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Background: The phrase "dysfunctional high-density lipoprotein" has been developed in the literature to describe the particle which loses its basic role- anti-oxidative and anti-inflammatory activity. In this porcess, the significance of enzymes- pro-oxidant myeloperoxidase (MPO) and antioxidant paraoxonase-1 (PON-1) from the perspective of HDL-C function has been noted., Aims: The objective of this study was to analyze the associations between two enzymes -MPO and PON-1 and type 2 diabetes (T2DM) in patients with ischemic heart disease (IHD)., Methods: An observational cross-sectional study including 70 patients with IHD of whom 35 had also T2DM, and 35 had no T2DM. Laboratory tests (MPO, PON-1, fasting glucose, glycated hemoglobin, total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, and high-sensitivity C-reactive protein) were performed., Results: The study revealed a significant difference in the serum concentration of the enzymes between patients with IHD with and without T2DM. Our results showed increased MPO concentration levels in diabetic patients. The analysis also revealed that T2DM is independently associated with an increase in MPO levels. Simultaneously, a decrease in PON-1 levels was observed in patients with T2DM. The study also revealed that T2DM is independently associated with a decrease in PON-1 levels., Conclusions: In patients with type 2 diabetes the profile of enzymes involved in high-density lipoprotein metabolism in patients with IHD is worse than in patients without T2DM. The increase in the levels of MPO, an enzyme with oxidative and atherogenic properties and on a decrease in PON-1 levels, an enzyme with antioxidant and atheroprotective properties is observed., (© 2022. The Author(s).)

Heme oxygenase-1 (HO-1), an inducible stress-response protein, exerts anti-oxidant and anti-apoptotic effects. However, its significance in forensic diagnosis of acute ischemic heart diseases (AIHD) such as myocardial infarction (MI) is still unknown. We examined the immunohistochemical expression of HO-1 in the heart samples to discuss their forensic significance to determine acute cardiac ischemia. The heart samples were obtained from 23 AIHD cases and 33 non-AIHD cases as controls. HO-1 positive signals in cardiomyocyte nuclear were detected in 78.2% of AIHD cases, however, that were detected in only 24.2% control cases with statistical difference between AIHD and non-AIHD groups. In contrast to HO-1 protein expression, there was no significant difference in the appearance of myoglobin pallor regions and leukocyte infiltration in the hearts between AIHD and non-AIHD groups. From the viewpoints of forensic pathology, intracardiac HO-1 expression would be considered a valuable marker to diagnose AIHD as the cause of death., (© 2021. The Author(s).)

Yorkshire swine were fed standard diet ( n = 7) or standard diet containing applesauce rich in caffeic acid with Lactobacillus plantarum ( n = 7) for 3 wk. An ameroid constrictor was next placed around the left coronary circumflex artery, and the dietary regimens were continued. At 14 wk, cardiac function, myocardial perfusion, vascular density, and molecular signaling in ischemic myocardium were evaluated. The L. plantarum -applesauce augmented NF-E2-related factor 2 (Nrf2) in the ischemic myocardium and induced Nrf2-regulated antioxidant enzymes heme oxygenase-1 (HO-1), NADPH dehydrogenase quinone 1 (NQO-1), and thioredoxin reductase (TRXR-1). Improved left ventricular diastolic function and decreased myocardial collagen expression were seen in animals receiving the L. plantarum -applesauce supplements. The expression of endothelial nitric oxide synthase (eNOS) was increased in ischemic myocardial tissue of the treatment group, whereas levels of asymmetric dimethyl arginine (ADMA), hypoxia inducible factor 1α (HIF-1α), and phosphorylated MAPK (pMAPK) were decreased. Collateral-dependent myocardial perfusion was unaffected, whereas arteriolar and capillary densities were reduced as determined by α-smooth muscle cell actin and CD31 immunofluorescence in ischemic myocardial tissue. Dietary supplementation with L. plantarum -applesauce is a safe and effective method of enhancing Nrf2-mediated antioxidant signaling cascade in ischemic myocardium. Although this experimental diet was associated with a reduction in hypoxic stimuli, decreased vascular density, and without any change in collateral-dependent perfusion, the net effect of an increase in antioxidant activity and eNOS expression resulted in improvement in diastolic function. NEW & NOTEWORTHY Colonization of the gut microbiome with certain strains of L. Plantarum has been shown to convert caffeic acid readily available in applesauce to 4-vinyl-catechol, a potent activator of the Nrf2 antioxidant defense pathway. In this exciting study, we show that simple dietary supplementation with L. Plantarum -applesauce-mediated Nrf2 activation supports vascular function, ameliorates myocardial ischemic diastolic dysfunction, and upregulates expression of eNOS.

Inflammasome-promoted sterile inflammation following cardiac damage is critically implicated in heart dysfunction after myocardial infarction (MI). Glycogen synthase kinase-3 (GSK-3β) is a prominent mediator of the inflammatory response, and high GSK-3 activity is associated with various heart diseases. We investigated the regulatory mechanisms of GSK-3β in activation of the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in a rat model with successful induction of MI on days 2-28. An in vitro investigation was performed using newborn rat/human cardiomyocytes and fibroblast cultures under typical inflammasome stimulation and hypoxia treatment. GSK-3β inhibition markedly improved myocardial dysfunction and prevented remodeling, with parallel reduction in the parameters of NLRP3 inflammasome activation after MI. GSK-3β inhibition reduced NLRP3 inflammasome activation in cardiac fibroblasts, but not in cardiomyocytes. GSK-3β's interaction with activating signal cointegrator (ASC) as well as GSK-3β inhibition reduced ASC phosphorylation and oligomerization at the tissues and cellular levels. Taken together, these data show that GSK-3β directly mediates NLRP3 inflammasome activation, causing cardiac dysfunction in MI., (Copyright © 2020. Published by Elsevier Ltd.)

Proprotein convertase subtilisin/Kexin type 9 (PCSK9) and pyroptosis both play important roles in myocardial infarction. This study was designed to test the hypothesis that PCSK9 regulates pyroptosis in cardiomyocytes during chronic myocardial ischemia. Primary cardiomyocytes were isolated from WT and PCSK9 -/- mice. HL-1 cardiomyocytes were used to set up PCSK9-deficient (PCSK9 -/- ) and PCSK9-upregulated (PCSK9 CRISPRa ) cardiomyocyte cell line with CRISPR/Cas9 knockout or activation plasmid. Additional studies were performed with chronic myocardial ischemia in WT and PCSK9 -/- mice. We observed that PCSK9 initiates mitochondrial DNA (mtDNA) damage, activates NLRP3 inflammasome signaling (NLRP3, ASC, Caspase-1, IL-1β, and IL-18), and subsequently induces Caspase-1-dependent pyroptosis. There was an intense expression of PCSK9 and pyroptosis marker, GSDMD-NT, in the zone bordering the infarct area. PCSK9 -/- significantly suppressed expression of NLRP3 inflammasome signaling, GSDMD-NT, and LDH release. Furthermore, serum levels of PCSK9, NLPR3 inflammasome signaling, and pyroptosis (GSDMD and LDH release) were significantly elevated in patients with chronic myocardial ischemia as compared to those in age-matched healthy subjects. Human hearts with recent infarcts also showed high expression of PCSK9 and GSDMD-NT in the border zone similar to that in the infarcted mouse heart. These observations provide compelling evidence for the role of PCSK9 in regulating Caspase-1-dependent pyroptosis via mtDNA damage and may qualify pro-inflammatory cytokines and pyroptosis as potential targets to treat PCSK9-related cardiovascular diseases.

We previously demonstrated that hexokinase II (HK2) dissociation from mitochondria during cardiac ischemia correlates with cytochrome c (cyt-c) loss, oxidative stress and subsequent reperfusion injury. However, whether HK2 release is the primary signal mediating this ischemia-induced mitochondrial dysfunction was not established. To investigate this, we studied the effects of dissociating HK2 from isolated heart mitochondria. Mitochondria isolated from Langendorff-perfused rat hearts before and after 30 min global ischemia ± ischemic preconditioning (IPC) were subject to in vitro dissociation of HK2 by incubation with glucose-6-phosphate at pH 6.3. Prior HK2 dissociation from pre- or end-ischemic heart mitochondria had no effect on their cyt-c release, respiration (± ADP) or mitochondrial permeability transition pore (mPTP) opening. Inner mitochondrial membrane morphology was assessed indirectly by monitoring changes in light scattering (LS) and confirmed by transmission electron microscopy. Although no major ultrastructure differences were detected between pre- and end-ischemia mitochondria, the amplitude of changes in LS was reduced in the latter. This was prevented by IPC but not mimicked in vitro by HK2 dissociation. We also observed more Drp1, a mitochondrial fission protein, in end-ischemia mitochondria. IPC failed to prevent this increase but did decrease mitochondrial-associated dynamin 2. In vitro HK2 dissociation alone cannot replicate ischemia-induced effects on mitochondrial function implying that in vivo dissociation of HK2 modulates end-ischemia mitochondrial function indirectly perhaps involving interaction with mitochondrial fission proteins. The resulting changes in mitochondrial morphology and cristae structure would destabilize outer / inner membrane interactions, increase cyt-c release and enhance mPTP sensitivity to [Ca2+]., Competing Interests: The authors have declared that no competing interests exist.

