expression decreased significantly (P<0.05) and the ratio of apoptotic cells increased significantly (P<0.05), following transfection of miR-128 mimics. The number of apoptotic cells also increased when c-Met expression was knocked down by siRNA. The dual luciferase assay indicated that fluorescence intensity decreased significantly in miR-128 mimics and wild type c-Met group (P<0.05), indicating that miR-128 can directly target c-Met. Therefore, the results of the current study suggest that miR-128 may promote myocardial cell injury by regulating c-Met expression.

miR-181b regulates vascular stiffness age dependently in part by regulating TGF-β signaling

BACKGROUND

Endothelial dysfunction and arterial stiffening play major roles in cardiovascular diseases. The critical role for the miR-181 family in vascular inflammation has been documented. Here we tested whether the miR-181 family can influence the pathogenesis of hypertension and vascular stiffening.

METHODS AND RESULTS

qPCR data showed a significant decrease in miR-181b expression in the aorta of the older mice. Eight miR-181a1/b1-/- mice and wild types (C57BL6J:WT) were followed weekly for pulse wave velocity (PWV) and blood pressure measurements. After 20 weeks, the mice were tested for endothelial function and aortic modulus. There was a progressive increase in PWV and higher systolic blood pressure in miR-181a1/b1-/- mice compared with WTs. At 21 weeks, aortic modulus was significantly greater in the miR-181a1/b1-/- group, and serum TGF-β was found to be elevated at this time. A luciferase reporter assay confirmed miR-181b targets TGF-βi (TGF-β induced) in the aortic VSMCs. In contrast, wire myography revealed unaltered endothelial function along with higher nitric oxide production in the miR-181a1/b1-/- group. Cultured VECs and VSMCs from the mouse aorta showed more secreted TGF-β in VSMCs of the miR-181a1/b1-/- group; whereas, no change was observed from VECs. Circulating levels of angiotensin II were similar in both groups. Treatment with losartan (0.6 g/L) prevented the increase in PWV, blood pressure, and vascular stiffness in miR-181a1/b1-/- mice. Immunohistochemistry and western blot for p-SMAD2/3 validated the inhibitory effect of losartan on TGF-β signaling in miR-181a1/b1-/- mice.

CONCLUSIONS

Decreased miR-181b with aging plays a critical role in ECM remodeling by removing the brake on the TGF-β, pSMAD2/3 pathway.

Blood pressure and expression of microRNAs in whole blood

Background

Blood pressure (BP) is a complex, multifactorial clinical outcome driven by genetic susceptibility, behavioral choices, and environmental factors. Many molecular mechanisms have been proposed for the pathophysiology of high BP even as its prevalence continues to grow worldwide, increasing morbidity and marking it as a major public health concern. To address this, we evaluated miRNA profiling in blood leukocytes as potential biomarkers of BP and BP-related risk factors.

Methods

The Beijing Truck Driver Air Pollution Study included 60 truck drivers and 60 office workers examined in 2008. On two days separated by 1–2 weeks, we examined three BP measures: systolic, diastolic, and mean arterial pressure measured at both pre- and post-work exams for blood NanoString nCounter miRNA profiles. We used covariate-adjusted linear mixed-effect models to examine associations between BP and increased miRNA expression in both pooled and risk factor-stratified analyses.

Results

Overall 43 miRNAs were associated with pre-work BP (FDR<0.05). In stratified analyses different but overlapping groups of miRNAs were associated with pre-work BP in truck drivers, high-BMI participants, and usual alcohol drinkers (FDR<0.05). Only four miRNAs were associated with post-work BP (FDR<0.05), in ever smokers.

Conclusion

Our results suggest that many miRNAs were significantly associated with BP in subgroups exposed to known hypertension risk factors. These findings shed light on the underlying molecular mechanisms of BP, and may assist with the development of a miRNA panel for early detection of hypertension.

Irisin Lowers Blood Pressure by Improvement of Endothelial Dysfunction via AMPK-Akt-eNOS-NO Pathway in the Spontaneously Hypertensive Rat

BACKGROUND

Exercise is a major nonpharmacological treatment for hypertension, but its underlying mechanisms are still not completely elucidated. Irisin, a polypeptide containing 112 amino acids, which is secreted mainly by skeletal muscle cells during exercise, exerts a protective role in metabolic diseases, such as diabetes mellitus and obesity. Because of the close relationship between irisin and metabolic diseases, we hypothesized that irisin may play a role in the regulation of blood pressure.

