Sedentary Myocardial Infarction Research Articles

Resistance exercise alleviates the prefrontal lobe injury and dysfunction by activating SESN2/AMPK/PGC-1α signaling pathway and inhibiting oxidative stress and inflammation in mice with myocardial infarction

ObjectivesMyocardial infarction (MI) induces inflammatory response and oxidative stress in the brain, which would be one of the causes of cardiac dysfunction. Exercise training is viewed as a feasible strategy to improve cardiac function of the infarcted heart. The aim of this study was to investigate whether exercise training could alleviate MI-induced prefrontal lobe injury via activating Sestrin2 (SESN2) signaling and inhibiting oxidative stress and inflammation. MethodsMale C57BL/6 mice were divided into five groups: control group (CON), aerobic exercise group (AE), resistance exercise group (RE), whole-body vibration group (WBV) and electrical stimulation group (ES); and three groups: sham-operated group (S), sedentary MI group (MI) and MI with resistance exercise group (MRE). After four weeks of training, sensorimotor function, spatial learning, long-term and spatial memory, and cardiac function were detected. Then, mice were euthanized, and the prefrontal areas were separated for HE, Nissl, SESN2, microtubule-associated protein 2 (MAP2), neuron-specific nucleoprotein (NeuN), and TUNEL staining. Activation of SESN2/adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α) signaling pathway and expression of proteins related to oxidative stress, inflammation and apoptosis in the prefrontal lobe were detected by western blotting. ResultsDifferent types of exercise training all activated the SESN2/AMPK/PGC-1α signaling pathway, and the effect of RE is the best. RE improved sensorimotor, learning, and memory impairments, increased the expressions of antioxidant, anti-inflammatory and anti-apoptotic proteins, reduced oxidative stress, inflammation and apoptosis, ultimately alleviated the prefrontal lobe injury and dysfunction in mice with MI. ConclusionRE alleviates MI-indued prefrontal lobe injury and dysfunction by inhibiting the levels of oxidative stress, inflammation and apoptosis, partially via activating SESN2/AMPK/PGC-1α signaling pathway.

Influence of moderate and high intensity interval training on infarcted rat diaphragm

Abstract Background Respiratory muscle dysfunction is commonly observed in heart failure (HF) patients and contributes to early fatigue and dyspnea. As there is no specific pharmacological therapy to treat skeletal muscle changes, physical exercise is considered an important strategy to prevent HF-associated skeletal myopathy. However, which exercise type is better during HF is unsettled. Purpose To evaluate the effects of aerobic and high intensity interval (HIIT) training on diaphragm morphometric, biochemical, and molecular parameters in infarcted rats. Methods Three months after inducing myocardial infarction (MI), male Wistar rats were assigned into three groups: sedentary MI (MI-Sed, n=8), MI subjected to aerobic exercise (MI-A, n=8), and MI subjected to HIIT (MI-HIIT, n=8). Results were compared to a Sham group (n=8). Exercise was performed in treadmill three times a week for three months. Functional capacity test and echocardiogram were performed before and after exercise protocols. Myosin heavy chain (MyHC) isoforms were analyzed by electrophoresis; diaphragm mitogen activated protein kinases (MAPK), NF-κB, TNF-α, and Pax-7 protein expression was evaluated by Western-blot. Statistical analysis: ANOVA. Results Functional capacity was similarly improved by both exercise protocols. Infarction size evaluated by histological analysis did not differ between groups (MI-Sed 27.7±10.8; MI-A 29.6±12.9; MI-HIIT 27.4±12.2% of total left ventricle area; p=0.91). Echocardiographic parameters did not differ between MI groups before and after exercise. Cross sectional area of diaphragm fibers (Sham 1922±230; MI-Sed 1808±264; MI-A 1926±209; MI-HIIT 2007±286 μm2), collagen interstitial fractional area (Sham 4.93±1.76; MI-Sed 5.01±1.88; MI-A 4.55±1.18; MI-HIIT 3.94±1.15%), and percentage of MyHC isoforms did not differ between groups. Pax-7 expression was lower in MI-HIIT than MI-Sed and MI-A [Sham 1.15 (0.58–1.44), MI-Sed 1.19 (0.90–2.85), MI-A 1.46 (0.77–2.14), MI-HIIT 0.46 (0.29–0.66) arbitrary units]. Total p-38 expression was higher in MI-Sed than the other groups and lower in MI-HIIT than Sham [Sham 1.00±0.52; MI-Sed 1.77±0.47; MI-A 0.66±0.22; MI-HIIT 0.46±0.31 arbitrary units]. The other proteins did not differ between groups. Conclusion Both aerobic and high intensity interval training improves functional capacity with no influence on diaphragm of rats with myocardial infarction. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): FAPESP (São Paulo Research Foundation)

Swimming training attenuates the decrease of calcium responsiveness in female infarcted rats.