Background: We have previously shown that the deficiency of the gut enzyme intestinal alkaline phosphatase (IAP) is associated with type 2 diabetes mellitus (T2DM) in humans, and mice deficient in IAP develop the metabolic syndrome, a precipitant of T2DM and ischemic heart disease (IHD). We hypothesized that IAP deficiency might also be associated with IHD in humans. We aimed to determine the correlation between the IAP level and IHD in humans., Methods and Results: The IHD patients were recruited from the National Institute of Cardiovascular Diseases (NICVD), Dhaka, Bangladesh, and the control healthy participants were recruited from a suburban community of Dhaka. We determined the IAP level in the stools of 292 IHD patients (187 males, 105 females) and 331 healthy control people (84 males, 247 females). We found that compared to controls, IHD patients have approx. 30% less IAP (mean ± SEM: 63.7 ± 3.5 vs. 44.9 ± 2.1 U/g stool, respectively; p < 0.000001), which indicates that IAP deficiency is associated with IHD, and a high level of IAP is probably protective against IHD in humans. The adjusted generalized linear model (GLM) of regression analysis predicted a strong association of IAP with IHD ( p = 0.0035). Multiple logistic regression analysis showed an independent inverse relationship between the IAP level and the IHD status (odds ratio, OR = 0.993 with 95% CI 0.987-0.998; p < 0.01)., Conclusions: IAP deficiency is associated with IHD, and a high level of IAP might be protective against IHD., Competing Interests: The authors declare no conflict of interests., (Copyright © 2019 Jagannath Malo et al.)

Myocardial infarction due to coronary artery occlusion leads to adverse cardiac remodeling and heart failure. Apoptotic loss of cardiomyocytes near the ischemia area enlarges infarct area and promotes cardiac remodeling. Protein arginine methyltransferase 4 (PRMT4), a type I protein arginine methyltransferase, is involved in many cellular processes. Here we aimed to investigate the role of PRMT4 in cardiomyocyte apoptosis and myocardial infarction. We found that PRMT4 expression was markedly increased in ischemic heart and hypoxic cardiomyocytes. In vivo, cardiac-specific overexpression of PRMT4 in mice resulted in decreased survival rate, reduced left ventricular function, and aggravated cardiac remodeling following myocardial infarction. Mechanistically, PRMT4 overexpression promoted hypoxia-induced cardiomyocytes apoptosis, while its inhibition abolished these effects. Taken together, our work suggested an essential role of PRMT4 in myocardial infarction and cardiomyocyte apoptosis., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Ventricular remodeling is a major pathological process of normal heart failure. With the aging of society, poor diet control, social, psychological and other risk factors in our country, the incidence of myocardial infarction and hypertension is reported to increase yearly. Many treatment methods have effectively delayed the occurrence of ventricular remodeling. However, in order to prevent and delay the occurrence and development of ventricular remodeling, the new treatment strategy cannot be ignored., Methods: In this study, we used male C57BL/6 mice (8 weeks old), weight 23 g-27 g, SPF grade. According to the established methods of the research group, the left anterior descending branch of the coronary artery (LAD) was used to make the model of myocardial ischemia, and which was evaluated by the change of EF value in mice. The experiment included seven groups: sham operation group, model group, metoprolol group, puerarin group, tanshinone IIA group, tanshinone IIA: puerarin =1:1 group, tanshinone IIA: puerarin =1:2 group. The changes of cardiac function in each group were observed by echocardiography and hemodynamics after the drug delivery cycle was 3d, 7d, 14d and 28d. Detection of 3d serum enzyme indexes LDH, CK and CK-MB by automatic biochemical analyzer. The expression of CD11b, F4/80, Ly6C in cardiac tissues were detected by flow cytometry at 3d and 7d. The expression of IL-1β and TNF- α in serum were detected by ELISA. IL-1β, IL-6, IL-10, iNOS and other related genes were detected by RT-PCR method. HE, Masson staining and immunohistochemical staining were used to observe the changes of myocardial histomorphology in mice. We also examined the effects of different drug treatments on the proliferation and function of Raw264.7 cells, H9C2 cells and HUVECs. Western blot examined the effects of different drug treatments on the expression of inflammatory pathway related proteins TLR4 and C/EBP-β., Results: 1. Echocardiographic results showed that with the prolongation of ischemic time, the ejection fraction of the model group, the shortening rate of the short axis of the left ventricle, the flow rate of the outflow tract were significantly decreased, and the structure of the ventricle was significantly changed. Hemodynamic tests showed that the maximum and maximum rate of decline in the post-ischemia model group were significantly reduced, with increased systolic and diastolic volume, and a decrease in pressure difference. After treatment with drugs, all groups improved, but tanshinone IIA: puerarin = 1:1 group can significantly improve the above indicators after 28d of administration, which can effectively relieve the deterioration of cardiac function caused by acute myocardial infarction. 2. After administration for 3 and 7 days, the inflammatory cell CD11b monocytes and the F4/80 phenotype macrophages in heart tissue were detected by flow cytometry, and it was found that tanshinone IIA: puerarin = 1:1 can inhibit the release of inflammatory cells. The results of RT-PCR showed that the tanshinone IIA: puerarin = 1:1 group significantly improved the expression of inflammatory cytokines such as IL-1β, IL-6, IL-10, and iNOS. In the immunohistochemical analysis of iNOS and Arg-1, the tanshinone IIA and puerarin 1:1 treatment group was able to inhibit the expression of M1 macrophages in the early stage of inflammation and promote the expression of M2 macrophages. 3. The cardiac index increased significantly and the serum TGF-β increased after 28d. The combination of tanshinone IIA and puerarin could significantly reduce these indexes. HE, Masson, Sirius red and immunohistochemical staining were found in the combination of tanshinone IIA and puerarin can significantly reduce the structure of acute ischemic myocardial cell damage and interstitial edema, reduce collagen synthesis, and fibroblasts release, thereby inhibiting myocardial fibrosis and heart remodeling. 4. MTT assay showed a significantly greater proliferation of above two cells types treated with tanshinone IIA: puerarin =1:1 and more nodes and meshes were found in tanshinone IIA: puerarin =1:1 group compared with other groups. 5. The combination of tanshinone IIA and puerarin could regulate inflammation through inhibiting the expression of TLR4 protein, but up-regulating the expression of C/EBP-β protein., Conclusion: The combination of tanshinone IIA and puerarin inhibits the immersion of inflammatory cells. Improving hemodynamics by improving cardiac function, reducing the destruction of cardiac myocytes, reducing collagen synthesis, inhibiting myocardial fibrosis and ventricular remodeling. Through the whole experiment, tanshinone IIA: puerarin = 1:1 is the best., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Impaired sarcoplasmic reticulum (SR) calcium transport ATPase (SERCA) gives rise to Ca 2+ alternans and changes of the Ca2+release amount. These changes in Ca 2+ release amount can reveal the mechanism underlying how the interaction between Ca 2+ release and Ca 2+ uptake induces Ca 2+ alternans. This study of alternans by calculating the values of Ca 2+ release properties with impaired SERCA has not been explored before. Here, we induced Ca 2+ alternans by using an impaired SERCA pump under ischemic conditions. The results showed that the recruitment and refractoriness of the Ca 2+ release increased as Ca 2+ alternans occurred. This indicates triggering Ca waves. As the propagation of Ca waves is linked to the occurrence of Ca 2+ alternans, the "threshold" for Ca waves reflects the key factor in Ca 2+ alternans development, and it is still controversial nowadays. We proposed the ratio between the diastolic network SR (NSR) Ca content (Ca nsr ) and the cytoplasmic Ca content (Ca i ) (Ca nsr /Ca i ) as the "threshold" of Ca waves and Ca 2+ alternans. Diastolic Ca nsr , Ca i , and their ratio were recorded at the onset of Ca 2+ alternans. Compared with certain Ca nsr and Ca i , the "threshold" of the ratio can better explain the comprehensive effects of the Ca 2+ release and the Ca 2+ uptake on Ca 2+ alternans onset. In addition, these ratios are related with the function of SERCA pumps, which vary with different ischemic conditions. Thus, values of these ratios could be used to differentiate Ca 2+ alternans from different ischemic cases. This agrees with some experimental results. Therefore, the certain value of diastolic Ca nsr /Ca i can be the better "threshold" for Ca waves and Ca 2+ alternans., Competing Interests: The authors declare that there are no conflicts of interest., (Copyright © 2019 Jiaqi Liu et al.)

