Protecting the ischaemic and reperfused myocardium in acute myocardial infarction: distant dream or near reality?

Nicotinamide ribose ameliorates myocardial ischemia/reperfusion injury by regulating autophagy and regulating oxidative stress

Nicotinamide riboside (NR) has been reported to play a protective role in myocardial ischemia-reperfusion (I/R) injury when used in association with other drugs; however, the individual effect of NR is unknown. In the present study Evan's blue/triphenyl tetrazolium chloride staining, hematoxylin and eosin staining, echocardiography, western blotting, reverse transcription-quantitative PCR, and the detection of myocardial injury-associated markers and oxidative stress metabolites were used to explore the ability of NR to alleviate cardiac I/R injury and the relevant mechanisms of action. In a mouse model of I/R injury, dietary supplementation with NR reduced the area of myocardial ischemic infarction, alleviated pathological myocardial changes, decreased inflammatory cell infiltration and attenuated the levels of mitochondrial reactive oxygen species (ROS) and creatine kinase myocardial band (CK-MB). In addition, echocardiography suggested that NR alleviated the functional damage of the myocardium caused by I/R injury. In H9c2 cells, NR pretreatment reduced the levels of lactate dehydrogenase, CK-MB, malondialdehyde, superoxide dismutase and ROS, and reduced cell mortality after the induction of hypoxia/reoxygenation (H/R) injury. In addition, the results indicated NR activated sirt 1 via the upregulation of nicotinamide adenine dinucleotide (NAD+) and protected the cells against autophagy. The sirt 1 inhibitor EX527 significantly attenuated the ability of NR to inhibit autophagy, but had no significant effect on the ROS content of the H9c2 cells. In summary, the present study suggests that NR protects against autophagy by increasing the NAD+ content in the body via the sirt 1 pathway, although the sirt 1 pathway does not affect oxidative stress.

Pistia stratiotes has renoprotective potentials in ischemia reperfusion injury in normal and diabetic rats

OBJECTIVE

Even though oxidative and inflammatory bursts are a big part of renal reperfusion injury (RI/R), Pistia stratiotes (PS) has been used for a long time to stop these overreactions. People have said that it can drop both blood sugar and cholesterol. Hence, the goal of this study was to show how PS changed kidney reperfusion damage in both diabetic and normal rats.

MATERIALS AND METHODS

In the study, 30 min of renal ischemia (RI) was followed by 1 h of recovery for each rat. Before the test, PS (100 mg/kg p. o.) was given to the animals for 7 days. Then, using the mixture from the separated kidney tissues, the antioxidant, inflammation, and histopathological effects were determined.

RESULTS

When compared to RI/R, diabetic rats given PS had lower blood sugar, aspartate aminotransferase, blood urea nitrogen, and creatinine, myeloperoxidase, C-reactive protein, and tumor necrosis factor-alpha levels in their urine.

CONCLUSION

PS potentially worked in hyperglycemic rats protecting them against RI/R. It is possible that PS's ability to protect the kidneys of the test rats is due to its ability to fight free radicals, lower blood sugar, and stop inflammation.

A four-compound remedy AGILe protected H9c2 cardiomyocytes against oxygen glucose deprivation via targeting the TNF-α/NF-κB pathway: Implications for the therapy of myocardial infarction

Myocardial infarction (MI) is a highly prevalent and lethal disease worldwide. Prevention and timely recovery are critical for the control of the recurrence and heart failure in MI survivors. The present study was designed to investigate the cardioprotective activity of the herbal medicine formula Baoyuan Decoction (BYD) and identify the active compounds and molecular targets. The ethanolic BYD extract (BYDE) was prepared by water extraction and ethanol precipitation of four herbal medicines, Astragali Radix, Ginseng Radix et Rhizoma, Cinnamomi Cortex, and Glycyrrhizae Radix et Rhizoma. Initially, BYDE was validated for the cardioprotective effectiveness in a mouse model of ischemia injury and rat cardiomyocyte H9C2 cells. As results, BYDE effectively reduced infarct size from 56% to 37% and preserved cardiac functions in mouse MI model while protected H9C2 cells against oxygen glucose deprivation. Subsequent network pharmacology analysis revealed that 122 bioactive ingredients, including flavonoids and saponins from the UPLC-MS/MS profile of BYDE, might target 37 MI-related proteins, including inflammatory and apoptotic mediators (e.g., TNF, NFKB1, CASPs, TNFRSF1A, CXCL12, BCL2A1). Pathway enrichment analysis suggested that BYDE might control the cardiac inflammation via targeting the tumor necrosis factor-alpha (TNF-α)/nuclear factor-κB (NF-κB) pathway while the selected targets were also implicated in IL-17 signaling pathway, lipid and atherosclerosis. Consequently, adenosine, ginsenoside Rh2, isoliquiritigenin, and licochalcone A were selected to generate the four-compound mixture AGILe and validated for the inhibitory effects on the TNF-α/NF-κB pathway. The results of the present study suggested that the mixture AGILe might be a potential cardioprotective remedy against MI.

