Key role of endothelium in the eNOS-dependent cardioprotection with exercise training

Step count and multiple health outcomes: An umbrella review

OBJECTIVE

This study aimed to quantify the association between step count and multiple health outcomes in a healthy population.

METHODS

PubMed, Embase, Web of Science, and The Cochrane Library were systematically searched for systematic reviews and meta-analyses from inception to April 1, 2022. Literature screening, data extraction, and data analysis were performed in this umbrella review. The intervention factor was daily step counts measured based on devices. Multiple health outcomes included metabolic diseases, cardiovascular diseases, all-cause mortality, and other outcomes in the healthy population.

RESULTS

Twenty studies with 94 outcomes were identified in this umbrella review. The increase in daily step count contributed to a range of human health outcomes. Furthermore, the special population, different age groups, countries, and cohorts should be carefully considered. Negative correlation between step counts and the following outcomes: metabolic outcomes, cardiovascular diseases, all-cause mortality, postural balance, cognitive function, and mental health. However, there was no association between participation in the outdoor walking group and the improvement of systolic blood pressure and diastolic blood pressure. Analysis of the dose-response association between increasing daily step count and the risk of cardiovascular disease events and all-cause mortality showed a substantially linear relationship.

CONCLUSION

A wide range of health outcomes can benefit from the right number of steps.

Ginkgo biloba supplement abates lead-induced endothelial and testicular dysfunction in Wistar rats via up-regulation of Bcl-2 protein expression, pituitary-testicular hormones and down-regulation of oxido-inflammatory reactions

BACKGROUND

Apoptotic and oxido-inflammatory pathways have been found to be up-regulated in lead acetate poisoning which has been associated to endothelial and testicular dysfunctions. It is yet uncertain, nevertheless, if treatment with Ginkgo biloba supplements (GBS), a flavonoid-rich natural product can lessen the adverse effects of lead on endothelial and testicular functions. This study investigated the impact of Ginkgo biloba supplementation on lead-induced endothelial and testicular dysfunctions.

METHODS

The animals were treated with GBS (50 mg/kg and 100 mg/kg orally) for 14 days following oral exposure to lead acetate (25 mg/kg) for 14 days. After euthanasia, blood samples, epididymal sperm, testes, and aorta were collected. The quantities of the hormones (testosterone, follicle stimulating hormone (FSH) and luteinizing hormone (LH), as well as the anti-apoptotic, oxidative, nitrergic, inflammatory markers, were then determined using immunohistochemistry, ELISA, and conventional biochemical methods.

RESULTS

GBS reduced lead-induced oxidative stress by increasing the levels of the antioxidant enzymes catalase (CAT), glutathione (GSH), and superoxide dismutase (SOD), while lowering malondialdehyde (MDA) in endothelium and testicular cells. Normal testicular weight was restored by GBS which also decreased endothelial endothelin-I and increased nitrite levels. TNF-α and IL-6 were decreased while Bcl-2 protein expression was enhanced. Lead-induced alterations in reproductive hormones (FSH, LH, and testosterone) were also restored to normal.

CONCLUSION

According to our result, using Ginkgo biloba supplement prevented lead from causing endothelial and testicular dysfunction by raising pituitary-testicular hormone levels, boosting Bcl-2 protein expression and lowering oxidative and inflammatory stress in the endothelium and testes.

Protective Role of Chronic Exercise Training in Modulating the Impact of Hyperglycemia on Vascular Sensitivity to Ischemia-Reperfusion

Hyperglycemia (HG) is associated with increased mortality and morbidity in acute ischemic events. Regardless of the tissue or organs involved, the vascular endothelium is a key target of ischemia-reperfusion (I/R) injury severity. Among endothelium-protective strategies, exercise has been widely described as useful. However, whether this strategy is able to impact the deleterious effect of HG on endothelial function during I/R has never been challenged. For this, 48 male Wistar rats were randomized into 4 groups: sedentary (Sed) or exercised (Ex, 45 min/day, 5 days/week for 5 weeks) rats, treated (hyperglycemic, HG) or not (normoglycemic, NG) with streptozotocin (40 mg/kg, 48 h before procedure). Vascular I/R (120/15 min) was performed by clamping the femoral artery. Arterial and downstream muscular perfusions were assessed using laser speckle contrast imaging. Vascular endothelial function was assessed in vivo 15 min after reperfusion. HG was responsible for impairment of reperfusion blood flow as well as endothelial function. Interestingly exercise was able to prevent those impairments in the HG group. In agreement with the previous results, HG increased reactive oxygen species production and decreased nitric oxide bioavailability whereas exercise training normalized these parameters. It, therefore, appears that exercise may be an effective prevention strategy against the exacerbation of vascular and muscular damage by hyperglycemia during I/R.