Danshen (salvia miltiorrhiza) and honghua(Carthamus tinctorius) were traditional herb pair with promoting blood circulation and removing blood stasis actions, in China. Both were widely used to treat cardiovascular diseases (CVD) for hundreds years, especially shown definite advantage in the treatment of ischemic heart disease (IHD). However, the mechanism of danshen-honghua herb pair (DHHP) in the treatment of IHD was still unclear. This study was focused on examining the effects and possible mechanisms of DHHP in rats with acute myocardial ischemia induced by isoproterenol (ISO). The results suggested that DHHP significantly ameliorated the myocardial tissue abnormalities, notablely inhibited the elevation of lactate dehydrogenase (LDH), creatine kinase (CK), aspartate aminotransferase (AST), creatinekinase isoenzyme (CK-MB) and cardiac troponin T (CTn-T) in plasma, obviously decreased the plasma levels of Tumor Necrosis Factor α (TNF-α), outstandingly inhibited the reduction of superoxide dismutase (SOD), catalase (CAT) caused by ISO, significantly inhibited the high expression of Bcl-2 assaciated X protein (Bax) and nuclear transcriptionfactor-κBP65 (NF-κBP65) protein, significantly induced the low expression of B-cell lymphoma-2 (Bcl-2) protein in acute myocardial ischemia rats. DHHP can obviously ameliorate hemodynamic parameters. In summary, DHHP can significantly improve myocardial ischemia in acute myocardial ischemia model rats caused by ISO. Anti-free radicals, anti-peroxidation, inhibition of cell apoptosis and anti- inflammation maybe are the potential mechanisms of DHHP anti-myocardial ischemia in acute myocardial ischemia rats in duced by ISO., (Copyright © 2019 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Background: After myocardial infarction (MI), delayed progression or reversal of cardiac remodeling is a prime target to limit advanced chronic heart failure (HF). However, the temporal kinetics of lipidomic and systemic metabolic signaling is unclear in HF. There is no consensus on metabolic and lipidomic signatures that influence structure, function, and survival in HF. Here we use genetic knock out model to delineate lipidomic, and metabolic changes to describe the role of lipoxygenase in advancing ischemic HF driven by leukocyte activation with signs of non-resolving inflammation. Bioactive lipids and metabolites are implicated in acute and chronic HF, and the goal of this study was to define the role of lipoxygenase in temporal kinetics of lipidomic and metabolic reprogramming in HF., Materials and Methods: To address this question, we used a permanent coronary ligation mouse model which showed profound metabolic and lipidomic reprogramming in acute HF. Additionally, we defined the lipoxygenase-mediated changes in cardiac pathophysiology in acute and chronic HF. For this, we quantitated systemic metabolic changes and lipidomic profiling in infarcted heart tissue with obvious structural remodeling and cardiac dysfunction progressing from acute to chronic HF in the survival cohort., Results: After MI, lipoxygenase-derived specialized pro-resolving mediators were quantitated and showed lipoxygenase-deficient mice (12/15LOX -/- ) biosynthesize epoxyeicosatrienoic acid (EETs; cypoxins) to facilitate cardiac healing. Lipoxygenase-deficient mice reduced diabetes risk biomarker 2-aminoadipic acid with profound alterations of plasma metabolic signaling of hexoses, amino acids, biogenic amines, acylcarnitines, glycerophospholipids, and sphingolipids in acute HF, thereby improved survival., Conclusion: Specific lipoxygenase deletion alters lipidomic and metabolic signatures, with modified leukocyte profiling that delayed HF progression and improved survival. Future studies are warranted to define the molecular network of lipidome and metabolome in acute and chronic HF patients., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Aims: Myocardial infarction induces myocardial injury and tissue damage. During myocardial infarction strong cellular response is initiated to salvage the damaged tissues. This response is associated with the induction of different signaling pathways. Of these, the canonical Wnt signaling is increasingly important for its prosurvival cellular role, making it a good candidate for the search of new molecular targets to develop therapies to prevent heart failure in infarcted patients., Methods: Herein we report that GSK3β regulates the canonical Wnt signaling in C57Bl6 mice hearts. GSK3β is a canonical Wnt pathway inhibitor. Using GSK3β inhibitors and inducing myocardial injury (MI) in Lrp5-/- mice model we show that GSK3β phosphorylation levels regulate downstream canonical Wnt pathway genes in the ischemic heart. In the setting of MI, myocardial damage assessment usually correlates with functional and clinical outcomes. Therefore, we measured myocardial injury size in Wt and Lrp5-/- mice in the presence and absence of two different GSK3 inhibitors prior to MI. Myocardial injury was independent of GSK3 inhibitor treatments and GSK3β expression levels., Results: These studies support a central role for GSK3β in the activation of the canonical Wnt pathway in the Wt heart. Although LRP5 is protective against myocardial injury, GSK3β expression levels do not regulate heart damage., Competing Interests: The authors have declared that no competing interests exist.

Tryptophan is an essential amino acid. Indoleamine 2,3-dioxygenase (IDO), the rate-limiting enzyme in the tryptophan-kynurenine pathway, is positively associated with cardiac events, and may be relevant to cancer. We used Mendelian Randomization to obtain unconfounded estimates of the association of IDO1 with ischemic heart disease (IHD), ischemic stroke and their risk factors, all-cancer, cancer of the prostate, lung and bronchus, and breast. We obtained genetic instruments independently and strongly (p-value < 5 × 10 -8 ) predicting plasma IDO1 from a proteome genome-wide association study (GWAS), and applied them to consortia GWAS of the outcomes, including the UK Biobank SOFT CAD GWAS (cases < = 76 014, non-cases < = 264 785) for IHD. Estimates were obtained using inverse variance weighting; with MR-Egger, weighted median and MR-PRESSO as sensitivity analyses. IDO1 was inversely associated with IHD (odds ratio (OR) 0.96 per standard deviation, 95% confidence interval (CI) 0.93 to 1.00, p-value = 0.04), diabetes (OR 0.91, 95% CI 0.85 to 0.97) and prostate cancer (OR 0.96, 95% CI 0.93 to 0.99) with a directionally consistent estimate for stroke (OR 0.98, 95% CI 0.95 to 1.02) but not with blood pressure, or the other cancers considered. IDO1 might be a potential therapeutic target for IHD, diabetes and prostate cancer.

Oxidative stress caused by an imbalance in the formation and removal of reactive oxygen species (ROS) plays an important role in the development of several cardiovascular diseases. ROS originate from various cellular origins; however, the highest amount of ROS is produced by mitochondria. One of the proteins contributing to mitochondrial ROS formation is the adaptor protein p66shc, which upon cellular stresses translocates from the cytosol to the mitochondria. In the present review, we focus on the role of p66shc in longevity, in the development of cardiovascular diseases including diabetes, atherosclerosis and its risk factors, myocardial ischemia/reperfusion injury and the protection from it by ischemic preconditioning. Also, the contribution of p66shc towards cerebral pathologies and the potential of the protein as a therapeutic target for the treatment of the aforementioned diseases are discussed.

A major challenge in developing new treatments for myocardial infarction (MI) is an improved understanding of the pathophysiology of hypoxic tissue damage and the activation of endogenous adaptive programs to hypoxia. Due to the relevance of oxygen in metabolism, molecular adaptation to hypoxia driven by the hypoxia-inducible factors (HIFs) and the HIF-regulating prolyl hydroxylase domain enzymes (PHDs) is pivotal for the survival of cells and tissue under hypoxia. The heart under ischemic stress will extensively rely on these mechanisms of endogenous cardiac protection until hypoxia becomes too severe. In the past, work from several laboratories has provided evidence that inhibition of HIF-regulating PHDs might improve the outcome in ischemic heart disease (IHD) potentially because the adaptive mechanisms are boosted early and vigorously. Here, we review the role of the HIF hydroxylase pathway in IHD and highlight the potential of PHD inhibitors as a new treatment for MI with special regard to acute ischemia, reperfusion, and regeneration of the heart.

The aim of this study was to observe the effects of HIF-1α activation on myocardial I/R in diabetes. Diabetes was induced in an experimental rat model, and regulators of HIF-1α including KC7F2, deferoxamine and ginsenoside Rg1 were administered to observe the changes on diabetic rats. The results demonstrated that HIF-1α activation could effectively reduce myocardial injury following I/R in diabetic hearts via ERK but not MMP-2 signalling pathways. This activation promoted myocardial apoptosis, which was accompanied by modulation of Bax/Bcl-2, caspase-3 and caspase-9 expression following deferoxamine administration. Ginsenoside Rg1 application but not Re can activate HIF-1α, resulting in a similar protectively effect on these pathology processes. Our data demonstrated that ginsenoside Rg1 has a potential therapeutic effect by protecting diabetic hearts after myocardial injury following I/R via HIF-1α activation.

The present work introduces data on studying the activity of pyruvate kinase (PK) and lactate dehydrogenase (LDH) and the state of the cardiovascular system in elderly and senile people who applied to polyclinic "Health zone" in Baku. 60 people on an enzimopatiya and 87 people on a condition of cardiovascular system were examined. The examined persons were found the decreased myocardial blood flow, ischemic heart disease (IHD), against increased PK and LDH. Statistically significant differences in the activity of enzymes depending on gender, age were established, and changes in the bioelectric activity of the heart during an ECG were detected.

Background: Telomeres are known to provide genomic stability and telomere length has been associated with cardiovascular diseases. Moreover, a higher telomerase activity has been shown to be associated with ventricular arrhythmias (VA) in ischemic cardiomyopathy. Increasing evidence suggests that genetic variation in key telomere genes has an impact on telomerase activity. Each copy of the minor allele of SNP rs12696304, at a locus including TERC (telomerase), has been associated with ∼75 base pairs reduction in mean telomere length likely mediated by an effect on TERC expression. We investigated the impact of genetic variation of this SNP on telomerase and its association with VA in ischemic cardiomyopathy patients., Methods and Results: Ninety ischemic cardiomyopathy patients with primary prevention implantable cardioverter defibrillators (ICDs) were recruited. Thirty-five received appropriate ICD therapy for potentially fatal VA (cases), while the remaining 55 patients did not (controls). No significant differences in baseline demographics were seen between the groups. TS was measured by qPCR, telomerase activity by TRAP assay, and SNP genotyping with Taqman probes. Telomerase was highest in C homozygous allele and had a significant association with VA in this group only (C/C,C/G,G/G; P-value 0.04, 0.33, 0.43)., Conclusion: The present study is the first to examine the association between telomerase, a SNP at a locus including TERC, and VA in ischemic cardiomyopathy patients. Homozygosity for C-allele significantly effects telomerase expression and its association with VA in this cohort. Large-scale prospective studies are required to determine if this genetic variation predisposes patients to greater arrhythmic tendency post-MI., (© 2018 Crown copyright. Pacing and Clinical Electrophysiology © 2018 Wiley Periodicals, Inc.)