Puerarin: A protective drug against ischemia-reperfusion injury

Ischemia-reperfusion (I/R) is a pathological process that occurs in numerous organs throughout the human body and is frequently associated with severe cellular damage and death. Puerarin is an isoflavone compound extracted from the root of Pueraria lobata and has pharmacological effects such as dilating cerebral vessels and anti-free radical generation in cerebral ischemic tissues. With the deepening of experimental research and clinical research on puerarin, it has been found that puerarin has a protective effect on ischemia-reperfusion injury (IRI) of the heart, brain, spinal cord, lung, intestine and other organs. In summary, puerarin has a vast range of pharmacological effects and significant protective effects, and it also has obvious advantages in the clinical protection of patients with organ IRI. With the deepening of experimental pharmacological research and clinical research, it is expected to be an effective drug for IRI treatment. In this review, we summarize the current knowledge of the protective effect of puerarin on I/R organ injury and its possible underlying molecular mechanisms.

N(6)-methyladenosine modification: A vital role of programmed cell death in myocardial ischemia/reperfusion injury

N(6)-methyladenosine (m⁶A) modification is closely associated with myocardial ischemia/reperfusion injury (MIRI). As the most common modification among RNA modifications, the reversible m⁶A modification is processed by methylase ("writers") and demethylase ("erasers"). The biological effects of RNA modified by m⁶A are regulated under the corresponding RNA binding proteins (RBPs) ("readers"). m⁶A modification regulates the whole process of RNA, including transcription, processing, splicing, nuclear export, stability, degradation, and translation. Programmed cell death (PCD) is a regulated mechanism that maintains the internal environment's stability. PCD plays an essential role in MIRI, including apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis. However, the relationship between PCD modified with m⁶A and MIRI is still not clear. This review summarizes the regulators of m⁶A modification and their bioeffects on PCD in MIRI.

Possible effects of melatonin on reperfusion injury following coronary artery bypass graft surgery

BACKGROUND

Although coronary artery bypass graft (CABG) surgery has been reported to be one of the most effective internentions in terms of myocardial salvage, reperfusion itself can cause additional damage to the myocardium. Since there is strong evidence that free radicals are the principal offender in ischemia-reperfusion (I/R) injury, it has been suggested that treatment with antioxidant agents can be protective. Investigations have shown that melatonin secretion is partially disturbed in CABG patients. The aim of this study was to evaluate the protective effect of melatonin as an antioxidant agent on I/R injury.

METHODS

164 elective CABG candidates participated in this randomized clinical trial during the preoperative period. The candidates were randomized to receive 3 mg of melatonin tablets (physiologic dose) from 3 days before surgery until the day of discharge. Cardiac biomarkers [troponin and creatine kinase myocardial band (CKMB)] were assessed once before surgery (24 hours before surgery), and 8 and 24 hours after surgery.

RESULTS

Finally, 130 patients, 65 (50%) patients in the melatonin group and 65 (50%) in the control arm finished our study. Mean age of melatonin and control groups was 59.90 ± 9.59 and 60.80 ± 8.00 years, respectively; moreover, 47 (72.30%) in melatonin and 45 (69.23%) in control group were men. No significant difference was seen in baseline cardiac biomarkers between two groups (P > 0.05). In both groups, cardiac biomarkers (CKMB and troponin) elevated after surgery in comparison to their preoperative values. There was no statistically significant difference between the control and melatonin groups regarding the 8-hour and 24-hour troponin and CKMB when adjusted for interacting factors (P > 0.05).