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.

Up-regulation of B-cell lymphoma factor-2 expression, inhibition of oxidative stress and down-regulation of pro-inflammatory cytokines are involved in the protective effect of cabbage (Brassica oleracea) juice in lead-induced endothelial dysfunction in rats

BACKGROUND

Oxido-inflammatory stress and dysregulation of nitric oxide (NO) system has been implicated in lead toxicity. Cabbage is an antioxidant-rich household vegetable with plethora of therapeutic potentials. The present study investigated the anti-oxido-inflammatory activity of cabbage in lead-induced endothelial dysfunction.

METHODS

Twenty (20) male Wistar rats were selected into four groups (n = 5) and treated with distilled water (1 mL/100 g b.wt), lead acetate (25 mg/kg b.wt), cabbage juice (1 mL/100 g b.wt) and lead acetate (25 mg/kg b.wt) plus cabbage juice (1 mL/100 g b.wt) respectively. Treatment was done orally for 28 days, thereafter, oxidative stress (SOD, CAT, GSH, and MDA), inflammatory (TNF-α and IL-6) and apoptotic (Bcl-2) markers were assayed using standard biochemical assays as well as histoarchitectural study of the endothelium.

RESULTS

The results showed that they were significant increase in MDA, ET-1, TNF-α and IL-6 while SOD, GSH, CAT, NO and Bcl-2 protein expression were decreased in Lead exposed animals. Endothelial histoarchitecture was also altered. Following Cabbage juice treatment, MDA, ET-I, TNF-α and IL-6 were down-regulated while SOD, GSH, CAT, NO and Bcl-2 protein expression were up-regulated. Histoarchitecture was significantly recovered.

CONCLUSION

The study suggests that cabbage juice could mitigates Lead-induced endothelial dysfunction by modulating oxido-inflammatory and anti-apoptotic mediators.

DATA AVAILABILITY

All data are available upon request.

Protective effects of trehalose preconditioning on cardiac and coronary endothelial function through eNOS signaling pathway in a rat model of ischemia-reperfusion injury

Coronary endothelial dysfunction is a major cause of ischemia-reperfusion (I/R) injury. Trehalose, a natural disaccharide, has been reported to ameliorate endothelial dysfunction during aging by activating endothelial nitric oxide synthase (eNOS); however, its role in I/R injury is unknown. This study evaluated the effects of trehalose preconditioning on cardiac and coronary endothelial function after I/R. Langendorff-perfused rat hearts underwent 30 min of global ischemia followed by 80 min of reperfusion with or without trehalose preconditioning. Rate pressure product (RPP) and coronary flow (CF) were measured during reperfusion. Perivascular edema was assessed by hematoxylin and eosin staining. Myocardial oxidative stress and apoptosis were evaluated by immunohistochemistry and TUNEL staining, respectively. eNOS dimerization was determined by western blotting. An eNOS inhibitor was used to examine the role of eNOS. Trehalose preconditioning showed a higher recovery rate after I/R as indicated by high RPP (control vs. trehalose, 28 ± 6% vs. 46 ± 9%; P = 0.017, Cohen's d = 2.3) and CF values (35 ± 10% vs. 55 ± 9%; P = 0.025, d = 1.7). Furthermore, trehalose preconditioning reduced perivascular edema, myocardial oxidative stress, and apoptosis. The eNOS dimerization ratio was increased by trehalose (1.2 ± 0.2 vs. 1.6 ± 0.2; P = 0.023, d = 2.1), which was associated with the recovery of RPP and CF. These effects of trehalose were abolished by the eNOS inhibitor. Trehalose preconditioning showed protective effects on cardiac and coronary endothelial function after I/R through the eNOS signaling pathway.

The Effect of Blood Flow-Restricted Low Resistance Training on Microvascular Circulation of Myocardium in Spontaneously Hypertensive Rats

Objective: The purpose of this study was to explore the effect of blood flow-restricted low resistance training on microvascular rarefaction in the myocardium of spontaneously hypertensive rats (SHRs).

Methods: Four-week-old male SHRs were randomly divided into the following groups: Wistar-Kyoto (WKY), SHR control (SHR-SED), high-intensity resistance training (HIRT), low-intensity resistance training (LIRT), and blood flow-restricted low resistance training (BFRT). The exercise groups began to receive exercise intervention for 8 weeks at the age of 7 weeks. Blood pressure (BP), heart rate (HR), cardiac function, capillary density, and Vascular endothelial growth factor -Phosphatidylinositol 3-kinase-Protein kinase B-Endothelial nitric oxide synthetase (VEGF-Pi3k-Akt-eNOS) were assessed.