The response to ischemia/reperfusion and the effects of ischemic post-conditioning (IPC) are sex-dependent, but the mechanisms have not been clarified. Male (M) and female (F) rat hearts isolated and perfused using the Langendorff technique were subject to 30 min of global ischemia (GI) and 60 min reperfusion (R). In IPC hearts, three cycles of 30-sec GI/30-sec R were applied at the beginning of R. Infarct size and myocardial function were assessed. Superoxide production, antioxidant systems, and expressions of phosphorylated forms of serine/threonine kinase (Akt), glycogen synthase kinase 3β (GSK-3β), protein kinase C ε (PKCε), endothelial nitric oxide synthase (eNOS), and apoptosis were measured. In the basal state, superoxide production and apoptosis were lower, and antioxidant systems and phospho-kinase expressions were higher in F rather than in M hearts. After ischemia-reperfusion, infarct size was less in F hearts, and post-ischemic recovery of myocardial function was higher in F rather than in M hearts. Superoxide production, phospho-kinase activity, phospho-eNOS, and apoptosis increased in both sexes while antioxidants decreased in both sexes. After IPC, infarct size, superoxide production, and apoptosis decreased and phospho-eNOS increased in F and M hearts but phospho-kinase expressions and post-ischemic recovery of myocardial function improved only in M hearts. These results show that Akt/GSK-3β/PKCε/eNOS-dependent pathways-mediated superoxide production and apoptosis appear as important factors involved in the observed gender differences., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: This study examined whether the serum PON1 activity is different in patients with ischaemic dilated cardiomyopathy (IDCM) and nonischaemic dilated cardiomyopathy (NDCM) and the relation between the serum PON1 activity and serum pro-BNP levels., Methods and Results: In this study, we enrolled 60 patients with left ventricular systolic failure (New York Heart Association [NYHA] class III-IV) and a left ventricular ejection fraction (EF) < 40% as determined by echocardiography and 30 healthy subjects. The patients with systolic heart failure were divided into two groups: patients with IDCM and patients with NDCM. Blood samples were obtained to measure the serum PON1 activity and the serum pro-BNP levels. The median serum PON1 activities were lower among the patients with IDCM or with NDCM compared with the control subjects (p < .001, p = .043, respectively). Compared with the control subjects, the patients with IDCM or with NDCM had higher serum pro-BNP levels (p < .001, p < .001, respectively). The serum PON1 activity was negatively correlated with the serum pro-BNP levels in patients with IDCM (r = -0.548, p < .001). The area under the ROC curve of the serum PON1 activity was 0.798. Using a serum PON1 activity of 201.3 U/L as a cut-off value, the sensitivity was 86.84% and specificity was 66.67% for the diagnosis of IDCM., Conclusions: In this study, the serum PON1 activity was significantly reduced in the patients with IDCM or with NDCM compared with the control subjects. The serum PON1 activity of the patients with IDCM was negatively correlated with the serum pro-BNP levels.

The tumor suppressor PTEN is a major homeostatic regulator, by virtue of its lipid phosphatase activity against phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], which downregulates the PI3K/AKT/mTOR prosurvival signaling, as well as by its protein phosphatase activity towards specific protein targets. PTEN catalytic activity is crucial to control cell growth under physiologic and pathologic situations, and it impacts not only in preventing tumor cell survival and proliferation, but also in restraining several cellular regeneration processes, such as those associated with nerve injury recovery, cardiac ischemia, or wound healing. In these conditions, inhibition of PTEN catalysis is being explored as a potentially beneficial therapeutic intervention. Here, an overview of human diseases and conditions in which PTEN inhibition could be beneficial is presented, together with an update on the current status of specific small molecule inhibitors of PTEN enzymatic activity, their use in experimental models, and their limitations as research or therapeutic drugs., Competing Interests: The author declares no conflict of interest.

Mammalian STE20-like kinase-1 (Mst1) is a generally expressed apoptosis-promoting kinase and a key bridgebuilder of apoptotic signaling in the etiology of tissue injury. Despite the fact that the biological function of Mst1 and its role in the cell's signalling network have yet to be determined, however, there is a lot of evidence that Mst1 plays an important role in cell death which results from tissue injury. Previous studies have shown that Mst1 is not only a target for some apoptosis- related molecules such as caspase 3 and P53, but also act as an activator of these proteinases to magnify apoptosis signal pathways. This article reviews the role of Mst1 in the signaling pathways which is related with the neuronal cell apoptosis or microglia activation following myocardial and brain injury. Therefore, this work contributes to better understanding of the pathological process of myocardial and brain injury., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Background/aims: Coronary angiogenesis is an important protective mechanism in response to myocardial ischemia in coronary artery disease. However, the underlying mechanisms remain largely unclear. Here, we investigated the role of CaMKII activation in ischemia-induced cardiac angiogenesis., Methods: Repetitive transient ischemia model was established in C57/BL6 mice by daily multiple episodes (3 times/day) of short time (5 min) occlusion of the left anterior descending coronary artery for 7 days. Coronary angiogenesis was detected by immunofluorescent staining. RT-qPCR and Western blot analyses were used to detect the mRNA and protein levels of CaMKII, p-CaMKII and VEGF. Primary cardiac microvascular endothelial cells (CMECs) were isolated to investigate the effects of KN93 on cell proliferation and migration in hypoxic condition., Results: We found that angiogenesis was induced in the ischemic myocardium and suppressed by chronic intraperitoneal injection of CaMKII inhibitor KN93. RT-qPCR and Western blot analyses showed that myocardial ischemia induced an increased expression and autophosphorylation of CaMKII. VEGF expression was increased in the ischemia model but blunted by KN93. Moreover, KN93 suppressed the proliferation and migration of cardiac endothelial cells in hypoxic condition in which the protein expression of CaMKII, p-CaMKII and VEGF was increased., Conclusion: CaMKII is an important mediator for the ischemia-induced coronary angiogenesis, in which CaMKII-triggered VEGF expression plays a key role., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Although beneficial effects of non-secreting intracellular renin (ns-renin) against ischemia have been reported, the precise mechanism remains unclear. In this study, we investigated the roles of ns-renin and mitochondrial extracellular signal-related kinase (ERK) 1/2 on mitochondrial permeability transition pore (mPTP) opening during ischemia in diabetes mellitus (DM) hearts. When isolated hearts from Wistar rats (non-DM hearts) and Goto-Kakizaki rats (DM hearts) were subjected to ischemia for 70 min by left anterior descending coronary artery ligation, DM hearts exhibited higher left ventricular (LV) developed pressure and lower LV end-diastolic pressure than non-DM hearts, suggesting ischemic resistance. In addition, DM hearts showed increased intracellular renin (int-renin, including secreting and non-secreting renin) in the ischemic area, and a direct renin inhibitor (DRI; aliskiren) attenuated ischemic resistance in DM hearts. ERK1/2 was significantly phosphorylated after ischemia in both whole cell and mitochondrial fractions in DM hearts. In isolated mitochondria from DM hearts, rat recombinant renin (r-renin) significantly phosphorylated mitochondrial ERK1/2, and hyperpolarized mitochondrial membrane potential (ΔΨ m ) in a U0126 (an inhibitor of mitogen-activated protein kinases/ERK kinases)-sensitive manner. R-renin also attenuated atractyloside (Atr, an mPTP opener)-induced ΔΨ m depolarization and Atr-induced mitochondrial swelling in an U0126-sensitive manner in isolated mitochondria from DM hearts. Furthermore, U0126 attenuated ischemic resistance in DM hearts, whereas it did not alter the hemodynamics in non-DM hearts. Our results suggest that the increased int-renin during ischemia may inhibit mPTP opening through activation of mitochondrial ERK1/2, which may be involved in ischemic resistance in DM hearts., Competing Interests: The authors declare no conflict of interest.

Ischemic injury represents the most frequent cause of death and disability, and it remains unclear why, of all body organs, the brain is most sensitive to hypoxia. In many tissues, type 4 NADPH oxidase is induced upon ischemia or hypoxia, converting oxygen to reactive oxygen species. Here, we show in mouse models of ischemia in the heart, brain, and hindlimb that only in the brain does NADPH oxidase 4 (NOX4) lead to ischemic damage. We explain this distinct cellular distribution pattern through cell-specific knockouts. Endothelial NOX4 breaks down the BBB, while neuronal NOX4 leads to neuronal autotoxicity. Vascular smooth muscle NOX4, the common denominator of ischemia within all ischemic organs, played no apparent role. The direct neuroprotective potential of pharmacological NOX4 inhibition was confirmed in an ex vivo model, free of vascular and BBB components. Our results demonstrate that the heightened sensitivity of the brain to ischemic damage is due to an organ-specific role of NOX4 in blood-brain-barrier endothelial cells and neurons. This mechanism is conserved in at least two rodents and humans, making NOX4 a prime target for a first-in-class mechanism-based, cytoprotective therapy in the unmet high medical need indication of ischemic stroke., Competing Interests: The authors declare no conflict of interest., (Copyright © 2017 the Author(s). Published by PNAS.)