METHODS AND RESULTS

Blood pressures of male Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) were monitored through the carotid artery. Our study found that acute intravenous injection of irisin reduced blood pressure in SHRs, but not WKY rats. Irisin, by itself, had no direct vasorelaxing effect in phenylephrine-preconstricted mesenteric arteries from SHRs. However, irisin augmented the acetylcholine-induced vasorelaxation in mesenteric arteries from SHRs that could be reversed by Nω-nitro-l-arginine-methyl ester (L-NAME; 100 μmol/L), indicating a role of nitric oxide (NO) in this action. Indeed, irisin increased NO production and phosphorylation of endothelial nirtic oxide synthase (eNOS) in endothelial cells. 5'-AMP-activated protein kinase (AMPK) was involved in the vasorelaxing effect of irisin because compound C (20 μmol/L), an AMPK inhibitor, blocked the irisin-mediated increase in phosphorylation of eNOS and protein kinase B (Akt) in endothelial cells and vasodilation in mesenteric arteries.

CONCLUSIONS

We conclude that acute administration of irisin lowers blood pressure of SHRs by amelioration of endothelial dysfunction of the mesenteric artery through the AMPK-Akt-eNOS-NO signaling pathway.

Shear-Sensitive Genes in Aortic Valve Endothelium

SIGNIFICANCE

Currently, calcific aortic valve disease (CAVD) is only treatable through surgical intervention because the specific mechanisms leading to the disease remain unclear. In this review, we explore the forces and structure of the valve, as well as the mechanosensors and downstream signaling in the valve endothelium known to contribute to inflammation and valve dysfunction.

RECENT ADVANCES

While the valvular structure enables adaptation to dynamic hemodynamic forces, these are impaired during CAVD, resulting in pathological systemic changes. Mechanosensing mechanisms-proteins, sugars, and membrane structures-at the surface of the valve endothelial cell relay mechanical signals to the nucleus. As a result, a large number of mechanosensitive genes are transcribed to alter cellular phenotype and, ultimately, induce inflammation and CAVD. Transforming growth factor-β signaling and Wnt/β-catenin have been widely studied in this context. Importantly, NADPH oxidase and reactive oxygen species/reactive nitrogen species signaling has increasingly been recognized to play a key role in the cellular response to mechanical stimuli. In addition, a number of valvular microRNAs are mechanosensitive and may regulate the progression of CAVD.

CRITICAL ISSUES

While numerous pathways have been described in the pathology of CAVD, no treatment options are available to avoid surgery for advanced stenosis and calcification of the aortic valve. More work must be focused on this issue to lead to successful therapies for the disease.

FUTURE DIRECTIONS

Ultimately, a more complete understanding of the mechanisms within the aortic valve endothelium will lead us to future therapies important for treatment of CAVD without the risks involved with valve replacement or repair. Antioxid. Redox Signal. 25, 401-414.

Expression of the Mir-133 and Bcl-2 could be affected by swimming training in the heart of ovariectomized rats

OBJECTIVES

The beneficial and more potent role of exercise to prevent heart apoptosis in ovariectomized rats has been known. The aim of this study was to examine the effects of swimming training on cardiac expression of Bcl-2, and Mir-133 levels and glycogen changes in the myocyte.

MATERIALS AND METHODS

Forty animals were separated into four groups as control, sham, ovariectomy (OVX) and ovariectomized group with 8 weeks swimming training (OVX.E). Training effects were evaluated by measuring lipid profiles, Bcl-2 and Mir-133 expression levels in the cardiac tissue. Grafts were analyzed by reverse transcription-polymerase chain reaction for Bcl-2 mRNA and Mir-133 and by Western blot for Bcl-2 protein.

RESULTS

Ovariectomy down-regulated Bcl-2 and Mir-133 expression levels in the cardiac tissue, and swimming training up-regulated their expression significantly (P<0.05).

CONCLUSION

Our results showed that regular exercise as a physical replacement therapy could prevent and improve the effects of estrogen deficiency in the cardia.

Microarray expression profiling and gene ontology analysis of long non-coding RNAs in spontaneously hypertensive rats and their potential roles in the pathogenesis of hypertension

Long non-coding RNAs (lncRNAs) have been demonstrated to be significant in numerous biological processes. Hypertension is a form of cardiovascular disease with at least one billion cases worldwide. The present study sought to compare the differential expression profiles of lncRNAs in the renal cortex of spontaneously hypertensive rats (SHRs) and normotensive Wistar‑Kyoto (WKY) rats. The ipsilateral renal cortex was obtained from 15‑week‑old SHRs and WKY rats whose blood pressures had been monitored. Total RNA was extracted using TRIzol, and lncRNAs and messenger RNAs were profiled by microarray and validated using fluorescent quantitative reverse transcription‑polymerase chain reaction. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the function of differentially expressed genes. Microarray analysis demonstrated that 145 lncRNAs were differentially expressed between SHRs and WKY rats. GO and KEGG pathway analysis indicated that these lncRNAs are involved in numerous biological processes. Thus, lncRNAs may contribute to the pathogenesis of hypertension.