Results: 1) BP and HR of BFRT decreased significantly, Ejection fraction (EF) and Fraction shortening (FS) increased, and the effect of BFRT on lowering BP and HR was better than that of other groups (p < 0.05); 2) The expression of VEGF, VEGFR2, p-VEGFR2, Pi3k, Akt, p-Akt, eNOS and p-eNOS in the myocardium of the BFRT was significantly upregulated, and eNOS expression was significantly higher than other groups (p < 0 05); 3) the expression of VEGF in the blood of the BFRT was significantly upregulated, higher than SHR-SED, lower than HIRT (p < 0.05), and there was no significant difference between BFRT and LIRT(p > 0.05); 4) the capillary density in the myocardium of BFRT was significantly higher than other exercise groups (p < 0 05).

Conclusion: Blood flow-restricted low resistance training can activate the VEGF-Pi3k-Akt-eNOS pathway, upregulate the expression of VEGF in blood, improve microvascular rarefaction, and promote myocardial microvascular circulation, thereby improving cardiac function and lowering blood pressure, achieving the preventive effect of early hypertension.

Regular aerobic exercise activates PDGF-BB/PDGFR-β signaling and modulates the inflammatory-anti-inflammatory balance in diet-induced obese mice

OBJECTIVE

Regular aerobic exercise induces cardioprotection by counteracting the obesity-associated inflammatory response, dyslipidemia. PDGF-BB/PDGFR-β signaling is established as a crucial mechanism of endothelial cell-cardiomyocyte communication and cardioprotection, but its physiological roles in response to obesity and regular aerobic exercise are unknown.

METHODS

Thirty C57BL/6 mice were divided into three groups: a normal diet group, a high-fat diet group, and a high-fat diet plus aerobic exercise group. Glucose metabolic parameters, inflammation-related indicators, and blood lipids indicators were detected. In addition, gene expression levels of the inflammatory factors, PDGF-BB, PDGFR-β, PI3K, Akt, eNOS, and P53 in cardiac tissue were quantified. Morphological analysis was also used to quantify the magnitude of inflammation.

RESULTS

High-fat diet (HFD) feeding resulted in adiposity, dyslipidemia, and low levels of cardioprotective factors such as APN and eNOS (P < 0.05), which were improved significantly by 8 weeks of aerobic exercise (P < 0.05). HFD feeding increased the gene expression levels of proinflammatory cytokines and decreased the gene expression levels of anti-inflammatory cytokines in cardiac tissue (P < 0.05), which was reversed by regular aerobic exercise (P < 0.05). In addition, HFD feeding suppressed the levels of the cardioprotective factors PDGF-BB and eNOS through PDGF-BB/PDGFR-β/PI3K/Akt/eNOS signaling in cardiac tissue, while regular aerobic exercise activated PDGF-BB/PDGFR-β/PI3K/Akt/eNOS signaling.

CONCLUSION

Regular aerobic exercise improved adiposity, dyslipidemia induced by HFD feeding. Regular aerobic exercise exerted a prominent role in modulating the inflammatory-anti-inflammatory balance and activating the levels of the cardioprotective factors eNOS and PDGF-BB through PDGF-BB/PDGFR-β signaling.

Network analysis of the left anterior descending coronary arteries in swim-trained rats by an in situ video microscopic technique

BACKGROUND

We aimed to identify sex differences in the network properties and to recognize the geometric alteration effects of long-term swim training in a rat model of exercise-induced left ventricular (LV) hypertrophy.

METHODS

Thirty-eight Wistar rats were divided into four groups: male sedentary, female sedentary, male exercised and female exercised. After training sessions, LV morphology and function were checked by echocardiography. The geometry of the left coronary artery system was analysed on pressure-perfused, microsurgically prepared resistance artery networks using in situ video microscopy. All segments over > 80 μm in diameter were studied using divided 50-μm-long cylindrical ring units of the networks. Oxidative-nitrative (O-N) stress markers, adenosine A2A and estrogen receptor (ER) were investigated by immunohistochemistry.

RESULTS

The LV mass index, ejection fraction and fractional shortening significantly increased in exercised animals. We found substantial sex differences in the coronary network in the control groups and in the swim-trained animals. Ring frequency spectra were significantly different between male and female animals in both the sedentary and trained groups. The thickness of the wall was higher in males as a result of training. There were elevations in the populations of 200- and 400-μm vessel units in males; the thinner ones developed farther and the thicker ones closer to the orifice. In females, a new population of 200- to 250-μm vessels appeared unusually close to the orifice.

