Exercise training can prevent cardiac hypertrophy induced by sympathetic hyperactivity with modulation of kallikrein-kinin pathway and angiogenesis

Antihypertrophic effects of the seed ethanolic extract of Aframomum pruinosum Gagnep. (Zingiberaceae) against isoproterenol-induced cardiac hypertrophy in male Wistar rat

The seeds of Aframomum pruinosum are popularly used in the management of cardiovascular conditions. This study was undertaken to evaluate the capacity of the seed ethanolic extract of A. pruinosum (EE) to prevent the development of cardiac hypertrophy in rats. Isoproterenol (0.3 mg/kg/day, sc) was injected to male rats alone or concomitantly with EE (37.5, 75, or 150 mg/kg, per os) or propranolol (20 mg/kg/day, per os) for 7 consecutive days and systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate measurements were performed. Cardiac homogenates were used to assay myeloperoxidase (MPO), superoxide dismutase (SOD), catalase, nitric oxide (NO) and reduced glutathione (GSH). Also, sections of heart tissue were stained with Hematoxylin-Eosin, Masson trichrome, or for immunohistological labelling of atrial natriuretic peptide (ANP). Isoproterenol administration caused a decline in SBP and DBP (p < 0.001). Heart rate, cardiac mass, cardiomyocyte surface, and MPO levels were significantly (p < 0.001) increased. All these alterations were significantly prevented (p < 0.01 and p < 0.001) by EE. EE inhibited immune cell infiltration and cardiac fibrosis elicited by isoproterenol injection. The overexpression of ANP in the atrium and ventricle induced by the isoproterenol was significantly (p < 0.001) prevented by EE. EE possesses antihypertrophic effect against isoproterenol-induced cardiac hypertrophy that may result from its antifibrotic, anti-inflammatory properties, as well as its capacity to down regulate the expression of ANP.

How long does the biological effect of a red light-emitting diode last on adipose-derived mesenchymal stem cells?

This research investigated the duration of the influence of red light-emitting diodes (LED, 630 nm; output power: 2452.5 mW; laser beam: 163.5 cm2; irradiance: 15 mW/cm2; radiant exposure: 4 J/cm2) on different periods after irradiation (6, 12, 24, 48, and 72 h) on adipose-derived mesenchymal stem cells' (AdMSCs) metabolism and paracrine factors. AdMSCs were irradiated three times every 48 h. Twenty-four hours after the last irradiation, there was a higher MTT absorbance, followed by a decrease after 48 h. The cells' secretome showed increased levels of IL-6 and VEGF after 12 and 24 h, but this was reversed after 48 h. Additionally, LED irradiation resulted in higher levels of nitrite and did not affect oxidative stress markers. LED irradiation had significant effects on AdMSCs after 24 h compared to other groups and its control group.

Anti-apoptotic and anti-fibrotic efficacy of exercise training in hypertensive hearts: A systematic review

Background

This review aims to summarize the antiapoptotic, pro-survival, and antifibrotic effects of exercise training in hypertensive hearts.

Methods

Keyword searches were conducted in PubMed, Web of Science, and Scopus in May 2021. Research published in English on the effects of exercise training on the apoptosis, survival, and fibrosis pathways in hypertension was included. The CAMARADES checklist was used to determine the quality of the studies. Two reviewers independently implemented predesigned protocols for the search and selection of studies, the assessment of study quality, and the evaluation of the strength of evidence.

Results

Eleven studies were included after selection. The duration of the exercise training ranged from 5 to 27 weeks. Nine studies showed that exercise training improved cardiac survival rates by increasing IGF-1, IGF-1 receptor, p-PI3K, Bcl-2, HSP 72, and p-Akt. Furthermore, 10 studies showed that exercise training reduced apoptotic pathways by downregulating Bid, t-Bid, Bad, Bak, Bax, TNF, and FADD. Finally, two studies reported the modification and subsequent improvement of physiological characteristics of fibrosis and decreased MAPK p38 and PTEN levels by exercise training in the left ventricle of the heart.

Conclusions

The findings of the review showed that exercise training could improve cardiac survival rates and attenuate cardiac apoptotic and fibrotic pathways in hypertension, suggesting that exercise training could act as a therapeutic approach to prevent hypertension-induced cardiac apoptosis and fibrosis.

Systematic Review Registration

https://www.crd.york.ac.uk, identifier: CRD42021254118.