Aim: To evaluate the influence of swimming training on calcium responsiveness of the myocardium of rats with different infarction sizes (MI). Method: female Wistar rats, sedentary sham (SS = 14), sedentary moderate MI (SMI = 8) and sedentary large MI (SLI = 10) were compared to trained sham (TS = 16), trained moderate MI (TMI = 9) and trained large MI (TLI = 10). After 4 weeks of MI, the animals swam for 60 min/day, 5 days/week, for additional 8 weeks. Papillary muscles of the left ventricle were subjected to different concentrations of extracellular calcium. Inotropism was evaluated through the developed tension (DT), the maximum positive value of the first temporal derivation (+Td/td) and the time to peak tension (TPT). Lusitropism was evaluated by the maximum negative value of the first temporal derivation (−Td/td) and time to 50% relaxation (50%TR). Statistical significance was determined using multivariate analysis of variance and a Hotelling T2 test for the absolute power values of all four extracellular calcium concentrations (p < 0.05). Results: MI depressed inotropism (from 17% to 51%) and lusitropism (from 22% to 54%) of the sedentary rats, but exercise attenuated the losses, especially regarding + dT/dt, TPT, −dT/dt and 50%TR. Exercise attenuated the decrease in myocardial responsiveness, proportionally to the size of the MI. Conclusion: Myocardial calcium responsiveness is favorably affected in animals with moderate and large MI after swimming exercise.

Electrical activity in exercise trained infarcted rat hearts

Myocardial infarction (MI) is a major cause of cardiac arrhythmias. The aim of the study was to determine if exercise training changes the electrical conduction into, within and emerging from an infarcted area of a rat heart. Rats were divided into three groups: sedentary sham, sedentary MI, and exercise training MI. The impact of MI and exercise training on susceptibility to ventricular tachycardias (VTs) was evaluated by in vivo intra-cardiac pacing. Rats with sustained VTs were converted before sacrifice and electrophysiological experiments and optical imaging with voltage-sensitive dye were performed on perfused hearts.

Aerobic exercise and resistance exercise alleviate skeletal muscle atrophy through IGF-1/IGF-1R-PI3K/Akt pathway in mice with myocardial infarction.

Myocardial infarction (MI)-induced heart failure (HF) is commonly accompanied with profound effects on skeletal muscle. With the process of MI-induced HF, perturbations in skeletal muscle contribute to muscle atrophy. Exercise is viewed as a feasible strategy to prevent muscle atrophy. The aims of this study were to investigate whether exercise could alleviate MI-induced skeletal muscle atrophy via insulin-like growth factor 1 (IGF-1) pathway in mice. Male C57/BL6 mice were used to establish the MI model and were divided into three groups: sedentary MI group (MI), MI with aerobic exercise group, and MI with resistance exercise group; sham-operated group was used as control. Exercise-trained animals were subjected to 4 wk of aerobic exercise (AE) or resistance exercise (RE). Cardiac function, muscle weight, myofiber size, levels of IGF-1 signaling and proteins related to myogenesis, protein synthesis, and degradation and apoptosis in gastrocnemius muscle were detected. H2O2-treated C2C12 cells were intervened with recombinant human IGF-1, IGF-1 receptor (IGF-1R) inhibitor NVP-AEW541, and PI3K inhibitor LY294002 to explore the mechanism. Exercises upregulated the IGF-1/IGF-1R-phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling; increased the expressions of Pax7, myogenic regulatory factors (MRFs), and protein synthesis; and reduced protein degradation and cell apoptosis in MI mice. In vitro, IGF-1 upregulated the levels of Pax7, MRFs, mTOR, and P70S6K; reduced MuRF1 and MAFbx; and inhibited cell apoptosis via IGF-1R-PI3K/Akt pathway. AE and RE, safely and effectively, alleviate skeletal muscle atrophy by regulating the levels of myogenesis, protein degradation, and cell apoptosis in mice with MI via activating IGF-1/IGF-1R-PI3K/Akt signaling pathway.