Myocardial reperfusion injury is a consequence of restoration of blood flow post ischemia. It is a complex process involving an acute inflammatory response activated by cytokines, chemokines, growth factors, and mediated by free radicals, calcium overload leading to mitochondrial dysfunction. Secretory phospholipases (sPLA2) are a group of pro-inflammatory molecules associated with diseases such as atherosclerosis, which increase the risk of reperfusion injury. This acute response leads to breakdown of phospholipids such as cardiolipin, found in the mitochondrial inner membrane, leading to disruption of energy producing enzymes of the electron transport chain. Thus the activation of secretory phospholipases has a direct link to the vascular occlusion and arrhythmia observed in myocardial reperfusion injury. Therapeutic agents targeting sPLA2 are under human trials and many are in the preclinical phase. This article reviews the pathological effects of various groups of secretory phospholipases (I, II, V and X) implicated in myocardial ischemia reperfusion injury and the phospholipase inhibitors under development. Considering the fact that human trials in this class of drugs is limited, sPLA2 as a potential target for drug development is emphasized., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Heart disease remains the leading cause of death globally. Although reperfusion following myocardial ischemia can prevent death by restoring nutrient flow, ischemia/reperfusion injury can cause significant heart damage. The mechanisms that drive ischemia/reperfusion injury are not well understood; currently, few methods can predict the state of the cardiac muscle cell and its metabolic conditions during ischemia. Here, we explored the energetic sustainability of cardiomyocytes, using a model for cellular metabolism to predict the levels of ATP following hypoxia. We modeled glycolytic metabolism with a system of coupled ordinary differential equations describing the individual metabolic reactions within the cardiomyocyte over time. Reduced oxygen levels and ATP consumption rates were simulated to characterize metabolite responses to ischemia. By tracking biochemical species within the cell, our model enables prediction of the cell's condition up to the moment of reperfusion. The simulations revealed a distinct transition between energetically sustainable and unsustainable ATP concentrations for various energetic demands. Our model illustrates how even low oxygen concentrations allow the cell to perform essential functions. We found that the oxygen level required for a sustainable level of ATP increases roughly linearly with the ATP consumption rate. An extracellular O 2 concentration of ∼0.007 mm could supply basic energy needs in non-beating cardiomyocytes, suggesting that increased collateral circulation may provide an important source of oxygen to sustain the cardiomyocyte during extended ischemia. Our model provides a time-dependent framework for studying various intervention strategies to change the outcome of reperfusion., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

The mitochondrial ATP dependent matrix protease, Lon, is involved in the maintenance of mitochondrial DNA nucleoids and degradation of abnormal or misfolded proteins. The Lon protease regulates mitochondrial Tfam (mitochondrial transcription factor A) level and thus modulates mitochondrial DNA (mtDNA) content. We have previously shown that hypoxic stress induces the PKA-dependent phosphorylation of cytochrome c oxidase (CcO) subunits I, IVi1, and Vb and a time-dependent reduction of these subunits in RAW 264.7 murine macrophages subjected to hypoxia and rabbit hearts subjected to ischemia/reperfusion. Here, we show that Lon is involved in the preferential turnover of phosphorylated CcO subunits under hypoxic/ischemic stress. Induction of Lon protease occurs at 6 to 12 h of hypoxia and this increase coincides with lower CcO subunit contents. Over-expression of flag-tagged wild type and phosphorylation site mutant Vb and IVi1 subunits (S40A and T52A, respectively) caused marked degradation of wild type protein under hypoxia while the mutant proteins were relatively resistant. Furthermore, the recombinant purified Lon protease degraded the phosphorylated IVi1 and Vb subunits, while the phosphorylation-site mutant proteins were resistant to degradation. 3D structural modeling shows that the phosphorylation sites are exposed to the matrix compartment, accessible to matrix PKA and Lon protease. Hypoxic stress did not alter CcO subunit levels in Lon depleted cells, confirming its role in CcO turnover. Our results therefore suggest that Lon preferentially degrades the phosphorylated subunits of CcO and plays a role in the regulation of CcO activity in hypoxia and ischemia/reperfusion injury., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Pharmacologic inhibition of nitric oxide production inhibits growth of coronary collateral vessels. Dimethylarginine dimethylaminohydrolase 1 (DDAH1) is the major enzyme that degrades asymmetric dimethylarginine (ADMA), a potent inhibitor of nitric oxide synthase. Here we examined regulation of the ADMA-DDAH1 pathway in a canine model of recurrent myocardial ischemia during the time when coronary collateral growth is known to occur. Under basal conditions, DDAH1 expression was non-uniform across the left ventricular (LV) wall, with expression strongest in the subepicardium. In response to ischemia, DDAH1 expression was up-regulated in the midmyocardium of the ischemic zone, and this was associated with a significant reduction in myocardial interstitial fluid (MIF) ADMA. The decrease in MIF ADMA during ischemia was likely due to increased DDAH1 because myocardial protein arginine N-methyl transferase 1 (PRMT1) and the methylated arginine protein content (the source of ADMA) were unchanged or increased, respectively, at this time. The inflammatory mediators interleukin (IL-1β) and tumor necrosis factor (TNF-α) were also elevated in the midmyocardium where DDAH1 expression was increased. Both of these factors significantly up-regulated DDAH1 expression in cultured human coronary artery endothelial cells. Taken together, these results suggest that inflammatory factors expressed in response to myocardial ischemia contributed to up-regulation of DDAH1, which was responsible for the decrease in MIF ADMA.

Objectives: The Ca/calmodulin-dependent protein kinase II (CaMKII), an arrhythmogenic molecule, is excessively activated in cardiac hypertrophy. Here, we investigated the effect of CaMKII inhibition in isoproterenol (ISO)-induced arrhythmias in hypertrophic mice., Results: ISO induced multiple types of arrhythmias in the hypertrophic mice but not in the normal mice. The QTc intervals were prolonged and the amplitudes of T waves were increased significantly by ISO prior to arrhythmia initiation. Inhibition of CaMKII prevented ISO-induced QTc prolongation and T wave elevation and abrogated arrhythmia induction., Materials and Methods: Pressure-overload cardiac hypertrophy was induced in mice by thoracic aortic banding. Arrhythmias were recorded by electrocardiogram in conscious mice., Conclusions: CaMKII inhibition is effective in suppressing adrenergic activation-induced ventricular arrhythmias in cardiac hypertrophy, of which the ventricular ischemia-induced CaMKII activation plays an important role.

Objective: To investigate the effect of "Jiaji"(EX-B 2)-electroacupuncture(EA) preconditioning on the myocardium and expression of cytochrome P 450 signaling pathways of myocardial cells in myocardial ischemia-reperfusion injury(MI/RI) rats., Methods: Sixty male Wistar rats were randomly divided into sham operation, model, Jiaji, Neiguan(PC 6), Yanglingquan(GB 34) and Quchi(LI 11) groups ( n =10 in each group). MI/RI model was established by occlusion of the descen-ding anterior branch of the left coronary artery. EA preconditioning was respectively applied to EX-B 2, PC 6, GB 34 and LI 11 for 30 min, once daily for 7 days. The ECG-ST segment was detected before and after the modeling. The contents of serum creatine kinase-MB(CK-MB) and lactate dehydrogenase(LDH) were detected by ELISA and microplate method separately. The expression levels of myocardial CYP 450 related genes cyp 1 a 1, cyp 2 b 2, cyp 2 c 11, cyp 4 a 2 were detected by Real-time PCR., Results: Thirty minutes after ligation the changes of ECG-ST segment displacement of the Jiaji group and Neiguan group were signifi-cantly lower than that of the model group( P <0.01), and the change was significantly lower in the Neiguan group than in the model group( P <0.01) 30 minutes after reperfusion. Compared with the sham operation group, the activities of serum CK-MB and LDH were significantly increased in the model group( P <0.01). Compared with the model group, the activities of serum CK-MB and LDH were significantly decreased in the Jiaji, Neiguan and Yanglingquan groups ( P <0.01). Compared with the Jiaji group, the activity of serum LDH was significantly increased in the Quchi group, while the activities of serum CK-MB were significantly increased in the Quchi and Yanglingquan groups ( P <0.05). Compared with the sham operation group, the expression levels of myocardial cyp 1 a 1 and cyp 2 b 2 mRNAs were significantly higher in the model group( P <0.01), while the expression of cyp 2 c 11 mRNA was lower( P <0.01). Compared with the model group, the expression levels of cyp 1 a 1 and cyp 4 a 2 mRNAs were lower in the Jiaji, Neiguan and Yanglingquan groups ( P <0.01), while the expressions of cyp 2 b 2 and cyp 2 c 11 mRNAs were higher( P <0.01). Compared with the Jiaji group, the expression of cyp 1 a 1 mRNA was lower in the Neiguan group, while the expression of cyp 2 b 2 mRNA was higher( P <0.05)., Conclusions: EA preconditioning at Jiaji(EX-B 2) can reduce serum myocardial enzymes of myocardial ischemia-reperfusion rats, lower the ST segment of electrocardiogram, up-regulate myocardial CYP 450 epoxygenase cyp 2 b 2 and cyp 2 c 11 mRNAs expression, down-regulate ω-hydroxylase cyp 1 a 1 and cyp 4 a 2 mRNAs expression, thus play a role in myocardial protection.

We used Mendelian randomization to estimate the causal effects of the liver enzymes, alanine aminotransferase (ALT), alkaline phosphatase (ALP) and gamma glutamyltransferase (GGT), on diabetes and cardiovascular disease, using genetic variants predicting these liver enzymes at genome wide significance applied to extensively genotyped case-control studies of diabetes (DIAGRAM) and coronary artery disease (CAD)/myocardial infarction (MI) (CARDIoGRAMplusC4D 1000 Genomes). Genetically higher ALT was associated with higher risk of diabetes, odds ratio (OR) 2.99 per 100% change in concentration (95% confidence interval (CI) 1.62 to 5.52) but ALP OR 0.92 (95% CI 0.71 to 1.19) and GGT OR 0.88 (95% CI 0.75 to 1.04) were not. Genetically predicted ALT, ALP and GGT were not clearly associated with CAD/MI (ALT OR 0.74, 95% CI 0.54 to 1.01, ALP OR 0.86, 95% CI 0.64 to 1.16 and GGT OR 1.08, 95% CI 0.97 to 1.19). We confirm observations of ALT increasing the risk of diabetes, but cannot exclude the possibility that higher ALT may protect against CAD/MI. We also cannot exclude the possibility that GGT increases the risk of CAD/MI and reduces the risk of diabetes. Informative explanations for these potentially contradictory associations should be sought.