Interrelation among exercise training, cardiac hypertrophy, and tissue kallikrein-kinin system in athlete and non-athlete women

Introduction: The tissue kallikrein-kinin system is an endogenous homeostatic pathway, which its stimulation is associated with cardioprotection. The present study aimed to determine the effect of exercise training on plasma tissue kallikrein (TK) and bradykinin (BK) and their association with cardiac hypertrophy. Methods: 22 non-athlete and 22 athlete women were exposed to acute (Bruce test) and chronic (12-week swimming training) exercises. 2D echocardiography was used to evaluate morphological and functional features of the heart. Plasma concentrations of TK and BK were quantified by ELISA. Results: Athletes had significantly higher values of left ventricle end-diastolic diameter index (LVEDDI) and left ventricle mass index (LVMI) than non-athletes. Exercise intervention affected echocardiographic features in neither of the study groups. Chronic exercise training notably increased plasma levels of TK and BK, which increase was more pronounced in the athletes. Plasma TK negatively correlated with LVEDDI (r=−0.64, P=0.036 and r=−0.58, P=0.027) and LVMI (r=−0.51, P=0.032 and r=−0.63, P=0.028) in the non-athlete and athlete groups. In opposition, there was a positive correlation between plasma TK and left ventricle ejection fraction in non-athletes (r=0.39, P=0.049) and athletes (r=0.53, P=0.019). Conclusion: The upregulation of the tissue kallikrein-kinin system may be a protective mechanism against excessive cardiac hypertrophy induced by chronic exercise training.

Exercise training maintains cardiovascular health: signaling pathways involved and potential therapeutics

Exercise training has been widely recognized as a healthy lifestyle as well as an effective non-drug therapeutic strategy for cardiovascular diseases (CVD). Functional and mechanistic studies that employ animal exercise models as well as observational and interventional cohort studies with human participants, have contributed considerably in delineating the essential signaling pathways by which exercise promotes cardiovascular fitness and health. First, this review summarizes the beneficial impact of exercise on multiple aspects of cardiovascular health. We then discuss in detail the signaling pathways mediating exercise's benefits for cardiovascular health. The exercise-regulated signaling cascades have been shown to confer myocardial protection and drive systemic adaptations. The signaling molecules that are necessary for exercise-induced physiological cardiac hypertrophy have the potential to attenuate myocardial injury and reverse cardiac remodeling. Exercise-regulated noncoding RNAs and their associated signaling pathways are also discussed in detail for their roles and mechanisms in exercise-induced cardioprotective effects. Moreover, we address the exercise-mediated signaling pathways and molecules that can serve as potential therapeutic targets ranging from pharmacological approaches to gene therapies in CVD. We also discuss multiple factors that influence exercise's effect and highlight the importance and need for further investigations regarding the exercise-regulated molecules as therapeutic targets and biomarkers for CVD as well as the cross talk between the heart and other tissues or organs during exercise. We conclude that a deep understanding of the signaling pathways involved in exercise's benefits for cardiovascular health will undoubtedly contribute to the identification and development of novel therapeutic targets and strategies for CVD.

A common oral pathogen Porphyromonas gingivalis induces myocarditis in rats

AIM

To evaluate whether Porphyromonas gingivalis (P. gingivalis) inoculation could induce cardiac remodelling in rats.

MATERIALS AND METHODS

The study was conducted on 33 Wistar rats, which were distributed in the following experimental groups: not inoculated; inoculated with 1 × 10⁸ CFU/ml of bacteria; inoculated with 3 × 10⁸ CFU/ml of bacteria. The animals were inoculated at baseline and on the 15th day of follow-up. Blood collection was performed at baseline and 60 min after each inoculation. At 29 days, the animals were subjected to echocardiography and at 30 days to haemodynamic studies before sacrificing them.

RESULTS

Impact of the bacteria was more evident in rats that received higher P. gingivalis concentration. Thus, 3 × 10⁸ CFU/ml of bacteria increased the rectal temperature and water content in the lung as well as myocardial necrosis and fibrosis. P. gingivalis induced the intensification of DNA fragmentation and increased the levels of malondialdehyde, oxidized proteins, and macrophage expression in the myocardium. These findings were associated with lower LV isovolumetric relaxation time, +dP/dt, -dP/dt, and higher end-diastolic pressure.

CONCLUSIONS

P. gingivalis bacteraemia is significantly associated with adverse cardiac remodelling and may play a biological role in the genesis of heart failure.