Effects of aerobic interval training on myocardial oxidative stress and inflammation in rats with myocardial infarction and its mechanism

Objective: The present study was to determine the effects of aerobic interval training (AIT) on the expressions of SIRT1, Nox4 and inflammatory factor in the heart of rats with myocardial infarction (MI). Methods: Male Sprague Dawley rats were randomly divided into sham-operated group (C), sedentary MI group (MI) and MI with AIT group (ME) (n=10). The MI model was established by ligation the left anterior descending coronary artery. Rats in C groups were subjected to the same surgery, but only threaded and not ligated. After surgery 1 week, rats in ME groups took adaptability training for 1 week, and then subjected to 4 weeks treadmill exercise training. After training, the hearts were collected for histological observation. The level of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) in heart was assessed by ultraviolet spectrophotometry. The activity of lactate dehydrogenase (LDH) was determined by enzyme linked immunosorbent assay. The expression of sirtuin1 (SIRT1) mRNA was examined by real-time quantitative polymerase chain reaction (RT-qPCR). The protein expressions of SIRT1, NADPH oxidase 4 (Nox4), tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) were detected by Western blotting. The levels of reactive oxygen species (ROS) were detected by dihydroethidium (DHE) staining. Results: Compared with the C group, the expression level of cardiac Nox4 protein was increased (P＜0.01), the level of MDA, activity of LDH and the level of ROS were increased significantly (P＜0.01), and the expressions of TNF-α and IL-1β protein were augmented in the heart of rats with MI (P＜0.01). However, the expressions of SIRT1 mRNA and protein and the activity of SOD were obviously decreased in MI group (P＜0.01). Furthermore, compared with the MI group, AIT increased the expressions of SIRT1 mRNA and protein and the activity of SOD in the heart of ME group (P＜0.01); Meanwhile, the expressions of cardiac Nox4, MDA level, LDH activity and ROS level were diminished in ME group (P＜0.01) as well as the decreased expressions of TNF-α and IL-1β protein (P＜0.01). SIRT1 expression was negatively related to the expressions of NOX4 and ROS. Conclusion: AIT obviously inhibited myocardial oxidative stress and inflammatory reaction, improved cardiac function in rats with MI, and the mechanism was closely related to the activation of SIRT1-Nox4-ROS signaling pathway.

Concurrent vitamin D supplementation and exercise training improve cardiac fibrosis via TGF-β/Smad signaling in myocardial infarction model of rats.

Although the role of vitamin D in various types of disorders such as cancer and diabetes has been well recognized, its relation to cardiovascular diseases still remains equivocal. The present study aims to investigate the interactive effects of aerobic-resistance training (ART) and vitamin D3 (VD3) on both cardiac fibrosis and heart functions considering TGF-β1/Smad2, 3 (transforming growth factor-β1/mothers against decapentaplegic homolog 2/3) signaling in the myocardial infarction (MI) model of rats. Fifty-six male Wistar rats were divided into 2 groups of sham (n = 8), and MI (n = 48). Then, MI rats were divided into six groups of VD3, ART, VD3+ART, Veh, Veh+ART, and sedentary MI. The animals received the related treatments for 8weeks, and then their functional exercise capacity (FEC) and strength gain (SG) were estimated through exercise tests. Ejection fraction (EF%) and fractional shortening (FS%) and serum level of VD3 were measured by echocardiography and ELISA, respectively. Cardiac expressions of TGF-β1, Smad2/3, and collagen I/III were assessed by western blotting and fibrosis by Masson's trichrome staining. The highest EF, parallel with the lowest expression of cardiac TGF-β1, Smad2/3, collagen I, and collagen III were observed in MI + VD3 (P = 0.021), MI + ART (P = 0.001), and MI + VD3 + ART (P < 0.001). Furthermore, similar to FS, the highest FEC and SG were related to the groups of MI + VD3 + ART and MI + ART compared to the MI group. In conclusion, our data indicate that concurrent vitamin D supplementation and ART, compared with monotherapy, successfully improve cardiac function and alleviate myocardial fibrosis via downregulating TGF-β1, Smad2/3 signaling, and also regulating collagen I and III expressions.

Dynamic resistance exercise increases skeletal muscle-derived FSTL1 inducing cardiac angiogenesis via DIP2A–Smad2/3 in rats following myocardial infarction