Inhibitors of the ubiquitin-proteasome system improve hemodynamic parameters and decrease the infarct size after ischemia reperfusion. The molecular basis of this protection is not fully understood since most available data report inhibition of the 26 proteasome after ischemia reperfusion. The decrease in cellular ATP levels during ischemia leads to the dissociation of the 26S proteasome into the 19S regulatory complex and the 20S catalytic core, which results in protein degradation independently of ubiquitination. There is scarce information on the activity of the 20S proteasome during cardiac ischemia. Accordingly, the aim of this work was to determine the effects of 30 minutes of ischemia, or 30 min of ischemia followed by 60 minutes of reperfusion on the three main peptidase activities of the 20S proteasome in Langendorff perfused rat hearts. We found that 30 min of ischemia produced a significant increase in the chymotrypsin-like activity of the proteasome, without changes in its caspase-like or trypsin-like activities. In contrast, all three activities were decreased upon reperfusion. Ixazomib, perfused before ischemia at a concentration that reduced the chymotrypsin-like activity to 50% of the control values, without affecting the other proteasomal activities, improved the hemodynamic parameters upon reperfusion and decreased the infarct size. Ixazomib also prevented the 50% reduction in RyR2 content observed after ischemia. The protection was lost, however, when simultaneous inhibition of chymotrypsin-like and caspase-like activities of the proteasome was achieved at higher concentration of ixazomib. Our results suggest that selective inhibition of chymotrypsin-like activity of the proteasome during ischemia preserves key proteins for cardiomyocyte function and exerts a positive impact on cardiac performance after reperfusion.

Aims: The present study investigates the protective effect of partially characterized Tribulus terrestris L. fruit methanol extract against mitochondrial dysfunction in cell based (H9c2) myocardial ischemia model., Main Methods: To induce ischemia, the cells were maintained in an ischemic buffer (composition in mM -137 NaCl, 12 KCl, 0.5 MgCl2, 0.9 CaCl2, 20 HEPES, 20 2-deoxy-d-glucose, pH-6.2) at 37°C with 0.1% O2, 5% CO2, and 95% N2 in a hypoxia incubator for 1h. Cells were pretreated with various concentrations of T. terrestris L. fruit methanol extract (10 and 25μg/ml) and Cyclosporin A (1μM) for 24h prior to the induction of ischemia., Key Findings: Different parameters like lactate dehydrogenase release, total antioxidant capacity, glutathione content and antioxidant enzymes were investigated. Studies were conducted on mitochondria by analyzing alterations in mitochondrial membrane potential, integrity, and dynamics (fission and fusion proteins - Mfn1, Mfn2, OPA1, Drp1 and Fis1). Various biochemical processes in mitochondria like activity of electron transport chain (ETC) complexes, oxygen consumption and ATP production was measured. Ischemia for 1h caused a significant (p≤0.05) increase in LDH leakage, decrease in antioxidant activity and caused mitochondrial dysfunction. T. terrestris L. fruit methanol extract pretreatment was found effective in safeguarding mitochondria via its antioxidant potential, mediated through various bioactives. HPLC of T. terrestris L. fruit methanol extract revealed the presence of ferulic acid, phloridzin and diosgenin., Significance: T. terrestris L. fruit ameliorate ischemic insult in H9c2 cells by safeguarding mitochondrial function. This validates the use of T. terrestris L. against heart disorders., (Copyright © 2016 Elsevier Inc. All rights reserved.)

We measured the serum levels of 8-hydroxydeoxyguanosine (8-OHdG) and investigated whether these levels correlate with incidence of ischemic cardiomyopathy (ICM), and whether these levels correlate with underlying oxidative stress in patients with ICM. Polymerase chain reaction-restriction fragment length polymorphism analysis was performed to assess the prevalence of the Ser/Cys polymorphism in the human 8-oxoguanine glycosylase (hOGG1) gene. We analyzed the samples from 246 ICM cases (the ICM group) and another 246 age- and sex-matched volunteers with normal coronary artery function (the control group). Levels of 8-OHdG in participants' blood samples were 6.7 ± 1.7 and 3.0 ± 0.8 in the ICM and control groups, respectively (p < 0.05). Although there were no differences in allele frequency (p = 0.140), significant differences were present in the genotype distributions (p = 0.002). The Cys/Cys genotype correlated strongly with the risk of developing ICM (odds ratio, 2.2; 95% confidence interval, 1.4-3.3). Treating the Ser/Ser and Ser/Cys genotypes as members of the same group increased the predicted ICM risk for patients carrying the Cys/Cys genotype (odds ratio, 1.9; 95% confidence interval, 1.2-2.9). The serum level of 8-OHdG in the ICM group was higher than that in the control group (p < 0.05) and significantly increased in those carrying the Cys/Cys genotype (8.7 ± 1.7 for the Cys/Cys group, and 4.5 ± 0.8 for the Ser/Ser+Ser/Cys group; p < 0.05). Patients carrying the Cys/Cys genotype had a significantly increased risk of developing ICM. Serum levels of 8-OHdG were significantly increased in patients with ICM., (Copyright © 2016. Published by Elsevier Taiwan.)

Background: Therapeutic strategies aimed at increasing hydrogen sulfide (H2S) levels exert cytoprotective effects in various models of cardiovascular injury. However, the underlying mechanism(s) responsible for this protection remain to be fully elucidated. Nuclear factor E2-related factor 2 (Nrf2) is a cellular target of H2S and facilitator of H2S-mediated cardioprotection after acute myocardial infarction. Here, we tested the hypothesis that Nrf2 mediates the cardioprotective effects of H2S therapy in the setting of heart failure., Methods and Results: Mice (12 weeks of age) deficient in Nrf2 (Nrf2 KO; C57BL/6J background) and wild-type littermates were subjected to ischemic-induced heart failure. Wild-type mice treated with H2S in the form of sodium sulfide (Na2S) displayed enhanced Nrf2 signaling, improved left ventricular function, and less cardiac hypertrophy after the induction of heart failure. In contrast, Na2S therapy failed to provide protection against heart failure in Nrf2 KO mice. Studies aimed at evaluating the underlying cardioprotective mechanisms found that Na2S increased the expression of proteasome subunits, resulting in an increased proteasome activity and a reduction in the accumulation of damaged proteins. In contrast, Na2S therapy failed to enhance the proteasome and failed to attenuate the accumulation of damaged proteins in Nrf2 KO mice. Additionally, Na2S failed to improve cardiac function when the proteasome was inhibited., Conclusions: These findings indicate that Na2S therapy enhances proteasomal activity and function during the development of heart failure in an Nrf2-dependent manner and that this enhancement leads to attenuation in cardiac dysfunction., (© 2016 American Heart Association, Inc.)

Objective: To explore the effects of principal-subordinate acupoints combination on improving myocardial ischemia, and the gene regulatory pathways for the protection of myocardial ischemia., Methods: According to the random number table method, 70 SPF Wistar male rats were divided into a normal group, a model group, a LY294002 group, an insulin-like growth factors-1(IGF-1) group, a Neiguan group, an acupoint combination group and an acupoint combination + LY294002 group, 10 rats in each one. Rats in the normal group were injected with 0.9% NaCl solution, while rats in the remaining groups were treated with abdominal subcutaneous injection of isoroterenol hydrochloride to establish the rat model of myocardial ischemia. Rats in the LY294002 group and IGF-1 group were treated with injection of LY294002 solution and IGF-1 solution for 14 days. Rats in the Neiguan group were treated with electroacupuncture (EA) at "Neiguan" (PC 6) by using Han-200 EA apparatus for 10 min per treatment. Rats in the acupoint combination group were treated with EA at "Neiguan" (PC 6), "Zusanli" (ST 36) and "Guanyuan" (CV 4) by using Han-200 EA apparatus for 10 min per treatment. Rats in the acupoint combination + LY294002 group were treated with LY294002 solution for 14 days, and EA at "Neiguan" (PC 6), "Zusanli" (ST 36) and "Guanyuan" (CV 4) was given before model establishment, once a day for 21 days. EA pretreatment was given before model establishment in all acupuncture groups. The heart rate (HR) and ST segment voltage were detected before and after treatment; the myocardial pathological morphology was observed by HE staining; the expressions of P13K mRNA and Akt mRNA were tested., Results: After modeling, HR and ST segment voltage in all intervention groups were higher than those in the normal group (all P < 0.01); after the intervention, the HR and the ST segment voltage in the acupoint combination group, IGF-1 group and IGF-1 group were improved (P < 0.01, P < 0.05), which was more significant in the acupoint combination group and Neiguan group (all P < 0.01). As for the myocardial pathological morphology, obvious myocardial ischemia was observed in the model group, and that in the LY294002 group was the most serious, and that in the acupoint combination+ LY294002 group was moderate. After intervention, the myocardial pathological damage in the IGF-1 group, Neiguan group and acupoint combination group was significant improved, which was more significant in the IGF-1 group and acupoint combination group. As for the expression of PI3K mRNA and Akt mRNA, compared with normal group, the expression of PI3K mRNA was increased in the remaining groups after modeling (P < 0.01, P < 0.05), which was more significant in the IGF-1 group and acupoint combination group (all P < 0. 01). The expression of Akt mRNA in the LY294002 group and acupoint combination + LY294002 group was reduced (P < 0. 01, P < 0.05), while that in the remaining groups was increased (P < 0.01, P < 0.05), which was more significant in the IGF-1 group and acupoint combination group (all P < 0.01)., Conclusion: The principal-subordinate acupoints combination could improve heart rate and ST segment voltage in rats with chronic myocardial ischemia, reduce myocardial pathological damage, which is superior to single selection of "Neiguan" (PC 6). The PI3K/Akt signaling pathway may be involved in the regulation mechanism of principal-subordinate acupoints combination for the protection of chronic myocardial ischemia.