Role of Chitinase-3-like Protein 1 in Cardioprotection and Angiogenesis by Post-Infarction Exercise Training

Chitinase-3-like protein 1 (CHI3L1) is a myokine involving tissue remodeling and inflammatory processes. CHI3L1 and its receptor protease-activated receptor 2 (PAR2) are induced by exercise in skeletal muscles. However, it remains unknown if CHI3L1/PAR2 signaling also mediates exercise-induced cardioprotection after myocardial infarction. Twenty-four adult male rats were divided into three groups (n = 8/group), receiving: (1) a sham operation; (2) permanent ligation of left anterior descending coronary artery; and (3) post-MI exercise training with one-week adaptive treadmill exercise for seven days followed by four weeks of aerobic exercise. Left ventricular systolic and end-diastolic pressure indices were measured and cardiac fibrosis, and angiogenesis were examined. Furthermore, HUVEC cells were treated in vitro with AMPK agonist—AICAR (a putative pharmacological memetic of exercise), recombinant human CHI3L1, PAR2 receptor blocker (AZ3451), and PI3K inhibitor (LY294002), respectively. We found that post-MI exercise significantly upregulated CHI3L1, PAR2, pPI3K/PI3K, pAKT/AKT, pERK/ERK, improved cardiac function, and diminished fibrosis. AICAR increased HUVEC tubules formation and upregulated CHI3L1 and PAR2 and these changes were attenuated by PAR2 blocker. In conclusion, post-MI exercise training can effectively activate CHI3L1/PAR2 signaling, which led to the improved myocardial function and enhanced cardiac angiogenesis in the infarcted heart.

Potential Role of Exercise in Regulating YAP and TAZ During Cardiomyocytes Aging

Adaptation of cardiac muscle to regular exercise results in morphological and structural changes known as physiological cardiac hypertrophy, to which the Hippo signaling pathway might have contributed. Two major terminal effectors in the Hippo signaling pathway are Yes-associated protein (YAP) and its homolog transcriptional coactivator with PDZ-binding motif (TAZ). The latest studies have reported the role of YAP and TAZ in different life stages, such as in fetal, neonatal, and adult hearts. Their regulation might involve several mechanisms and effectors. One of the possible coregulators is exercise. Exercise plays a role in cardiomyocyte hypertrophic changes during different stages of life, including in aged hearts. YAP/TAZ signaling pathway has a role in physiological cardiac hypertrophy induced by exercise and is associated with cardiac remodelling. Thus, it can be believed that exercise has roles in activating the signaling pathway of YAP and TAZ in aged cardiomyocytes. However, the studies regarding the roles of YAP and TAZ during cardiomyocyte aging are limited. The primary purpose of this review is to explore the response of cardiovascular aging to exercise via signaling pathway of YAP and TAZ.

Photobiomodulation Therapy on Myocardial Infarction in Rats: Transcriptional and Posttranscriptional Implications to Cardiac Remodeling

BACKGROUND AND OBJECTIVES

Induction of myocardial infarction (MI) in rats by occlusion of the left anterior descending coronary artery is an experimental model used in research to elucidate functional, structural, and molecular modifications associated with ischemic heart disease. Photobiomodulation therapy (PBMT) has become a therapeutic alternative by modulating various biological processes eliciting several effects, including anti-inflammatory and pro-proliferative actions. The main objective of this work was to evaluate the effect of PBMT in the modulation of transcriptional and post-transcriptional changes that occurred in myocardium signal transduction pathways after MI.

STUDY DESIGN/MATERIALS AND METHODS

Continuous wave (CW) non-thermal laser parameters were: 660 nm wavelength, power 15 mW, with a total energy of 0.9 J, fluence of 1.15 J/cm² , spot size of 0.785 cm² , and time of 60 seconds. Using in silico analysis, we selected and then, quantified the expression of messenger RNA (mRNA) of 47 genes of 9 signaling pathways associated with MI (angiogenesis, cell survival, hypertrophy, oxidative stress, apoptosis, extracellular matrix, calcium kinetics, cell metabolism, and inflammation). Messenger RNA expression quantification was performed in myocardial samples by polymerase chain reaction real-time array using TaqMan customized plates.

RESULTS

Our results evidenced that MI modified mRNA expression of several well-known biomarkers related to detrimental cardiac activity in almost all signaling pathways analyzed. However, PBMT reverted most of these transcriptional changes. More expressively, PBMT provoked a robust decrease in mRNA expression of molecules that participate in post-MI inflammation and ECM composition, such as IL-6, TNF receptor, TGFb1, and collagen I and III. Global microRNA (miRNA) expression analysis revealed that PBMT decreased miR-221, miR-34c, and miR-93 expressions post-MI, which are related to deleterious effects in cardiac remodeling.

CONCLUSION

Thus, the identification of transcriptional and post-transcriptional changes induced by PBMT may be used to interfere in the molecular dynamics of cardiac remodeling post-MI.