PurposeThe aim of this study was to investigate the potential of dynamic resistance exercise to generate skeletal muscle-derived follistatin like-1 (FSTL1), which may induce cardioprotection in rats following myocardial infarction (MI) by inducing angiogenesis. MethodsMale, adult Sprague-Dawley rats were randomly divided into 5 groups (n = 12 in each group): sham group (S), sedentary MI group (MI), MI + resistance exercise group (MR), MI + adeno-associated virus (AAV)–FSTL1 injection group (MA), and MI + AAV–FSTL1 injection + resistance exercise group (MAR). The AAV–FSTL1 vector was prepared by molecular biology methods and injected into the anterior tibialis muscle. The MI model was established by ligation of the left anterior descending coronary artery. Rats in the MR and MAR groups underwent 4 weeks of dynamic resistance exercise training using a weighted climbing-up ladder. Heart function was evaluated by hemodynamic measures. Collagen volume fraction of myocardium was observed and analyzed by Masson's staining. Human umbilical vein vessel endothelial cells culture and recombinant human FSTL1 protein or transforming growth factor-β receptor 1 (TGFβR1) inhibitor treatment were used to elucidate the molecular signaling mechanism of FSTL1. Angiogenesis, cell proliferation, and disco interacting protein 2 homolog A (DIP2A) location were observed by immunofluorescence staining. The expression of FSTL1, DIP2A, and the activation of signaling pathways were detected by Western blotting. Angiogenesis of endothelial cells was observed by tubule experiment. One-way analysis of variance and Student's t test were used for statistical analysis. ResultsResistance exercise stimulated the secretion of skeletal muscle FSTL1, which promoted myocardial angiogenesis, inhibited pathological remodeling, and protected cardiac function in MI rats. Exercise facilitated skeletal muscle FSTL1 to play a role in protecting the heart. Exogenous FSTL1 promoted the human umbilical vein vessel endothelial cells proliferation and up-regulated the expression of DIP2A, while TGFβR1 inhibitor intervention down-regulated the phosphorylation level of Smad2/3 and the expression of vascular endothelial growth factor-A, which was not conducive to angiogenesis. FSTL1 bound to the receptor, DIP2A, to regulate angiogenesis mainly through the Smad2/3 signaling pathway. FSTL1–DIP2A directly activated Smad2/3 and was not affected by TGFβR1. ConclusionDynamic resistance exercise stimulates the expression of skeletal muscle-derived FSTL1, which could supplement the insufficiency of cardiac FSTL1 and promote cardiac rehabilitation through the DIP2A–Smad2/3 signaling pathway in MI rats.

Effects of late aerobic exercise on cardiac remodeling of rats with small myocardial infarction

Abstract Background Physical exercise has been highlighted as an important non-pharmacological therapy for prevention and treatment of several cardiovascular diseases. However, its effects on hearts with minor cardiac remodeling are not clear. Purpose To evaluate the influence of aerobic physical exercise on functional capacity, cardiac structure, left ventricular (LV) function, and gene expression of NADPH oxidase subunits in rats with small-sized myocardial infarction (MI). Methods Three months after MI induction, Wistar rats were divided into three groups: Sham; sedentary MI (MI-SED); and aerobic exercised MI (MI-EA). Rats exercised three times a week for 12 weeks on a treadmill. Echocardiogram was performed before and after experimental period. Infarction size and cardiomyocyte diameters were evaluated by histology. Gene expression was assessed by RT-PCR. Results Only rats with MI size lower than 30% of LV total area were included in the study. Functional capacity was higher in MI-AE than the other groups. Infarction size did not differ between groups. Infarcted rats had increased LV diastolic and systolic diameter, left atrial diameter, and LV mass, with systolic dysfunction. LV diastolic posterior wall thickness was higher in MI-AE than Sham, and relative wall thickness was lower in MI-SED than MI-AE and Sham groups. Cardiomyocyte diameter was smaller in infarcted groups than Sham. Myocardial gene expression of the NADPH oxidase subunits NOX2, NOX4, p22phox, and p47phox did not differ between groups. Conclusion Small-sized myocardial infarction changes cardiac structures and left ventricular systolic function. Late aerobic physical exercise improves functional capacity and cardiac remodeling by preserving left ventricular geometry. NADPH oxidase subunits gene expression is not involved in cardiac remodeling or modulated by aerobic exercise in rats with small myocardial infarction. Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): CNPq; CAPES

Aerobic training prevents cardiometabolic changes triggered by myocardial infarction in ovariectomized rats.

This study aimed to evaluate the impact of aerobic training (AT) on autonomic, cardiometabolic, ubiquitin-proteasome activity, and inflammatory changes evoked by myocardial infarction (MI) in ovariectomized rats. Female Wistar rats were ovariectomized and divided into four groups: sedentary + sham (SS), sedentary + MI (SI), AT + sham surgery (TS), AT + MI (TI). AT was performed on a treadmill for 8 weeks before MI. Infarcted rats previously subjected to AT presented improved physical capacity, increased interleukin-10, and decreased pro-inflammatory cytokines. Metabolomic analysis identified and quantified 62 metabolites, 9 were considered significant by the Vip Score. SS, SI, and TS groups presented distinct metabolic profiles; however, TI could not be distinguished from the SS group. MI dramatically increased levels of dimethylamine, and AT prevented this response. Our findings suggest that AT may be useful in preventing the negative changes in functional, inflammatory, and metabolic parameters related to MI in ovariectomized rats.

Voluntary exercise and cardiac remodeling in a myocardial infarction model.