Influence of Physical Activity on Hypertension and Cardiac Structure and Function

The global burden of hypertension is rising and accounts for substantial morbidity and mortality. Lifestyle factors such as diet and physical inactivity contribute to this burden, further highlighting the need for prevention efforts to curb this public health epidemic. Regular physical activity is associated with lower blood pressure, reduced cardiovascular risk, and cardiac remodeling. While exercise and hypertension can both be associated with the development of left ventricular hypertrophy (LVH), the cardiac remodeling from hypertension is pathologic with an associated increase in myocyte hypertrophy, fibrosis, and risk of heart failure and mortality, whereas LVH in athletes is generally non-pathologic and lacks the fibrosis seen in hypertension. In hypertensive patients, physical activity has been associated with paradoxical regression or prevention of LVH, suggesting a mechanism by which exercise can benefit hypertensive patients. Further studies are needed to better understand the mechanisms underlying the benefits of physical activity in the hypertensive heart.

Aerobic exercise training promotes physiological cardiac remodeling involving a set of microRNAs

Left ventricular (LV) hypertrophy is an important physiological compensatory mechanism in response to chronic increase in hemodynamic overload. There are two different forms of LV hypertrophy, one physiological and another pathological. Aerobic exercise induces beneficial physiological LV remodeling. The molecular/cellular mechanisms for this effect are not totally known, and here we review various mechanisms including the role of microRNA (miRNA). Studies in the heart, have identified antihypertrophic miRNA-1, -133, -26, -9, -98, -29, -378, and -145 and prohypertrophic miRNA-143, -103, -130a, -146a, -21, -210, -221, -222, -27a/b, -199a/b, -208, -195, -499, -34a/b/c, -497, -23a, and -15a/b. Four miRNAs are recognized as cardiac-specific: miRNA-1, -133a/b, -208a/b, and -499 and called myomiRs. In our studies we have shown that miRNAs respond to swimming aerobic exercise by 1) decreasing cardiac fibrosis through miRNA-29 increasing and inhibiting collagen, 2) increasing angiogenesis through miRNA-126 by inhibiting negative regulators of the VEGF pathway, and 3) modulating the renin-angiotensin system through the miRNAs-27a/b and -143. Exercise training also increases cardiomyocyte growth and survival by swimming-regulated miRNA-1, -21, -27a/b, -29a/c, -30e, -99b, -100, -124, -126, -133a/b, -143, -144, -145, -208a, and -222 and running-regulated miRNA-1, -26, -27a, -133, -143, -150, and -222, which influence genes associated with the heart remodeling and angiogenesis. We conclude that there is a potential role of these miRNAs in promoting cardioprotective effects on physiological growth.

Role of MicroRNAs in Renin-Angiotensin-Aldosterone System-Mediated Cardiovascular Inflammation and Remodeling

MicroRNAs are endogenous regulators of gene expression either by inhibiting translation or protein degradation. Recent studies indicate that microRNAs play a role in cardiovascular disease and renin-angiotensin-aldosterone system- (RAAS-) mediated cardiovascular inflammation, either as mediators or being targeted by RAAS pharmacological inhibitors. The exact role(s) of microRNAs in RAAS-mediated cardiovascular inflammation and remodeling is/are still in early stage of investigation. However, few microRNAs have been shown to play a role in RAAS signaling, particularly miR-155, miR-146a/b, miR-132/122, and miR-483-3p. Identification of specific microRNAs and their targets and elucidating microRNA-regulated mechanisms associated RAS-mediated cardiovascular inflammation and remodeling might lead to the development of novel pharmacological strategies to target RAAS-mediated vascular pathologies. This paper reviews microRNAs role in inflammatory factors mediating cardiovascular inflammation and RAAS genes and the effect of RAAS pharmacological inhibition on microRNAs and the resolution of RAAS-mediated cardiovascular inflammation and remodeling. Also, this paper discusses the advances on microRNAs-based therapeutic approaches that may be important in targeting RAAS signaling.

Resistance training regulates cardiac function through modulation of miRNA-214

AIMS

To determine the effects of resistance training (RT) on the expression of microRNA (miRNA)-214 and its target in sarcoplasmic reticulum Ca2+-ATPase (SERCA2a), and on the morphological and mechanical properties of isolated left ventricular myocytes.

MAIN METHODS

Male Wistar rats were divided into two groups (n = 7/group): Control (CO) or trained (TR). The exercise-training protocol consisted of: 4 × 12 bouts, 5×/week during 8 weeks, with 80% of one repetition maximum.

KEY FINDINGS

RT increased the left ventricular myocyte width by 15% and volume by 12%, compared with control animals (p < 0.05). The time to half relaxation and time to peak were 8.4% and 4.4% lower, respectively, in cells from TR group as compared to CO group (p < 0.05). RT decreased miRNA-214 level by 18.5% while its target SERCA2a expression were 18.5% higher (p < 0.05).

SIGNIFICANCE

Our findings showed that RT increases single left ventricular myocyte dimensions and also leads to faster cell contraction and relaxation. These mechanical adaptations may be related to the augmented expression of SERCA2a which, in turn, may be associated with the epigenetic modification of decreased miRNA-214 expression.