Aerobic Training-induced Upregulation of YAP1 and Prevention of Cardiac Pathological Hypertrophy in Male Rats

Background

Pathological hypertrophy is one of the negative consequences of cardiac sympathetic hyperactivity. Recent studies have shown that YAP1 plays a critical role in cardiomyocytes hypertrophy. Considering the preventive role of exercise training in cardiovascular diseases, the present study was conducted to examine the effect of aerobic exercise training on YAP1 gene expression and its upstream components.

Methods

Eighteen male Wistar rats were randomly divided into aerobic training and control groups. Aerobic training was performed one hour/day, five days per week, for eight weeks, on a treadmill at 65-75% VO₂ max. Pathological hypertrophy was induced by injecting 3 mg/kg^-1 of isoproterenol for seven days. The left ventricle was separated, and YAP1, 3-mercaptopyruvate sulfurtransferase (MST), large tumor suppressor (LATS), and mitogen-activated protein 4 kinase (MAP4K) gene expressions were assessed and YAP1 protein levels were also assessed by western blotting. Cell apoptosis was detected by TUNEL assays. The between-group differences were evaluated using the T-test and P value <0.05 was considered statistically significant.

Results

There were no significant between-group differences in MST gene expression (P = 0.061); meanwhile, in the training group, LATS and Map4K expressions were suppressed, followed by a significant increase in YAP1 expression (P < 0.001). Compared to the control group, the left ventricular weight increased significantly in the training group while the cardiomyocyte apoptosis decreased.

Conclusions

The results showed that, by reducing LATS, aerobic training-induced YAP1 upregulation can help prevent the propagation of cardiomyocyte apoptosis due to pathological conditions.

Role of Exercise on Alleviating Pressure Overload-Induced Left Ventricular Dysfunction and Remodeling via AMPK-Dependent Autophagy Activation

Cardiac hypertrophy is one of the significant risk factors that result in maladaptive cardiac remodeling and heart failure, and exercise is known to exert cardioprotection. In this research, the cardioprotective function and exercise mechanisms were explored.The rats underwent transverse aortic constriction (TAC) or a sham operation. The rats that received TAC were randomly assigned to five groups: (1) rats subjected to a sham operation as control group (SC), (2) rats that underwent TAC group (TC), (3) TAC and moderate-intensity exercise group (TE), (4) TE plus 3-MA group (TEM), and (5) TE plus Compound C group (TEC). The heart function was measured via echocardiography. Histological analysis and relative protein testing were conducted to analyze collagen deposition and apoptosis. Furthermore, western blot was employed to measure the protein expression of relevant signaling pathways. Impaired cardiac function, interstitial fibrosis, enhanced apoptosis, and ER stress were observed in the TAC-induced left ventricular hypertrophy. Exercise attenuated TAC-induced cardiac dysfunction, interstitial fibrosis, and ER stress-related apoptosis. In addition, exercise significantly improved autophagy and upregulated AMPK phosphorylation. Furthermore, AMPK inhibitor Compound C repressed the activation of AMPK, and autophagy inhibitor 3-methyladenine reversed exercise-induced autophagy. All of these abolished the protection of exercise against cardiac dysfunction and fibrosis induced by TAC.Our results indicated that 4 weeks of treadmill exercise could alleviate pressure overload-induced LV dysfunction and remodeling via an autophagy-dependent mechanism, which was induced by enhancing autophagy through the activation of AMPK.

Human tissue kallikrein-1 protects against the development of erectile dysfunction in a rat model of hyperhomocysteinemia

The aim of this study was to investigate the mechanism by which a diet inducing high hyperhomocysteinemia (HHcy) leads to the deterioration of erectile function in rats and whether this is inhibited by expression of the human tissue kallikrein-1 (hKLK1) gene. We established a rat model of HHcy by feeding methionine (Met)-rich diets to male Sprague-Dawley (SD) rats. Male wild-type SD rats (WTRs) and transgenic rats harboring the hKLK1 gene (TGRs) were fed a normal diet until 10 weeks of age. Then, 30 WTRs were randomly divided into three groups as follows: the control (n = 10) group, the low-dose (4% Met, n = 10) group, and the high-dose (7% Met, n = 10) group. Another 10 age-matched TGRs were fed the high-dose diet and designated as the TGR+7% Met group. After 30 days, in all four groups, erectile function was measured and penile tissues were harvested to determine oxidative stress, endothelial cell content, and penis fibrosis. Compared with the 7% Met group, the TGR+7% Met group showed diminished HHcy-induced erectile dysfunction (ED), indicating the improvement caused by hKLK1. Regarding corpus cavernosum endothelial cells, hKLK1 preserved endothelial cell-cell junctions and endothelial cell content, and activated protein kinase B/endothelial nitric oxide synthase (Akt/eNOS) signaling. Fibrosis assessment indicated that hKLK1 preserved normal penis structure by inhibiting apoptosis in the corpus cavernosum smooth muscle cells. Taken together, these findings showed that oxidative stress, impaired corpus cavernosum endothelial cells, and severe penis fibrosis were involved in the induction of ED by HHcy in rats, whereas hKLK1 preserved erectile function by inhibiting these pathophysiological changes.