We investigated the effects of voluntary exercise after myocardial infarction (MI) on cardiac function, remodeling, and inflammation. Male C57BL/6J mice were divided into the following four groups: sedentary + sham (Sed-Sh), sedentary + MI (Sed-MI), exercise + sham (Ex-Sh), and exercise + MI (Ex-MI). MI induction was performed by ligation of the left coronary artery. Exercise consisting of voluntary wheel running started after the operation and continued for 4 weeks. The Ex-MI mice had significantly increased cardiac function compared with the Sed-MI mice. The Ex-MI mice showed significantly reduced expression levels of tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-10 in the infarcted area of the left ventricle compared with the Sed-MI mice. In the Ex-MI mice, the expression levels of fibrosis-related genes including collagen I and III were decreased compared to the Sed-MI mice, and the expression levels of IL-1β, IL-6, follistatin-like 1, fibroblast growth factor 21, and mitochondrial function-related genes were significantly elevated in skeletal muscle compared with the Sed mice. The plasma levels of IL-6 were also significantly elevated in the Ex-MI group compared with the Sed-MI groups. These findings suggest that voluntary exercise after MI may improve in cardiac remodeling associated with anti-inflammatory effects in the myocardium and myokine production in the skeletal muscles.

Effects of exercise on BDNF-TrkB signaling in the paraventricular nucleus and rostral ventrolateral medulla in rats post myocardial infarction

Brain-derived neurotrophic factor (BDNF)-tropomyosin-related kinase B (TrkB) signaling in the paraventricular nucleus (PVN) and rostral ventrolateral medulla (RVLM) is associated with cardiovascular regulation. Exercise increases plasma BDNF and attenuates activation of central pathways in the PVN and RVLM post myocardial infarction (MI). The present study assessed whether MI alters BDNF-TrkB signaling and intracellular factors Ca2+/calmodulin-dependent protein kinase II (CaMKII) and Akt in the PVN and RVLM of male Wistar rats with or without exercise or treatment with the TrkB blocker ANA-12. A 4-week period of treadmill exercise training was performed in MI rats. A separate experiment was conducted with 2.5 mg/kg ANA-12 in sedentary MI rats. At 5 weeks post MI, in both the PVN and RVLM, the ratio of full-length TrkB (TrkB.FL) and truncated TrkB (TrkB.T1) was decreased. 0.5 mg/kg ANA-12 did not affect BDNF-TrkB signaling and cardiac function post MI, but 2.5 mg/kg ANA-12 further decreased ejection fraction (EF). Exercise increased mature BDNF (mBDNF) and decreased Akt activity in the PVN, whereas in the RVLM, exercise did not affect mBDNF but lowered p-CaMKIIβ. ANA-12 prevented the exercise-induced increase in mBDNF in the PVN and decrease in p-CaMKIIβ in the RVLM. In conclusion, exercise decreases Akt activity in the PVN and decreases p-CaMKIIβ in the RVLM post MI. BDNF-TrkB signaling only mediates the decrease in p-CaMKIIβ in the RVLM. The exercise-induced decreases in Akt activity in the PVN and p-CaMKIIβ in the RVLM may contribute to the attenuation of the decrease in EF and sympathetic hyperactivity post MI.

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

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

P2499Effects of aerobic and resistance exercise on skeletal muscle of infarcted rats

Abstract Background Skeletal muscle changes contribute to reduced physical performance after myocardial infarction (MI). Exercise has been recommended to stable patients. However, the effects of resistance exercise after MI are not clear. We compared the effects of aerobic and resistance exercise initiated during compensated cardiac remodeling in infarcted rat gastrocnemius muscle. Methods Three months after MI induction, Wistar rats were divided into four groups: Sham (n=20); sedentary MI (MI-S, n=9); aerobic exercised MI (MI-A, n=9); and resistance exercised MI (MI-R, n=13). Exercised rats trained three times a week for 12 weeks on a treadmill or ladder. Energy metabolism, oxidative stress markers, and antioxidant enzyme activities were assessed by spectrophotometry. Satellite cells activation markers (MyoD, NCAM, and myosin heavy chain neonatal isoform) were assessed by immunofluorescence or Western blot (Pax-7). Statistical analysis: ANOVA or Mann Whitney. Results Physical aerobic capacity was greater in MI-A and strength gain higher in MI-R. Cardiac structures and left ventricular function evaluated by echocardiogram did not differ between infarcted groups. Histological analysis showed that MI size and gastrocnemius cross sectional area did not differ between infarcted groups. Oxygen reactive species production was higher in MI-S than Sham and lipid hydroperoxide concentration was lower in MI-A than the other groups. Catalase activity was higher and glutathione peroxidase lower in infarcted groups than Sham. Superoxide dismutase activity was higher in Sham and MI-R than MI-S. Skeletal muscle metabolism enzyme activity did not differ between groups, except for increase pyruvate kinase in MI-S against the other groups, and β-hydroxyacyl CoA dehydrogenase in MI-S against Sham. Satellite cell activation and protein expression of MAPK and NF-kB did not differ between groups. Conclusion Aerobic and resistance exercise respectively improves physical capacity and muscle strength without changing echocardiographic parameters of infarcted rats. Myocardial infarction increases oxygen reactive species production and changes antioxidant enzyme activity and glucose and fatty acid metabolism. Aerobic exercise is superior to resistance exercise against oxidative stress reducing muscle lipid hydroperoxide concentration and attenuating change in glutathione peroxidase activity. Acknowledgement/Funding Financial support: Fapesp, CNPq, Capes, and UNESP