CONCLUSIONS

Physical activity and LV hypertrophy were accompanied by a remodelling of coronary resistance artery network geometry that was different in both sexes.

Targeting the Endothelium to Achieve Cardioprotection

Despite considerable improvements in the treatment of myocardial infarction, it is still a highly prevalent disease worldwide. Novel therapeutic strategies to limit infarct size are required to protect myocardial function and thus, avoid heart failure progression. Cardioprotection is a research topic with significant achievements in the context of basic science. However, translation of the beneficial effects of protective approaches from bench to bedside has proven difficult. Therefore, there is still an unmet need to study new avenues leading to protecting the myocardium against infarction. In line with this, the endothelium is an essential component of the cardiovascular system with multiple therapeutic targets with cardioprotective potential. Endothelial cells are the most abundant non-myocyte cell type in the heart and are key players in cardiovascular physiology and pathophysiology. These cells can regulate vascular tone, angiogenesis, hemostasis, and inflammation. Accordingly, endothelial dysfunction plays a fundamental role in cardiovascular diseases, which may ultimately lead to myocardial infarction. The endothelium is of paramount importance to protect the myocardium from ischemia/reperfusion injury via conditioning strategies or cardioprotective drugs. This review will provide updated information on the most promising therapeutic agents and protective approaches targeting endothelial cells in the context of myocardial infarction.

Cardiomyocyte-derived small extracellular vesicles can signal eNOS activation in cardiac microvascular endothelial cells to protect against Ischemia/Reperfusion injury

Rationale: The crosstalk between cardiac microvascular endothelial cells (CMECs) and cardiomyocytes (CMs) has emerged as a key component in the development of, and protection against, cardiac diseases. For example, activation of endothelial nitric oxide synthase (eNOS) in CMECs, by therapeutic strategies such as ischemic preconditioning, plays a critical role in the protection against myocardial ischemia/reperfusion (I/R) injury. However, much less is known about the signals produced by CMs that are able to regulate CMEC biology. Here we uncovered one such mechanism using Tongxinluo (TXL), a traditional Chinese medicine, that alleviates myocardial ischemia/reperfusion (I/R) injury by activating CMEC eNOS. The aim of our study is to identify the signals produced by CMs that can regulate CMEC biology during I/R. Methods: Ex vivo, in vivo, and in vitro settings of ischemia-reperfusion were used in our study, with the protective signaling pathways activated in CMECs identified using genetic inhibition (p70s6k1 siRNA, miR-145-5p mimics, etc.), chemical inhibitors (the eNOS inhibitor, L-NNA, and the small extracellular vesicles (sEVs) inhibitor, GW4869) and Western blot analyses. TritonX-100 at a dose of 0.125% was utilized to inactivate the eNOS activity in endothelium to investigate the role of CMEC-derived eNOS in TXL-induced cardioprotection. Results: We found that while CMEC-derived eNOS activity was required for the cardioprotection of TXL, activation of eNOS in CMECs by TXL did not occur directly. Instead, eNOS activation in CMECs required a crosstalk between CMs and CMECs through the uptake of CM-derived sEVs. We further demonstrate that TXL induced CM-sEVs contain increased levels of Long Intergenic Non-Protein Coding RNA, Regulator Of Reprogramming (Linc-ROR). Upon uptake into CMECs, linc-ROR downregulates its target miR-145-5p leading to activation of the eNOS pathway by facilitating the expression of p70s6k1 in these cells. The activation of CMEC-derived eNOS works to increase survival in both the CMECs and the CMs themselves. Conclusions: These data uncover a mechanism by which the crosstalk between CMs and CMECs leads to the increased survival of the heart after I/R injury and point to a new therapeutic target for the blunting of myocardial I/R injury.

Exosomal miR-25-3p from mesenchymal stem cells alleviates myocardial infarction by targeting pro-apoptotic proteins and EZH2