Angiogenesis: focusing on the effects of exercise in aging and cancer

[Purpose]

Although it is known that exercise induces angiogenesis, a clear mechanism has remained elusive due to various experimental limitations. This review presents the current status of angiogenesis-related experiments and future directions of experimentation in relation to exercise, aging, and cancer.

[Methods]

We conducted a PubMed search of the available literature to identify reported exercise related changes of angiogenic factors obtained in vitro using C2C12 cells and endothelial cells, and in vivo using animal experiments and in clinical studies.

[Results]

Exercise induced angiogenesis under normal conditions. Aging decreased angiogenic factors and increased during exercise. On the other hand, in cancer, the results indicate that angiogenic factors tend to increase in general, and that the effects of exercise need to be studied more. The exact mechanism remains unclear.

[Conclusion]

The effect of exercise on angiogenesis appears positive. Both resistance and aerobic exercise have positive effects, but many evidences suggest that the effects are more pronounced with aerobic exercise. Further research on the precise mechanism(s) is necessary. It is expected that these studies will include models of aging and cancer.

Swimming Training Improves Myocardial Mechanics, Prevents Fibrosis, and Alters Expression of Ca2+ Handling Proteins in Older Rats

Exercise training effects on the contractility of aged myocardium have been investigated for more than 20 years, but the data are still unclear. This study evaluated the hypothesis that a swimming training (ST) may improve myocardial inotropism in older rats. Male Wistar rats aged 4 (young)-and 21 (old)-months-old were divided into young untrained (YNT), old untrained (ONT), and old trained (OTR; 6 weeks of ST) groups. Echocardiography and hemodynamic were employed to assess left ventricular morphology and function. Myocardial mechanics was evaluated on papillary muscles. Histological and immunoblotting were carried out to evaluate fibrosis and proteins that modulate the myocardial function and calcium handling. We found that older rats did not show cardiac dysfunction, but ONT group showed lower physical performance during a swimming test (YNT: 5 ± 2; ONT: -16 ± 0.4; OTR: 51 ± 3; Δ%, sec). Moreover, ONT group showed worse myocardial inotropism, in which it was reversed by ST (Peak developed tension: YNT: 6.2 ± 0.7; ONT: 3.9 ± 0.3; OTR: 6.9 ± 0.9; g/mm2). The ST was associated with preserved collagen content (YNT: 0.38 ± 0.05; ONT: 0.78 ± 0.12; OTR: 0.34 ± 0.09; %). Exercise partially mitigated the effects of aging on intracellular Ca2+-regulating protein (eg, L-Ca2+ channel and phospholamban) and β-isoform of myosin. Thus, we propose that these molecular alterations together with inhibition of collagen increase contribute to improved myocardial performance in older rats.

Employing Extracellular Volume Cardiovascular Magnetic Resonance Measures of Myocardial Fibrosis to Foster Novel Therapeutics

Quantifying myocardial fibrosis (MF) with myocardial extracellular volume measures acquired during cardiovascular magnetic resonance promises to transform clinical care by advancing pathophysiologic understanding and fostering novel therapeutics. Extracellular volume quantifies MF by measuring the extracellular compartment depicted by the myocardial uptake of contrast relative to plasma. MF is a key domain of dysfunctional but viable myocardium among others (eg, microvascular dysfunction and cardiomyocyte/mitochondrial dysfunction). Although anatomically distinct, these domains may functionally interact. MF represents pathological remodeling in the heart associated with cardiac dysfunction and adverse outcomes likely mediated by interactions with the microvasculature and the cardiomyocyte. Reversal of MF improves key measures of cardiac dysfunction, so reversal of MF represents a likely mechanism for improved outcomes. Instead of characterizing the myocardium as homogenous tissue and using important yet still generic descriptors, such as thickness (hypertrophy) and function (diastolic or systolic), which lack mechanistic specificity, paradigms of cardiac disease have evolved to conceptualize myocardial disease and patient vulnerability based on the extent of disease involving its various compartments. Specifying myocardial compartmental involvement may then implicate cellular/molecular disease pathways for treatment and targeted pharmaceutical development and above all highlight the role of the cardiac-specific pathology in heart failure among myriad other changes in the heart and beyond. The cardiology community now requires phase 2 and 3 clinical trials to examine strategies for the regression/prevention of MF and eventually biomarkers to identify MF without reliance on cardiovascular magnetic resonance. It seems likely that efficacious antifibrotic therapy will improve outcomes, but definitive data are needed.

