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Objective. To investigate whether exercise preconditioning (EP) improves the rat cardiac dysfunction induced by exhaustive exercise (EE) through regulating NOD-like receptor protein 3 (NLRP3) inflammatory pathways and to confirm which intensity of EP is better. Method. Ninety healthy male Sprague Dawley rats were randomly divided into five groups: a control group (CON), exhaustive exercise group (EE), low-, middle-, and high-intensity exercise precondition and exhaustive exercise group (LEP + EE, MEP + EE, HEP + EE group). We established the experimental model by referring to Bedford's motion load standard to complete the experiment. Then, the pathological changes of the myocardium were observed under a light microscope. Biomarker of myocardial injury in serum and oxidative stress factor in myocardial tissue were evaluated by ELISAs. The cardiac function parameters were detected using a Millar pressure and volume catheter. The levels of thioredoxin-interacting protein (TXNIP), thioredoxin protein (TRX), nuclear transcription factor kappa Bp65 (NF-ĸBp65), NLRP3, and cysteinaspartate specific proteinase 1 (Caspase-1) protein in rats' myocardium were detected by western blotting. Results. 1. The myocardial structures of three EP + EE groups were all improved compared with EE groups. 2. The levels of the creatine phosphating-enzyme MB (CK-MB), reactive oxygen species (ROS), interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor alpha (TNF-α) in three EP + EE groups were all increased compared with CON but decreased compared with the EE group (P < 0.05). 3. Compared with the CON group, slope of end-systolic pressure volume relationship (ESPVR), ejection fraction (EF), and peak rate of the increase in pressure (dP/dtmax) all dropped to the lowest level in the EE group (P < 0.05), while the values of cardiac output (CO), stroke volume (SV), end-systolic volume (Ves), end-diastolic volume (Ved), and relaxation time constant (Tau) increased in the EE group (P < 0.05). 4. Compared with the CON group, the expression levels of TXNIP, NF-ĸBp65, NLRP3, and Caspase-1 all increased obviously in the other groups (P < 0.05); meanwhile, they were all decreased in three EP + EE groups compared with the EE group (P < 0.05). 5. NLRP3 was positively correlated with heart rate, IL-6, and ROS, but negatively correlated with EF (P < 0.01). Conclusion. EP protects the heart from EE-induced injury through downregulating TXNIP/TRX/NF-ĸBp65/NLRP3 inflammatory signaling pathways. Moderate intensity EP has the best protective effect. [ABSTRACT FROM AUTHOR]

Objective. To investigate whether exercise preconditioning (EP) protects the rat heart from exhaustive exercise- (EE-) induced injury by inducing the PI3K-Akt signaling pathway. Methods. 84 male Sprague-Dawley rats were randomly divided into 6 groups (n = 14 rats per group): control group (Con), exhaustive exercise group (EE), exercise preconditioning group (EP), exercise preconditioning + exhaustive exercise group (EP + EE), LY294002 (PI3K inhibitor) + exercise preconditioning + exhaustive exercise group (LY + EP + EE), and LY294002 group (LY). The Con and LY did not exercise. The remaining groups were subjected to treadmill running. The structure of myocardial tissue and serum biomarkers of myocardial injury were observed. Hemodynamic parameters were recorded with a pressure-volume catheter. TUNEL assay was used to detect the apoptosis of cardiac myocytes, and the level of mitochondrial membrane permeability transforming pore (mPTP) in myocardium was evaluated using ELISA. Pathway and apoptosis-related proteins in myocardium were assessed using western blotting. Results. Compared to the Con group, the EE group showed remarkable myocardial injury, such as cardiac dysfunction and myocardial apoptosis. Compared to the EE group, the injuries in the EP + EE group were improved. EP increased the PI3K-Akt signaling pathway and regulated Bcl-2 family to decrease the mPTP openness level. However, the cardioprotective effects of EP were attenuated when pretreated with the LY294002. Conclusions. EP protected the heart from EE-induced injury, and it may improve the cardiac function and reduce the cardiomyocyte apoptosis by activating the PI3K-Akt signaling pathway. [ABSTRACT FROM AUTHOR]

Pharmacological antiarrhythmic therapy such as beta-blockers in patients with frequent premature ventricular contractions (PVCs) and concomitant bradycardia is challenging. A traditional Chinese medicine, Shensong Yangxin (SSYX), has been effective in treatment of frequent PVCs and sinus bradycardia (SB) in separate patient cohorts. This double-blind, placebo-controlled, multicentre, randomized clinical trial investigates the acute efficacy of SSYX in reducing PVCs burden in patients with concomitant SB. Patients with symptomatic, frequent PVCs, and SB, defined as mean heart rate (MHR) of 45 to 59 beats per min (bpm), were recruited at 33 medical centres in mainland China and randomly assigned by computer to either SSYX or matching placebo for eight weeks. Patients, investigators, and trial personnel were masked to treatment allocation. Primary endpoints were changes in PVCs burden and MHR as assessed by 24-hour Holter monitoring relative to baseline. Secondary efficacy endpoints were subjective symptom score, ECG, and biochemical parameters. Analysis was based on intention-to-treat principles. 333 patients were randomized, of which 166 received SSYX and 167 placebo. Baseline characteristics did not differ. SSYX reduced PVCs burden by 68.2% (p < 0.001) and increased MHR by 10.9% (p < 0.001) compared to 32.2% and 4.7%, respectively, in the placebo group. SSYX group experienced greater symptomatic improvement (p < 0.001). No differences in reported adverse events were seen (20 versus 23). SSYX is an effective antiarrhythmic therapy for symptomatic, frequent PVCs uniquely suited patients with concomitant SB. Clinical trial number was NCT01750775. [ABSTRACT FROM AUTHOR]