Effects of interval training on calcium transient and contractile function of single ventricular myocyte in myocardial infarction adult rats

To investigate the effects of interval training on calcium transient and contractile function in ischemic ventricular myocytes of rats with myocardial infarction and their synchronization. Twenty-four male sprague-dawley rats in three years old, were randomly divided into three groups (n=8): sham-operated group(S), sedentary MI group(MI) and MI with interval training group (ME). The MI model was established by ligation of the left anterior descending coronary artery. The rats in ME group started training 1 week after MI operation. The S model was established by threading only without ligation. ME model took one week adaptive training, 10 m/min and 30 min/d, then took subsequently 8-week aerobic interval training: 10 min×10 m/min, then reran the rats with 2 intensities 15 m/min×6 min and 25 m/min×4 min, 1 h/d, 5 d/week. After training 24 hours, the cardiomyocytes of all groups were isolated by using the Langendorff fusion system. The contractile function and calcium transient of single ventricular myocyte in myocardial infarction adult rats were detected by IonOptix. Calcium transients were measured as [Ca2+]i amplitude, departure velocity, ratio, TTB50％, TTP and TTP50%, return velocity and ratio amplitude. PTA, SL, ±dl/dtmax and SL shortening% were tested to evaluate contractility. Compared with S, the levels of [Ca2+]i amplitude, departure velocity, ratio amplitude and return velocity, SL shortening%, PTA and ±dl/dtmax of MI were decreased(P＜0.01), the levels of TTP, TTP50% and TTB50% of MI were increased(P＜0.01); Compared with MI, the levels of departure velocity, ratio amplitude, return velocity and [Ca2+]i amplitude of ME were increased(P＜0.01), the levels of TTB50%, TTP and TTP50% of ME were decreased(P＜0.01, P＜0.05). The levels of SL shortening%, PTA and ±dl/dtmax of ME were increased(P＜0.01, P＜0.05). Interval training can improve calcium transient and contractile function of single ventricular myocyte in myocardial infarction adult rats.

Effects of exercise training and TrkB blockade on cardiac function and BDNF-TrkB signaling postmyocardial infarction in rats.

Exercise training is beneficial for preserving cardiac function postmyocardial infarction (post-MI), but the underlying mechanisms are not well understood. We investigated one possible mechanism, brain-derived neurotrophic factor (BDNF)-tropomyosin-related kinase B (TrkB) signaling, with the TrkB blocker ANA-12 (0.5 mg·kg-1·day-1). Male Wistar rats underwent sham surgery or ligation of the left descending coronary artery. The surviving MI rats were allocated as follows: sedentary MI rats treated with vehicle, exercise-trained MI rats treated with vehicle, and exercise-trained MI rats treated with ANA-12. Exercise training was done 5 days/wk for 4 wk on a motor-driven treadmill. At the end, left ventricular (LV) function was evaluated by echocardiography and a Millar catheter. Mature BDNF and downstream effectors of BDNF-TrkB signaling, Ca2+/calmodulin-dependent protein kinase II (CaMKII), Akt, and AMP-activated protein kinase (AMPK), were assessed in the noninfarct area of the LV by Western blot analysis. Exercise training increased stroke volume and cardiac index and attenuated the decrease in ejection fraction (EF) and increase in LV end-diastolic pressure post-MI. ANA-12 blocked the improvement of EF and attenuated the increases in stroke volume and cardiac index but did not affect LV end-diastolic pressure. Exercise training post-MI prevented decreases in mature BDNF, phosphorylated (p-)CaMKII, p-Akt, and p-AMPKα expression. These effects were all blocked by ANA-12 except for p-AMPKα. In conclusion, the exercise-induced improvement of EF is mediated by the BDNF-TrkB axis and the downstream effectors CaMKII and Akt. BDNF-TrkB signaling appears to contribute to the improvement in systolic function by exercise training. NEW & NOTEWORTHY Exercise training improves ejection fraction and left ventricular end-diastolic pressure (LVEDP) and increases stroke volume and cardiac index in rats postmyocardial infarction (post-MI). The improvement of EF but not LVEDP is mediated by activation of the brain-derived neurotrophic factor (BDNF)-tropomyosin-related kinase B (TrkB) axis and downstream effectors Ca2+/calmodulin-dependent protein kinase II (CaMKII) and Akt. This suggests that activation of BDNF-TrkB signaling and CaMKII and Akt is a promising target to attenuate progressive cardiac dysfunction post-MI.