Preserved Erectile Function in the Aged Transgenic Rat Harboring Human Tissue Kallikrein 1

INTRODUCTION

Human tissue kallikrein 1 (hKLK1) has enormous potential for the protection of vasodilation and endothelial function in the cardiovascular system. Our previous study proved the decreased expression of kallikrein 1 in the corpus cavernosum (CC) of aged rats, but the role of kallikrein 1 in age-related erectile dysfunction remains unknown.

AIM

To explore the effect and underlying mechanisms of hKLK1 on age-related erectile dysfunction.

METHODS

Male wild-type Sprague-Dawley rats (WTR) and transgenic rats harboring the hKLK1 gene (TGR) were fed to 4 and 27 months of age, respectively, and divided into four groups: young WTR (yWTR) as the control, young TGR (yTGR), aged WTR (aWTR), and aged TGR (aTGR). Rats' erectile function was evaluated by the cavernous nerve electrostimulation method. Then, CCs were collected for verification of hKLK1 followed by measurement of nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) and RhoA-Rho-kinase (ROCK) signaling activities. Masson trichrome staining and terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end labeling assay were conducted to evaluate penile fibrosis and apoptosis.

MAIN OUTCOME MEASURES

Erectile response, NO-cGMP and RhoA-ROCK pathway-related indices, ratio of smooth muscle to collagen, and apoptosis index.

RESULTS

The hKLK1 alleviated the decrease of erectile function in the aWTR group. Endothelial NO synthase (eNOS) and phospho-eNOS(Ser1177) expressions, NO synthase activity, and NO and cGMP levels were decreased, whereas phospho-eNOS(Thr495), L-type Ca(2+) channel, RhoA, ROCK1, ROCK2, and transforming growth factor β1 proteins were increased in the CCs of the aWTR group compared with the control yWTR group. These changes were obviously mitigated in the aTGR group. Moreover, hKLK1 prevented the sharp decrease of the ratio of smooth muscle to collagen and the increase of the apoptosis index in the CCs of the aWTR group.

CONCLUSION

These results suggest that hKLK1 could play a preventive role in age-related erectile dysfunction by activation of the NO-cGMP pathway and inhibition of the RhoA-ROCK pathway and by antitissue fibrotic and apoptotic effects.

Low-Level Laser Application in the Early Myocardial Infarction Stage Has No Beneficial Role in Heart Failure

Low-level laser therapy (LLLT) has been targeted as a promising approach that can mitigate post-infarction cardiac remodeling. There is some interesting evidence showing that the beneficial role of the LLLT could persist long-term even after the end of the application, but it remains to be systematically evaluated. Therefore, the present study aimed to test the hypothesis that LLLT beneficial effects in the early post-infarction cardiac remodeling could remain in overt heart failure even with the disruption of irradiations. Female Wistar rats were subjected to the coronary occlusion to induce myocardial infarction or Sham operation. A single LLLT application was carried out after 60 s and 3 days post-coronary occlusion, respectively. Echocardiography was performed 3 days and at the end of the experiment (5 weeks) to evaluate cardiac function. After the last echocardiographic examination, LV hemodynamic evaluation was performed at baseline and on sudden afterload increases. Compared with the Sham group, infarcted rats showed increased systolic and diastolic internal diameter as well as a depressed shortening fraction of LV. The only benefit of the LLLT was a higher shortening fraction after 3 days of infarction. However, treated-LLLT rats show a lower shortening fraction in the 5th week of study when compared with Sham and non-irradiated rats. A worsening of cardiac function was confirmed in the hemodynamic analysis as evidenced by the higher LV end-diastolic pressure and lower +dP/dt and −dP/dt with five weeks of study. Cardiac functional reserve was also impaired by infarction as evidenced by an attenuated response of stroke work index and cardiac output to a sudden afterload stress, without LLLT repercussions. No significant differences were found in the myocardial expression of Akt₁/VEGF pathway. Collectively, these findings illustrate that LLLT improves LV systolic function in the early post-infarction cardiac remodeling. However, this beneficial effect may be dependent on the maintenance of phototherapy. Long-term studies with LLLT application are needed to establish whether these effects ultimately translate into improved cardiac remodeling.