Mesenchymal stem cell (MSC) therapy is a promising approach against myocardial infarction (MI). Studies have demonstrated that MSCs can communicate with other cells by secreting exosomes. In the present study, we aimed to identify exosomal microRNAs that might contribute to MSC-mediated cardioprotective effects. Primary cardiomyocytes were deprived of oxygen and glucose to mimic MI in vitro. For the animal model of MI, the left anterior descending artery was ligated for 1 h, followed by reperfusion for 12 h. MSC-derived exosomes were used to treat primary cardiomyocytes or mice. Cardioprotection-related microRNAs were determined, followed by target gene identification and functional studies with quantitative PCR, western blotting, MTT assay, flow cytometry assay, chromatin immunoprecipitation and dual-luciferase assay. We found that MSC co-culture reduced OGD-induced cardiomyocyte apoptosis and inflammatory responses. Cardioprotection was also observed upon treatment with MSC-derived exosomes in vitro and in vivo. In line with this, exosome uptake led to a significant increase in miR-25-3p in cardiomyocytes. Depletion of miR-25-3p in MSCs abolished the protective effects of exosomes. Mechanistically, miR-25-3p directly targeted the pro-apoptotic genes FASL and PTEN and reduced their protein levels. Moreover, miR-25-3p decreased the levels of EZH2 and H3K27me3, leading to derepression of the cardioprotective gene eNOS as well as the anti-inflammatory gene SOCS3. Inhibition of EZH2 or overexpression of miR-25-3p in cardiomyocytes was sufficient to confer cardioprotective effects in vitro and in vivo. We concluded that exosomal miR-25-3p from MSCs alleviated MI by targeting pro-apoptotic proteins and EZH2.

Cardioprotective effect of sonic hedgehog ligand in pig models of ischemia reperfusion

Sonic hedgehog (SHH) signaling pathway is involved in embryonic tissue patterning and development. Our previous work identified, in small rodent model of ischemia reperfusion, SHH as a specific efficient tool to reduce infarct size and subsequent arrhythmias by preventing ventricular repolarization abnormalities. The goal of the present study was to provide a proof of concept of the cardioprotective effect of SHH ligand in a porcine model of acute ischemia.

Methods: The antiarrhythmic effect of SHH, either by a recombinant peptide (N-SHH) or shed membrane microparticles harboring SHH ligand (MPs^SHH+), was evaluated in a first set of pigs following a short (25 min) coronary artery occlusion (CAO) followed by 24 hours-reperfusion (CAR) (Protocol A). The infarct-limiting effect was evaluated on a second set of pigs with 40 min of coronary artery occlusion followed by 24 hours reperfusion (Protocol B). Electrocardiogram (ECG) was recorded and arrhythmia's scores were evaluated. Area at risk and myocardial infarct size were quantified.

Results: In protocol A, administration of N-SHH 15 min. after the onset of coronary occlusion significantly reduced the occurrence of ventricular fibrillation compared to control group. Evaluation of arrhythmic score showed that N-SHH treatment significantly reduced the overall occurrence of arrhythmias. In protocol B, massive infarction was observed in control animals. Either N-SHH or MPs^SHH+ treatment reduced significantly the infarct size with a concomitant increase of salvaged area. The reduction in infarct size was both accompanied by a significant decrease in systemic biomarkers of myocardial injury, i.e., cardiac troponin I and fatty acid-binding protein and an increase of eNOS activation.

Conclusions: We show for the first time in a large mammalian model that the activation of the SHH pathway by N-SHH or MPs^SHH+ offers a potent protection of the heart to ischemia-reperfusion by preventing the reperfusion arrhythmias, reducing the infarct area and the circulating levels of biomarkers for myocardial injury. These data open up potentially theranostic prospects for patients suffering from myocardial infarction to prevent the occurrence of arrhythmias and reduce myocardial tissue damage.

Long-term exercise results in morphological and biomechanical changes in coronary resistance arterioles in male and female rats

Background

Biomechanical remodeling of coronary resistance arteries in physiological left ventricular hypertrophy has not yet been analyzed, and the possible sex differences are unknown.

Methods

Wistar rats were divided into four groups: male and female sedentary controls (MSe and FSe) and male and female animals undergoing a 12-week intensive swim training program (MEx and FEx). On the last day, the in vitro contractility, endothelium-dependent dilatation, and biomechanical properties of the intramural coronary resistance arteries were investigated by pressure microarteriography. Elastica and collagen remodeling were studied in histological sections.

Results

A similar outer radius and reduced inner radius resulted in an elevated wall to lumen ratio in the MEx and FEx animals compared to that in the sedentary controls. The wall elastic moduli increased in the MEx and FEx rats. Spontaneous and TxA₂ agonist-induced tone was increased in the FEx animals, whereas endothelium-dependent relaxation became more effective in MEx rats. Arteries of FEx rats had stronger contraction, while arteries of MEx animals had improved dilation.

Conclusions

According to our results, the coronary arterioles adapted to an elevated load during long-term exercise, and this adaptation depended on sex. It is important to emphasize that in addition to differences, we also found many similarities between the sexes in the adaptive response to exercise. The observed sport adaptation in the coronary resistance arteries of rats may contribute to a better understanding of the physiological and pathological function of these arteries in active and retired athletes of different sexes.