PO-163 Aerobic exercise activates myocardial FGF21/FGFR1/PI3K-AKT signaling pathway and inhibits cardiomyocyte apoptosis in post-myocardial infarction rats

Objective To investigate the effect of aerobic exercise on the expression of fibroblast growth factor 21 (FGF21) and cardiomyocyte apoptosis in Myocardial Infarction (MI) rats.&#x0D; Methods male SD rats were randomly divided into three groups：the sham operation (S), sedentary MI group (MI) and MI with aerobic exercise group (ME). The MI model was established by ligation of the left anterior descending branch of the left coronary artery. ME group were trained four weeks after the operation. LVSP, LVEDP and ±dp/dtmax were used to evaluate cardiac function. H9C2 cardiomyocytes were stimulated by 400 μmol/L H2O2 for 4h to simulate myocardial apoptosis mode. AMPK agonist AICAR and FGF21 receptor inhibitor PD166866 were used to interfere with H9C2. Myocardial collagen volume fraction was calculated by Masson staining and myocardium FGF21, FGFR1, Bax, Bcl-2 and PI3K-AKT pathway by western blotting or RT-Qpcr. Cardiomyocytes apoptosis was evaluated by TUNEL.&#x0D; Results Compared with S, the expression of FGF21, FGFR1, Bax, Bcl-2 and PI3K, AKT increased significantly in MI group, the apoptotic cardiomyocytes and collagen fibers increased significantly, but the cardiac function decreased. Compared to MI, myocardium FGF21, FGFR1 and PI3K, AKT were further increased in ME group, the Bax/Bcl-2 and the apoptotic cardiomyocytes decreased significantly. The percentage of collagen fibers decreased and the cardiac function was improved. Myocardium FGF21 was positively correlated with the inhibition of cardiomyocyte apoptosis and the improvement of cardiac function. Furthermore, the expression of Bax/Bcl-2, TNF-α/IL-10 and the apoptotic cardiomyocytes was significantly increased by PD166866, but PI3K-AKT pathway decreased significantly by PD166866. However, AICAR single intervention or PD166866 simultaneous intervention also can reverse this adverse effects.&#x0D; Conclusions Exercise can increase myocardial FGF21/FGFR1 with MI. The one of the mechanisms is to activate PI3K-AKT pathway to inhibit cardiaomyocyte apoptosis and inflammatory. It indicates that FGF21/FGFR1/PI3K-AKT signaling pathway plays an important role in inhibiting myocardial apoptosis and improving cardiac function.

PO-190 Exercise Training Protects Against Cardiac Pathological Remodeling in Myocardial Infarction rats via Improving Mitochondrial Biogenesis

Objective Growing evidence suggests that exercise training reverses cardiac pathological remodeling and cardiac dysfunction during myocardial infarction (MI), but the underlying mechanisms have not been fully understood. In this study, we investigated the impact of exercise training on cardiac function, myocardial fibrosis, apoptosis, oxidative stress and mitochondrial biogenesis.&#x0D; Methods Sprague Dawley rats were subjected to MI by permanent ligation of the left anterior descending (LAD) coronary artery or Sham operation. Rats with MI were randomly assigned to sedentary MI group (MI) and MI with exercise training group (MI+EX), and compared to sham-operated group (Sham). Haemodynamics and Masson staining were conducted to evaluate the effect of exercise training on cardiac function and myocardial fibrosis. Myocardial apoptosis, oxidative stress, mitochondrial biogenesis and molecular signaling mechanism were analyzed.&#x0D; Results Exercise training significantly improves cardiac function and mitigates the MI-induced cardiac pathological remodeling. Meanwhile, Exercise training significantly attenuates MI-induced apoptosis, oxidative stress and mitochondrial biogenesis. In addition, activation of PI3K pathway following MI is further induced by exercise training.&#x0D; Conclusions Exercise training protects against MI-induced cardiac dysfunction and pathological remodeling through preventing myocardial apoptosis and oxidative stress, and enhancing mitochondrial biogenesis.