Quantitative Biology of Exercise-Induced Signal Transduction Pathways

Exercise is essential in regulating energy metabolism. Exercise activates cellular, molecular, and biochemical pathways with regulatory roles in training response adaptation. Among them, endurance/strength training of an individual has been shown to activate its respective signal transduction pathways in skeletal muscle. This was further studied from the viewpoint of quantitative difference (QD). For the mean values, [Formula: see text], of two sets of data, their QD is defined as [Formula: see text] ([Formula: see text]). The function-specific homeostasis (FSH) of a function of a biosystem is a negative-feedback response of the biosystem to maintain the function-specific conditions inside the biosystem so that the function is perfectly performed. A function in/far from its FSH is called a normal/dysfunctional function. A cellular normal function can resist the activation of other signal transduction pathways so that there are normal function-specific signal transduction pathways which full activation maintains the normal function.

RESULTS

An acute endurance/strength training may be dysfunctional, but its regular training may be normal. The normal endurance/strength training of an individual may resist the activation of other signal transduction pathways in skeletal muscle so that there may be normal endurance/strength training-specific signal transduction pathways (NEPs/NSPs) in skeletal muscle. The endurance/strength training may activate NSPs/NEPs, but the QD from the control is smaller than 0.80. The simultaneous activation of both NSPs and NEPs may enhance their respective activation, and the QD from the control is larger than 0.80. The low level laser irradiation pretreatment of rats may promote the activation of NSPs in endurance training skeletal muscle.

CONCLUSION

There may be NEPs/NSPs in skeletal muscle trained by normal endurance/strength training.

Association of Exercise Training with Tobacco Smoking Prevents Fibrosis but has Adverse Impact on Myocardial Mechanics

INTRODUCTION

There was no data for cardiac repercussion of exercise training associated with tobacco smoking. This issue is interesting because some smoking people can be enrolled in an exercise-training program. Thus, we evaluated swimming training effects on the function and structural myocardial in rats exposed to tobacco smoking.

METHODS

Male Wistar rats were assigned to one of four groups: C, untrained rats without exposure to tobacco smoking; E, exercised rats without exposure to tobacco smoking; CS, untrained rats exposed to tobacco smoking; ECS, exercised rats exposed to tobacco smoking. Rats swam five times a week twice daily (60min per session) for 8 weeks. Before each bout exercise, rats breathed smoke from 20 cigarettes for 60min. Twenty-four hours after the last day of the protocol, papillary muscles were isolated for in vitro analysis of myocardial mechanics. The myocardial mass and nuclear cardiomyocyte volume were used as hypertrophy markers, and collagen content was determined by picrosirius red staining.

RESULTS

There was a well-pronounced myocardial hypertrophic effect for two interventions. The exercise blunted myocardial collagen increases induced by tobacco smoking. However, exercise and tobacco-smoking association was deleterious to myocardial performance. Thereby, in vitro experiments with papillary muscles contracting in isometric showed impairment myocardial inotropism in exercised rats exposed to tobacco smoking.

CONCLUSIONS

This work presents novel findings on the role of exercise training on cardiac remodeling induced by tobacco smoking. Although exercise has mitigated tissue fibrosis, their association with tobacco smoking exacerbated hypertrophy and in vitro myocardial dysfunction.

IMPLICATIONS

This is first study to show that the association of an aerobic exercise training with tobacco smoking intensifies the phenotype of pathological cardiac hypertrophy. Therefore, the combination of interventions resulted in exacerbated myocardial hypertrophy and contractility dysfunction. These findings have significant clinical implication because some smoking people can be enrolled in an exercise-training program.

Comparative mRNA and MicroRNA Profiling during Acute Myocardial Infarction Induced by Coronary Occlusion and Ablation Radio-Frequency Currents