Cardioprotective effect of the polysaccharide from Ophiopogon japonicus on isoproterenol-induced myocardial ischemia in rats

The polysaccharide (OJP1), extracted from the root of Ophiopogon japonicus, is a well-known traditional Chinese medicine used to treat cardiovascular diseases. The present study was set up to investigate the cardioprotective effect of OJP1 on isoproterenol (ISO)-induced myocardial ischemia injury in rats. Results showed that pretreatment with OJP1 (100, 200 and 300 mg/kg) significantly reduced ISO-induced ST-segment elevation and the heart index, attenuated the levels of marker enzymes (AST, LDH, CK and CK-MB), along with a significantly enhanced the activities of ATPases. Moreover, pretreatment with OJP1 not only enhanced the activities of SOD, GPx and CAT in serum and myocardium, but also decreased the level of MDA. The biochemical and histopathological analysis also showed that OJP1 can alleviate the myocardial injury induced by ISO. Taken together, our results indicated that oral administration of OJP1 offered significant cardioprotective effect against the damage induced by ISO through enhancement of endogenous antioxidants.

A Single Dose of Beetroot Juice Does Not Change Blood Pressure Response Mediated by Acute Aerobic Exercise in Hypertensive Postmenopausal Women

OBJECTIVE

To verify if acute intake of beetroot juice potentiates post-exercise hypotension (PEH) in hypertensive postmenopausal women.

METHODS

Thirteen hypertensive postmenopausal women (58.1 ± 4.62 years and 27.4 ± 4.25 kg/m²) were recruited to participate in three experimental sessions, taking three different beverages: Beetroot juice (BJ), placebo nitrate-depleted BJ (PLA), and orange flavored non-caloric drink (OFD). The participants performed moderate aerobic exercise training on a treadmill, at 65-70% of heart rate reserve (HRR), for 40 min. After an overnight fast, the protocol started at 07h when the first resting blood pressure (BP) was measured. The beverage was ingested at 07h30 and BP was monitored until the exercise training started, at 09h30. After the end of the exercise session, BP was measured every 15 min over a 90-min period. Saliva samples were collected at rest, immediately before and after exercise, and 90 min after exercise for nitrite (NO₂^-) analysis.

RESULTS

There was an increase in salivary NO₂^- with BJ intake when compared to OFD and PLA. A slight increase in salivary NO₂^- was observed with PLA when compared to OFD (p < 0.05), however, PLA resulted in lower salivary NO₂^- when compared to BJ (p < 0.001). There were no changes in salivary NO₂^- with the OFD. Systolic and diastolic BP decreased (p < 0.001) on all post exercise time points after all interventions, with no difference between the three beverages.

CONCLUSION

Acute BJ intake does not change PEH responses in hypertensive postmenopausal women, even though there is an increase in salivary NO₂^-.

Exercise and Cardioprotection: A Natural Defense Against Lethal Myocardial Ischemia-Reperfusion Injury and Potential Guide to Cardiovascular Prophylaxis

Similar to ischemic preconditioning, high-intensity exercise has been shown to decrease infarct size following myocardial infarction. In this article, we review the literature on beneficial effects of exercise, exercise requirements for cardioprotection, common methods utilized in laboratories to study this phenomenon, and discuss possible mechanisms for exercise-mediated cardioprotection.

Resistance exercise mediates remote ischemic preconditioning by limiting cardiac eNOS uncoupling

BACKGROUND

Currently viewed as a complementary non-pharmacological intervention for preventing cardiac disorders, long-term aerobic training produces cardioprotection through remote ischemic preconditioning (RIPC) mechanisms. However, RIPC triggered by acute exercise remains poorly understood. Although resistance exercise (RE) has been highly recommended by several public health guidelines, there is no evidence showing that RE mediates RIPC. Hence, we investigated whether RE induces cardiac RIPC through nitric oxide synthase (NOS)-dependent mechanism.

METHODS AND RESULTS

Acute RE at 40% of the maximal load augmented systemic nitrite levels, associated with increased cardiac eNOS phosphorylation, without affecting nNOS activity. Using an experimental model of myocardial infarction (MI) through ischemia-reperfusion (IR), RE fully prevented the loss of cardiac contractility and the extent of MI size compared to non-exercised (NE) rats. Moreover, RE mitigated aberrant ST-segment and reduced life-threatening arrhythmias induced by IR. Importantly, inhibition of NOS abolished the RE-mediated cardioprotection. After IR, NE rats showed increased cardiac eNOS activity, associated with reduced dimer/monomer ratio. Supporting the pivotal role of eNOS coupling during MI, non-exercised rats displayed a marked generation of reactive oxygen species (ROS) and oxidative-induced carbonylation of proteins, whereas RE prevented these responses. We validated our data demonstrating a restoration of physiological ROS levels in NE + IR cardiac sections treated with BH₄, a cofactor oxidatively depleted during eNOS uncoupling, while cardiac ROS generation from exercised rats remained unchanged, suggesting no physiological needs of supplemental eNOS cofactors.