PO-144 Intermittent Exercise Activates NRG1-SERCA2a Pathway to Improve Cardiac Function in Myocardial Infarction Rats

Objective Intermittent exercise can improve cardiac function in rats with myocardial infarction. The Neuregulin-1(NRG1)/SERCA2a palys a critical role in maintain cardiac function. We want to investigate the effect of Neuregulin-1 (NRG1) on NRG1-SERCA2a signaling pathway activated by intermittent exercise and on improves cardiac function in rats with MI.&#x0D; Methods 32 male sprague-dawley rats were randomly divided into four groups (n=8): Sham-operated group (S), sedentary MI group (MI), MI with interval training group (ME), ME with inhibitor AG1478 group (MA). ME and MA model after the MI model was established by ligation of the left anterior descending coronary artery, and began training 1 week after MI surgery. The S model only by threading without ligation. Rats in ME and MA model taken one week adaptive training, then began 8-week interval training. MA model were injected with inhibitor AG1478, once every two days. The 24h after training, rats were anesthetized, the LVSP, LVEDP, ±dp/dt max were tested by carotid artery intubation which in order to evaluate cardiac function. The protein expression of NRG1, PI3K, Akt, eNOS, PKG, PLN, SERCA2a in myocardium were measured by Westernblotting, themRNA expression of serca2a were tested by RT-qPCR.&#x0D; Results Compared with S, the protein expression of NRG1, PKG, peNOS, pAkt, pPLN, pPI3K and SERCA2a decreased, serca2a mRNA expression decreased, LVSP and ±dp/dt max significantly decreased, LVEDP significantly increased; Compared with MI, the protein expression of NRG1, PKG, peNOS, pAkt, pPLN, pPI3K and SERCA2a increased, serca2a mRNA expression increased, LVSP and ±dp/dt max significantly increased, LVEDP decreased, and the effect of exercise were weaken by inhibitor AG1478. Correlation analysis showed that the myocardial pPLN and SERCA2a protein expression both were positively correlated with LVSP, ±dp/dtmax, and negatively correlated with LVEDP.&#x0D; Conclusions Intermittent exercise can increased myocardial NRG1 protein expression and activates NRG1-SERCA2a signaling pathway, improve myocardial infarction cardiac function.

PO-169 Effect of Exercise-Induced Skeletal Muscle FSTL1 on Cardiac Structure and Function in Myocardial Infarction Rats

Objective The aim of this study is to investigate the effect of skeletal muscle-derived FSTL1 on cardioprotection in myocardial infarction rats after resistance exercise or tibialis anterior muscle injection of follistatin-like protein 1 (FSTL1) adeno-associated virus vector and its possible signaling mechanisms.&#x0D; Methods The male Sprague-Dawley rats were randomly divided into five groups (n=10): Sham-operated group(S), sedentary MI group (MI), MI with resistance exercise group (MR), MI with empty adeno-associated virus (AAV) vector group (MV) and MI with FSTL1-AAV group (MF) after the MI model established which was induced by left anterior descending (LAD) coronary artery ligation. S group underwent threading without ligation. 1 week post MI, rats in MR group underwent resistance exercise for 4 weeks, rats in MV and MF group were injected AAV empty vector and FSTL1-AAV in the tibialis anterior muscle of the left limb, respectively. The next day after exercise, rats were anesthetized and heart function was measured. Collagen volume fraction(%) of myocardium were observed and calculated by Masson staining; cardiomyocyte proliferation was measured by immunofluorescence; cardiomyocyte apoptosis was detected by TUNEL staining; The protein expression of skeletal muscle and serum FSTL1 and myocardium FSTL1, DIP2A, pAkt/Akt, p-mTOR/mTOR, CyclinD1, CDK4 and Bcl2/Bax in myocardium were measured by Western blotting.&#x0D; Results The skeletal muscle FSTL1 protein expression was decreased but the serum and myocardium FSTL1 were upregulated in MI group. The myocardium fibrosis, cardiomyocyte proliferation and cardiomyocyte apoptosis were increased and the heart function was declined after MI. After resistance exercise or tibialis anterior muscle injection of FSTL1-AAV, the skeletal muscle, serum and myocardium FSTL1 protein expression were significantly increased, and there was a significant positive correlation between each data. Myocardium fibrosis and cardiomyocyte apoptosis were also decreased, cardiomyocyte proliferation was increased and the heart function was significantly improved after FSTL1-AAV injection.&#x0D; Conclusions Resistance exercise increases skeletal muscle FSTL1 expression. Skeletal muscle-derived FSTL1 can reach the heart through blood circulation, promote cardiomyocyte proliferation, inhibit cardiomyocyte apoptosis, reduce myocardium fibrosis and improve heart function in MI rats. Myocardium FSTL1 binds to its receptor, DIP2A, and activates the Akt-mTOR signaling pathway might be the potential mechanism of this protective effect.