The ligation of the left anterior descending coronary artery is the most commonly used experimental model to induce myocardial infarction (MI) in rodents. A high mortality in the acute phase and the heterogeneity of the size of the MI obtained are drawbacks recognized in this model. In an attempt to solve the problem, our group recently developed a new MI experimental model which is based on application of myocardial ablation radio-frequency currents (AB-RF) that yielded MI with homogeneous sizes and significantly reduce acute mortality. In addition, cardiac structural, and functional changes aroused by AB-RF were similar to those seen in animals with MI induced by coronary artery ligation. Herein, we compared mRNA expression of genes that govern post-MI milieu in occlusion and ablation models. We analyzed 48 mRNAs expressions of nine different signal transduction pathways (cell survival and metabolism signs, matrix extracellular, cell cycle, oxidative stress, apoptosis, calcium signaling, hypertrophy markers, angiogenesis, and inflammation) in rat left ventricle 1 week after MI generated by both coronary occlusion and AB-RF. Furthermore, high-throughput miRNA analysis was also assessed in both MI procedures. Interestingly, mRNA expression levels and miRNA expressions showed strong similarities between both models after MI, with few specificities in each model, activating similar signal transduction pathways. To our knowledge, this is the first comparison of genomic alterations of mRNA and miRNA contents after two different MI procedures and identifies key signaling regulators modulating the pathophysiology of these two models that might culminate in heart failure. Furthermore, these analyses may contribute with the current knowledge concerning transcriptional and post-transcriptional changes of AB-RF protocol, arising as an alternative and effective MI method that reproduces most changes seem in coronary occlusion.

A Pilot Study to Assess Adenosine 5'-triphosphate Metabolism in Red Blood Cells as a Drug Target for Potential Cardiovascular Protection

OBJECTIVE

To study the effect of exercise preconditioning on adenosine 5'triphosphate (ATP) metabolism in red blood cells and cardiovascular protection against injury induced by isoproterenol in vivo.

METHODS

Male Sprague Dawley rats (SDR) were each exercised on a treadmill for 15 minutes at 10 m/min and 10% grade (n = 7) (LowEx), or 14 m/min and 22% grade (n = 8) (VigEx). Two hours after the exercise, each rat received a single dose of isoproterenol (30 mg/kg) by subcutaneous (sc) injection. Two separate groups of SDR were used as control: One received no exercise (n = 10) (NoEx) and the other received no exercise and no isoproterenol (n = 11) (NoIso). Serial blood samples were collected over 5 hours for measurement of ATP and its catabolites by a validated HPLC. Hemodynamic recording was collected continuously for the duration of the experiment. Data were analysed using ANOVA and t-tests and difference considered significant at p < 0.05.

RESULTS

Exercise pre-conditioning (both LowEx and VigEx) reduced mortality after isoproterenol from 50% to < 30% (p > 0.05). It attenuated the rebound in blood pressure significantly (p < 0.05 between NoEx vs VigEx), attenuated the increase of RBC adenosine 5'-monophosphate (AMP) concentrations induced by isoproterenol, and also decreased the breakdown of ATP to AMP in the RBC (p < 0.05 vs NoEx).

CONCLUSION

Exercise pre-conditioning decreased the blood pressure rebound and also breakdown of ATP in RBC after isoproterenol which may be exploited further as a drug target for cardiovascular protection and prevention.

Exercise training improves insulin release during glucose tolerance testing in stable chronic heart failure patients

PURPOSE

Chronic heart failure (CHF) patients often present with (pre)diabetes, which negatively influences prognosis. Unlike the proven effect of exercise on glucose regulation in the general population, its effect in CHF is unclear. Therefore, this study aimed at investigating the effect of exercise training on glucose regulation in stable CHF patients.

METHODS

Twenty-two CHF patients were randomized into training (EX, n = 15) and control (CON, n = 7) groups. Before and after a 12-week training intervention involving endurance and resistance training, glucose tolerance (2-hour oral glucose tolerance test), exercise tolerance (cardiopulmonary exercise test), muscle strength (isokinetic dynamometer), heart function (echocardiography), glycated hemoglobin, body composition (dual-energy x-ray absorptiometry), and quality of life (EQ5D) were assessed.

RESULTS

At baseline, glucose levels 2 hours after glucose intake were elevated in both groups. Whereas area under the glucose curve did not change, area under the insulin curve decreased following training (EX, -13 ± 23% vs CON, +22 ± 33%; P < .05). Changes in the ratio of mitral peak velocity of early filling/early diastolic mitral annular velocity and waist-to-hip fat mass ratio were related to changes in the insulin curve. Exercise training resulted in improved oxygen uptake at the second ventilatory threshold (EX, +10 ± 5% vs CON, -8 ± 5%; P < .05) and isokinetic strength endurance of the upper leg (EX, +25 ± 9% vs CON, -6 ± 5%; P < 0.05). Lean body tissue was increased by 2.2 ± 0.5% in EX versus 0.2 ± 0.6% in CON (P < .05).

CONCLUSION

Our data suggest that exercise training attenuates worsening of glucose regulation typically seen in a stable CHF population.