CONCLUSION

Together, our findings strongly indicate that RE mediates RIPC by limiting eNOS uncoupling and mitigates myocardial IR injury.

The protective effects of acupoint gel embedding on rats with myocardial ischemia-reperfusion injury

AIMS

Prevention and treatment of myocardial ischemia-reperfusion (I/R) injury has for many years been a hot topic in treating ischemic heart disease. As one of the most well-known methods of complementary and alternative medicine, acupuncture has attracted increasing interest in preventing myocardial I/R injury due to its remarkable effectiveness and minimal side effect. However, traditional acupuncture approaches are limited by cumbersome execution, high labor costs and inevitable pain caused by frequent stimulation. Therefore, in this work, we aimed to develop a novel acupoint gel embedding approach and investigated its role in protecting against myocardial I/R injury in rats.

MAIN METHODS

Gels were embedded at bilateral Neiguan (PC6) points of rats and their protective effects against myocardial I/R injury evaluated in terms of changes in histomorphology, myocardial enzymology, antioxidant capacity, anti-inflammatory response, and anti-apoptosis of cells.

KEY FINDINGS

We found that the approach of acupoint gel embedding could significantly reduce myocardial infarcted size, repair pathological changes, mitigate oxidative stress damage and inflammatory response, as well as inhibit apoptosis of cardiomyocytes. Such cardioprotective effects were found to be associated with Notch-1/Jagged-1 signaling pathway.

SIGNIFICANCE

The proposed approach of acupoint gel embedding has advantages in continuous acupoint stimulation, dosing controls, and no side effects in the course of treatment, as well as in reducing the pain caused by frequent acupuncture. It can form an alternative therapy to not only protect against myocardial I/R injury but also hold great potential in treating other diseases in the future.

A randomized controlled trial to evaluate utilization of physical activity recommendations among patients of cardiovascular healthcare centres in Eastern Slovakia: study design and rationale of the AWATAR study

Background

Guidelines on modifiable risk factors regarding cardiological patients are poorly implemented in clinical practice perhaps due to low health literacy. Several digital tools for improving lifestyle and behavioural intervention were developed. Our primary aim is to evaluate the effectiveness of a digital exercise prescription tool on the adherence to physical activity recommendations among patients with cardiovascular diseases.

Methods

A randomized controlled trial will be realized in cooperation with Cardiovascular Health Centres in Eastern Slovakia. Patients recruited through their cardiologists, will be randomised at 1:1 ratio to the three-months’ experimental condition or control condition. The experimental group will receive standard lifestyle consultation leading to individually optimized prescription of physical activity. The control group will receive standard, usual-cardio-care lifestyle counselling, also in the domain of physical activity. The digital system will be used for optimized exercise prescription. The primary outcome is a change in the patient’s adherence to exercise recommendations. Data will be collected in both groups prior to consultation and after 3 months.

Discussion

This study protocol presents background and design of a randomized control trial to investigate the effectiveness of a digital system-provide exercise prescription tool on the adherence to physical activity recommendations. An optimized exercise prescription that better reflects patient’s diagnosis, comorbidities and medication can have a significant impact on secondary prevention of cardiovascular disease. This trial can provide important evidence about the effectiveness of digital exercise guidance in everyday practice of cardiovascular healthcare.

Trial registration

The study was registered on 1st November, 2017 and is available online at ClinicalTrials.gov (ID:NCT03329053).

The opposite effects of nitric oxide donor, S-nitrosoglutathione, on myocardial ischaemia/reperfusion injury in diabetic and non-diabetic mice