Adenosine triphosphate (ATP) acts on P2X receptors to initiate signal transmission. P2X7 receptors play a role in the pathophysiological process of myocardial ischemic injury. Long noncoding RNAs (lncRNAs) participate in numerous biological functions independent of protein translation. LncRNAs are implicated in nervous system diseases. This study investigated the effects of NONRATT021972 small interference RNA (siRNA) on the pathophysiologic processes mediated by P2X7 receptors in stellate ganglia (SG) after myocardial ischemic injury. Our results demonstrated that the expression of NONRATT021972 in SG was significantly higher in the myocardial ischemic (MI) group than in the control group. Treatment of MI rats with NONRATT021972 siRNA, the P2X7 antagonist brilliant blue G (BBG), or P2X7 siRNA improved the histology of injured ischemic cardiac tissues and decreased the elevated concentrations of serum myocardial enzymes, creatine kinase (CK), CK isoform MB (CK-MB), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) compared to the MI rats. NONRATT021972 siRNA, BBG, or P2X7 siRNA treatment in MI rats decreased the expression levels of P2X7 immunoreactivity, P2X7 messenger RNA (mRNA), and P2X7 protein, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) in the SG compared to MI rats. NONRATT021972 siRNA treatment prevented the pathophysiologic processes mediated by P2X7 receptors in the SG after myocardial ischemic injury.

Objective: To observe the protective effect of electroacupuncture (EA) intervention on the expression of brain-derived-neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) proteins and genes in the hippocampus areas in myocardial ischemia (MI) rats, so as to reveal its underlying mechanisms in protecting hippocampal cells under MI., Methods: Eighty healthy male SD rats were randomized into sham-operation (sham), MI model, Shenmen (HT 7), HT 7-Zhizheng (SI 7) and HT 7-Xinshu (BL 15) groups (n = 15 in each group). The MI model was established by occlusion of the anterior descending branch of the left coronary artery. EA (2 Hz, 2 mA) was applied to bilateral HT 7, HT 7-SI 7, and HT 7-BL 15, respectively for 15 min, once per day for a week. The number of BDNF and its receptor TrkB positive cells in the left hippocampus and that of mRNAs in the right hippocampus tissue were determined by immunohistochemistry and real-time fluorescence quantitative PCR, respectively., Results: In comparison with the sham group, the numbers of both BDNF and TrkB positive cells in the left hippocampus and the expression levels of BDNF mRNA and TrkB mRNA in the right hippocampus were increased slightly (P > 0.05). After EA intervention, the numbers of hippocampal BDNF and TrkB positive cells and the expression levels of BDNF mRNA and TrkB mRNA were evidently up-regulated (P < 0.05, P < 0.01), and the effects of HT 7-SI 7 and HT 7-BL 15 were obviously superior to those of simple HT 7 in up-regulating BDNF and TrkB expression (P < 0.01, P < 0.05). No significant differences were found between the HT 7-SI 7 and HT 7-BL 15 groups in increasing the number of hippocampal BDNF and TrkB positive cells and in up-regulating expression of both BDNF mRNA and TrkB mRNA (P > 0.05)., Conclusion: EA intervention is effective in increasing the expression of hippocampal BDNF and TrkB in MI rats, which may contribute to its effect in protecting hippocampal cells from injury under MI condition. The effect of EA stimulation of HT 7-SI 7 and HT 7-BL 15 was obviously superior to that of simple HT 7 in up-regulating BDNF and TrkB expression.

Background: The aim of this study was to investigate Paraoxanase 1 (PON-1) activity in patients with ST-elevated and non-ST-elevated acute myocardial infarction (AMI) and to determine its correlation with Gensini scores (GSs)., Methods: A total of 109 patients with AMI and 58 healthy subjects as control group were included in the study. Patients were divided into 2 subgroups as ST-elevated and non-ST-elevated AMI patients (Group I and II, respectively). Controls were named as Group III. PON-1 activity was determined on admission to emergency department for each group. In addition, GSs for patient groups were determined. Then, groups were compared according to their results., Results: PON-1 levels in Group I and II were significantly lower when compared to Group III. Median GSs for Group I and II were 60 and 64, respectively. The cut-off value of PON-1 for diagnosis of AMI was ≤180 U/L, which was identified by receiver characteristics receiver curve analysis. However, we could not determine a significant relationship between serum PON-1 levels and GSs in patients with AMI., Conclusion: PON-1 levels measured on admission to emergency department may be used to rule out AMI. PON-1 levels in AMI patients are found to be inefficient in determining extension of ischemia measured by GS., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objectives: Impairment of methylene tetrahydrofolate reductase (MTHFR), a key enzyme in the folate metabolism, results in an elevated plasma level of homocysteine, considered an independent risk factor for cardiovascular (CV) disease. Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with increased risk of CV death. Polymorphisms in the MTHFR gene increase the frequency of CV disease in RA. The aim of this study was to determine the expression of MTHFR gene in patients with RA, with and without ischaemic heart disease (IHD)., Methods: Relative expression of MTHFR gene and beta-actin and GAPDH as housekeeping genes was quantified by quantitative real-time polymerase chain reaction. It was analysed by the comparative Ct (threshold cycle) method in peripheral blood from 26 Spanish patients with RA (12 with IHD and 14 without IHD) and 10 healthy controls. MTHFR expression level in RA patients was also assessed according to disease activity, rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies status., Results: MTHFR expression was significantly reduced in patients with RA compared to controls (fold change = 0.85, p=0.029). It was especially true for RA patients with IHD (fold change= 0.79, p=0.021). However, no statistically significant relationship between MTHFR expression level in patients with RA and DAS28 CRP, DAS28 ESR, RF and anti-CCP status was observed., Conclusions: Patients with RA, in particular those with IHD, show a decreased expression of the MTHFR gene. This may support a potential implication of the transcriptional regulation of MTHFR in the pathogenesis of RA.

Growing evidence indicates that reactive oxygen species (ROS) may play a key role in human heart failure (HF). Monoamine oxidase (MAO) is emerging as a major ROS source in several cardiomyopathies. However, little is known about MAO activity in human failing heart and its relationship with redox imbalance. Therefore, we measured MAO activity in the left (LV) and in the right (RV) ventricle of human nonfailing (NF) and in end-stage ischemic (IHD) and nonischemic failing hearts. We found that both MAO isoforms (MAO-A/B) significantly increased in terms of activity and expression levels only in IHD ventricles. Catalase and aldehyde dehydrogenase-2 activities (ALDH-2), both implicated in MAO-catalyzed catecholamine catabolism, were significantly elevated in the failing LV, whereas, in the RV, statistical significance was observed only for ALDH-2. Oxidative stress markers levels were significantly increased only in the failing RV. Actin oxidation was significantly elevated in both failing ventricles and related to MAO-A activity and to functional parameters. These data suggest a close association between MAO-A-dependent ROS generation, actin oxidation, and ventricular dysfunction. This latter finding points to a possible pathogenic role of MAO-A in human myocardial failure supporting the idea that MAO-A could be a new therapeutic target in HF., Competing Interests: The authors declare that there are no competing interests regarding the publication of this paper.

Purpose: Calpain overexpression is implicated in aberrant angiogenesis. We hypothesized that calpain inhibition (MDL28170) would improve collateral perfusion in a swine model with hypercholesterolemia and chronic myocardial ischemia., Methods: Yorkshire swine fed a high cholesterol diet for 4 weeks underwent surgical placement of an ameroid constrictor to their left circumflex coronary artery. Three weeks later, animals received no drug, high cholesterol control group (n = 8); low-dose calpain inhibition (0.12 mg/kg; n = 9); or high-dose calpain inhibition (0.25 mg/kg; n = 8). The heart was harvested after 5 weeks., Results: Myocardial perfusion in ischemic myocardium significantly improved with high-dose calpain inhibition at rest and with demand pacing (P = .016 and .011). Endothelium-dependent microvessel relaxation was significantly improved with low-dose calpain inhibition (P = .001). There was a significant increase in capillary density, with low-dose calpain inhibition and high-dose calpain inhibition (P = .01 and .01), and arteriolar density with low-dose calpain inhibition (P = .001). Calpain inhibition significantly increased several proangiogenic proteins, including vascular endothelial growth factor (P = .02), vascular endothelial growth factor receptor 1 (P = .003), vascular endothelial growth factor receptor 2 (P = .003), and talin, a microvascular structural protein (P = .0002). There was a slight increase in proteins implicated in endothelial-dependent (nitric oxide mediated) relaxation, including extracellular signal-regulated kinase, phosphorylated extracellular signal-regulated kinase, and inducible nitric oxide synthase with calpain inhibition., Conclusions: In the setting of hypercholesterolemia, calpain inhibition improved perfusion, with a trend toward increased collateralization on angiography and increased capillary and arteriolar densities in ischemic myocardium. Calpain inhibition also improved endothelium-dependent microvessel relaxation and increased expression of proteins implicated in angiogenesis and vasodilatation., (Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Objective: To observe the effect of electroacupuncture (EA) stimulation of "Neiguan" (PC 6), etc. on expression levels of myocardial chloride (CL-) channel-related genes and intracellular protein kinase C (PKC) protein in myocardial ischemia (M) rats., Methods: Seventy SD rats were randomly divided into control group (n = 10), model group (n = 15) , Neiguan (PC 6) group (n = 15), Lieque (LU 7) group (n = 15) and non-acupoint group (n = 15). The MI model was established by i. p. of isoproterenol (ISO, a sympathomimetic beta adrenergic agonist). Electroacupuncture stimulation was applied to bilateral "Neiguan" (PC 6), "Lieque" (LU 7), or non-acupoint [the mid-point between "Tianshu" (ST 25) and "Shenque" (CV 8)] for 15 min, once a day for 7 days. Quantitative RT-PCR was employed to detect the expression levels of cystic fibrosis transmembrane conductance regulator (CFTR, a CL-channel) mRNA and chloride channel calcium-activated 1 (CLCa 1, a member of the family of calcium-activated chloride channels, CLCa) mRNA in the left cardiac ventricle tissue, and Western blot was used to detect the expression level of myocardial PKC protein of the left ventricle., Results: Compared with the control group, the expression levels of myocardial PKC protein, and CLCa 1 and CFTR genes were significantly increased in the model group (P<0.05). In comparison with the model group, the expression levels of myocardial PKC protein, and CFTR mRNA and CLCa 1 mRNA in the Neiguan group, and PKC protein and CLCa 1 mRNA in the Lieque and non-acupoint groups, as well as CFTR mRNA in the Lieque group were notably down-regulated (P<0.05). No significant change was found in the expression of CFTR mRNA in the non-acupoint group (P>0.05), and no significant differences were found between Neiguan and Lieque groups in the expression levels of PKC protein (P>0.05). The effects of "Neiguan" (PC 6) were obviously superior to those of non-acupoint in down-regulating myocardial PKC protein, CLCa 1 mRNA and CFTR mRNA (P<0.05)., Conclusion: EA stimulation of "Neiguan" (PC 6) can down-regulate the expression of myocardial PKC protein, CFTR and CLCa 1 genes in Ml rats, which may contribute to its effect in protecting rnyocardium from ischemic injury.

While ischemic preconditioning (IPC) and other cardioprotective interventions have been proposed to protect the heart from ischemia/reperfusion (I/R) injury by inhibiting mitochondrial complex I activity upon reperfusion, the exact mechanism underlying the modulation of complex I activity remains elusive. This study was aimed to test the hypothesis that IPC modulates complex I activity at reperfusion by activating mitochondrial Src tyrosine kinase, and induces cardioprotection against I/R injury. Isolated rat hearts were preconditioned by three cycles of 5-min ischemia and 5-min reperfusion prior to 30-min index ischemia followed by 2 h of reperfusion. Mitochondrial Src phosphorylation (Tyr(416)) was dramatically decreased during I/R, implying inactivation of Src tyrosine kinase by I/R. IPC increased mitochondrial Src phosphorylation upon reperfusion and this was inhibited by the selective Src tyrosine kinase inhibitor PP2. IPC's anti-infarct effect was inhibited by the selective Src tyrosine kinase inhibitor PP2. Complex I activity was significantly increased upon reperfusion, an effect that was prevented by IPC in a Src tyrosine kinase-dependent manner. In support, Src and phospho-Src were found in complex I. Furthermore, IPC prevented hypoxia/reoxygenation-induced mitochondrial reactive oxygen species (ROS) generation and cellular injury in rat cardiomyocytes, which was revoked by PP2. Finally, IPC reduced LDH release induced by both hypoxia/reoxygenation and simulated ischemia/reperfusion, an effect that was reversed by PP2 and Src siRNA. These data suggest that mitochondrial Src tyrosine kinase accounts for the inhibitory action of IPC on complex I and mitochondrial ROS generation, and thereby plays a role in the cardioprotective effect of IPC.

Background: The authors investigated the hypothesis that isoflurane modulates nitric oxide (NO) synthesis and protection against myocardial infarction through time-dependent changes in expression of key NO regulatory proteins, guanosine triphosphate cyclohydrolase (GTPCH)-1, the rate-limiting enzyme involved in the biosynthesis of tetrahydrobiopterin and endothelial nitric oxide synthase (eNOS)., Methods: Myocardial infarct size, NO production (ozone-mediated chemiluminescence), GTPCH-1, and eNOS expression (real-time reverse transcriptase polymerase chain reaction and western blotting) were measured in male Wistar rats with or without anesthetic preconditioning (APC; 1.0 minimum alveolar concentration isoflurane for 30 min) and in the presence or absence of an inhibitor of GTPCH-1, 2,4-diamino-6-hydroxypyrimidine., Results: NO2 production (158 ± 16 and 150 ± 13 pmol/mg protein at baseline in control and APC groups, respectively) was significantly (P < 0.05) increased 1.5 ± 0.1 and 1.4 ± 0.1 fold by APC (n = 4) at 60 and 90 min of reperfusion, respectively, concomitantly, with increased expression of GTPCH-1 (1.3 ± 0.3 fold; n = 5) and eNOS (1.3 ± 0.2 fold; n = 5). In contrast, total NO (NO2 and NO3) was decreased after reperfusion in control experiments. Myocardial infarct size was decreased (43 ± 2% of the area at risk for infarction; n = 6) by APC compared with control experiments (57 ± 1%; n = 6). 2, 4-Diamino-6-hydroxypyrimidine decreased total NO production at baseline (221 ± 25 and 175 ± 31 pmol/mg protein at baseline in control and APC groups, respectively), abolished isoflurane-induced increases in NO at reperfusion, and prevented reductions of myocardial infarct size by APC (60 ± 2%; n = 6)., Conclusion: APC favorably modulated a NO biosynthetic pathway by up-regulating GTPCH-1 and eNOS, and this action contributed to protection of myocardium against ischemia and reperfusion injury.

Hypoxia is known to promote vasodilation of coronary vessels through several mediators including cardiac-derived adenosine and endothelium-derived prostanoids and nitric oxide. To date, the impact of endogenous glycogen depletion in vascular smooth muscle and the resultant alterations in cellular energy state (e.g., AMP-activated protein kinase, AMPK) on the contractile response to G protein-coupled receptor agonists (e.g., serotonin, 5-HT) has not yet been studied. In the present study, ex vivo exposure of endothelium-denuded human saphenous vein rings to hypoxic and glucose-deprived conditions during KCl-induced contractions for 30 min resulted in a marked depletion of endogenous glycogen by ∼80% (from ∼1.78 μmol/g under normoxia to ∼0.36 μmol/g under hypoxia). Importantly, glycogen-depleted HSV rings, which were maintained under hypoxia/reoxygenation and glucose-deprived conditions, exhibited significant increases in basal AMPK phosphorylation (∼6-fold ↑) and 5-HT-induced AMPK phosphorylation (∼19-fold ↑) with an accompanying suppression of 5-HT-induced maximal contractile response (∼68% ↓), compared with respective controls. Exposure of glycogen-depleted HSV rings to exogenous D-glucose, but not the inactive glucose analogs, prevented the exaggerated increase in 5-HT-induced AMPK phosphorylation and restored 5-HT-induced maximal contractile response. In addition, the ability of exogenous D-glucose to rescue cellular stress and impaired contractile function occurred through GLUT1-mediated but insulin/GLUT4-independent mechanisms. Together, the present findings from clinically-relevant human saphenous vein suggest that the loss of endogenous glycogen in vascular smooth muscle and the resultant accentuation of AMPK phosphorylation by GPCR agonists may constitute a yet another mechanism of metabolic vasodilation of coronary vessels in ischemic heart disease., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The maintenance of sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) activity is crucial for cardiac function and SERCA2 is dramatically reduced in the heart exposed to hypoxic/ischemic conditions. Previous work from our group showed that hypoxia upregulates the phosphorylated form of the Ca(2+)-dependent nonreceptor protein tyrosine kinase (PTK) proline-rich tyrosine kinase 2 (pPyk2) protein levels in a low-density lipoprotein receptor-related protein (LRP1)-dependent manner. Pyk2 in turn may modulate SERCA2 in cardiomyocytes although this remains controversial. We therefore aimed to investigate the role of LRP1 on hypoxia-induced SERCA2 depletion in cardiomyocytes and to establish LRP1 signalling mechanisms involved. Western blot analysis showed that hypoxia reduced SERCA2 concomitantly with a sustained increase in LRP1 and pPyk2 protein levels in HL-1 cardiomyocytes. By impairing hypoxia-induced Pyk2 phosphorylation and HIF-1α accumulation, LRP1 deficiency prevented SERCA2 depletion and reduction of the sarcoplasmic reticulum calcium content in cardiomyocytes. Moreover, the inhibition of Pyk2 phosphorylation (with the Src-family inhibitor PP2) or the specific silencing of Pyk2 (with siRNA-anti Pyk2) preserved low HIF-1α and high SERCA2 levels in HL-1 cardiomyocytes exposed to hypoxia. We determined that the LRP1/Pyk2 axis represses SERCA2 mRNA expression via HIF-1α since HIF-1α overexpression abolished the protective effect of LRP1 deficiency on SERCA2 depletion. Our findings show a crucial role of LRP1/Pyk2/HIF-1α in hypoxia-induced cardiomyocyte SERCA2 downregulation, a pathophysiological process closely associated with heart failure., (Copyright © 2015 Elsevier Ltd. All rights reserved.)