Nitric oxide is a potent anti-apoptotic and cardioprotective molecule in healthy animals. However, recent study demonstrates that overexpression of eNOS exacerbates the liver injury in diabetic animals. whether diabetes may also alter NO's biologic activity in ischaemic/reperfused heart remains unknown. The present experiment was designed to determine whether the nitric oxide donor, S-nitrosoglutathione, may exert different effects on diabetic and non-diabetic myocardial ischaemia/reperfusion (MI/R) injury. Diabetic state was induced in mice by multiple intraperitoneal injections of low-dose streptozotocin (STZ). The control or diabetic mice were subjected to 30 minutes ischaemia and 3 or 24 hours reperfusion. At 10 minutes before reperfusion, diabetic and non-diabetic mice were received an intraperitoneal injection of S-nitrosoglutathione (GSNO, a nitric oxide donor, 1 μmol/kg). GSNO attenuated MI/R injury in non-diabetic mice, as measured by improved cardiac function, reduced infarct size and decreased cardiomyocyte apoptosis. In contrast, GSNO failed to attenuate but, rather, aggravated the MI/R injury in diabetic mice. Mechanically, the diabetic heart exhibited an increased nitrative/oxidative stress level, as measured by peroxynitrite formation, compared with non-diabetic mice. Co-administration of GSNO with EUK134 (a peroxynitrite scavenger) or MnTE-2-PyP5 (a superoxide dismutase mimetic) or Apocynin (a NADPH oxidase inhibitor) 10 minutes before reperfusion significantly decreased the MI/R-induced peroxynitrite formation and the MI/R injury. Collectively, the present study for the first time demonstrated that diabetes may cause superoxide overproduction, increase NO inactivation and peroxynitrite formation, and thus convert GSNO from a cardioprotective molecule to a cardiotoxic molecule.

Voluntary exercise training restores anticontractile effect of NO in coronary arteries of adult rats with antenatal/early postnatal hypothyroidism

INTRODUCTION

Our recent study showed that NO-mediated anticontractile effect of endothelium is absent in coronary arteries of adult rats, which suffered from antenatal/early postnatal hypothyroidism. This study tested the hypothesis that exercise training would improve such detrimental consequences of early thyroid deficiency.

DESIGN AND METHODS

Wistar dams received propylthiouracil (PTU, 7 ppm) in drinking water during gestation and two weeks postpartum; control dams received tap water. Six-week-old male offspring of control (CON) and PTU dams was divided into sedentary (CON-Sed, n = 12; PTU-Sed, n = 10) and trained (CON-Tr, n = 12; PTU-Tr, n = 10) groups; the latter had 24-h access to running wheels. Eight weeks later coronary arteries were studied by wire myography. Anticontractile effect of NO was assessed by the effects of NOS inhibitor L-NNA on the basal tone and contractile response to U46619. Oxidative phosphorylation complexes and eNOS were estimated by Western blotting.

RESULTS

T₃/T₄ and TSH levels (ELISA) were normalized in the progeny of PTU-treated dams at the age of 6 weeks and were not affected by training. Total running distance did not differ between CON-Tr and PTU-Tr. The contents of oxidative phosphorylation complexes were increased post-training in triceps brachii muscle from CON-Tr and PTU-Tr and in heart from PTU-Tr. Coronary arteries of PTU-Sed compared to CON-Sed demonstrated higher basal tone and contractile response to U46619, which were not further increased by L-NNA. The effects of L-NNA on the basal tone and contractile response to U46619 did not differ in CON-Tr and PTU-Tr groups, but were elevated in PTU-Tr compared to PTU-Sed group. PTU-Tr rats in comparison to PTU-Sed group had higher eNOS content in heart. Responses of coronary arteries to DEA/NO did not differ among all experimental groups.

CONCLUSIONS

Long-lasting coronary endothelial dysfunction resulted from transient thyroid deficiency during the antenatal/early postnatal period can be corrected by voluntary exercise training.

Myrtenol protects against myocardial ischemia-reperfusion injury through antioxidant and anti-apoptotic dependent mechanisms

Myrtenol is a monoterpene with multiple pharmacological activities. However, although monoterpenes have been proposed to play beneficial roles in a variety of cardiac disorders, pharmacological actions of myrtenol in the heart are not yet reported. Hence, the aim of this study was to evaluate whether myrtenol promotes cardioprotection against myocardial ischemia-reperfusion (IR) injury, and the mechanisms involved in these effects. Male Wistar rats were orally treated for seven consecutive days with myrtenol (50 mg/kg) or N-acetyl cysteine (1.200 mg/kg, NAC). Afterward, hearts were subjected to myocardial IR injury. Here, we show that the severe impairment of contractile performance induced by IR was significantly prevented by myrtenol or NAC. Moreover, myrtenol abolished aberrant electrocardiographic waveform (ST-segment elevation), as well as reduced life-threatening arrhythmias and infarct size induced by IR injury. Importantly, myrtenol fully prevented the massive increase of cardiac reactive oxygen species generation and oxidative stress damage. Accordingly, myrtenol restored the impairment of endogenous antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase and reductase) activities and balance of pro- and anti-apoptotic pathways (Bax and Bcl-2), associated with decreased apoptotic cells. Taken together, our data show that myrtenol promotes cardioprotection against IR injury through attenuation of oxidative stress and inhibition of pro-apoptotic pathway.