CONCLUSION

Although physiological concentration of melatonin is protective against I/R injury, substitution of endogenous melatonin with the oral supplement which creates physiologic concentration may not prevent I/R injury. In order to have antioxidant effect, pharmacologic doses of melatonin should be employed.

Interplay of Oxidative Stress and Necrosis-like Cell Death in Cardiac Ischemia/Reperfusion Injury: A Focus on Necroptosis

Extensive research work has been carried out to define the exact significance and contribution of regulated necrosis-like cell death program, such as necroptosis to cardiac ischemic injury. This cell damaging process plays a critical role in the pathomechanisms of myocardial infarction (MI) and post-infarction heart failure (HF). Accordingly, it has been documented that the modulation of key molecules of the canonical signaling pathway of necroptosis, involving receptor-interacting protein kinases (RIP1 and RIP3) as well as mixed lineage kinase domain-like pseudokinase (MLKL), elicit cardioprotective effects. This is evidenced by the reduction of the MI-induced infarct size, alleviation of myocardial dysfunction, and adverse cardiac remodeling. In addition to this molecular signaling of necroptosis, the non-canonical pathway, involving Ca2+/calmodulin-dependent protein kinase II (CaMKII)-mediated regulation of mitochondrial permeability transition pore (mPTP) opening, and phosphoglycerate mutase 5 (PGAM5)–dynamin-related protein 1 (Drp-1)-induced mitochondrial fission, has recently been linked to ischemic heart injury. Since MI and HF are characterized by an imbalance between reactive oxygen species production and degradation as well as the occurrence of necroptosis in the heart, it is likely that oxidative stress (OS) may be involved in the mechanisms of this cell death program for inducing cardiac damage. In this review, therefore, several observations from different studies are presented to support this paradigm linking cardiac OS, the canonical and non-canonical pathways of necroptosis, and ischemia-induced injury. It is concluded that a multiple therapeutic approach targeting some specific changes in OS and necroptosis may be beneficial in improving the treatment of ischemic heart disease.

Actions and Therapeutic Potential of Madecassoside and Other Major Constituents of Centella asiatica: A Review

Centella asiatica is a popular herb well-known for its wide range of therapeutic effects and its use as a folk medicine for many years. Its therapeutic properties have been well correlated with the presence of asiaticoside, madecassoside, asiatic and madecassic acids, the pentacyclic triterpenes. The herb has been extensively known to treat skin conditions; nevertheless, several pre-clinical and clinical studies have scientifically demonstrated its effectiveness in other disorders. Among the active constituents that have been identified in Centella asiatica, madecassoside has been the subject of only a relatively small number of scientific reports. Therefore, this review, while including other major constituents of this plant, focuses on the therapeutic potential, pharmacokinetics and toxicity of madecassoside.

Reperfused vs. nonreperfused myocardial infarction: when to use which model

There is a lack of understanding in the cardiac remodeling field regarding the use of nonreperfused myocardial infarction (MI) and reperfused MI in animal models of MI. This Perspectives summarizes the consensus of the authors regarding how to select the optimum model for your experiments and is a part of ongoing efforts to establish rigor and reproducibility in cardiac physiology research.

Atractylenolide I alleviates ischemia/reperfusion injury by preserving mitochondrial function and inhibiting caspase-3 activity

OBJECTIVE

Myocardial ischemia/reperfusion (I/R) injury causes various severe heart diseases, including myocardial infarction. This study aimed to determine the therapeutic effect of atractylenolide I (ATR-I), which is an active ingredient isolated from Atractylodes macrocephala, on myocardial I/R injury.

METHODS

Male Sprague-Dawley rats were randomly allocated to the five following groups (nine rats/group): control, I/R, and I/R + ATR-I preconditioning (10, 50, and 250 µg). The effects of ATR-I on rats with I/R injury were verified in cardiomyocytes with hypoxia/reoxygenation. Production of reactive oxygen species was determined. The proliferative ability of cardiomyocytes was detected using the bromodeoxyuridine assay. Mitochondrial membrane potential was measured using flow cytometry. Cellular apoptosis was assessed by flow cytometry and the terminal dUTP-digoxigenin nick end labeling assay.

RESULTS

I/R and hypoxia/reoxygenation injury increased mitochondrial dysfunction and activated caspase-3 and Bax/B cell lymphoma 2 expression in vitro and in vivo. ATR-I pretreatment dose-dependently significantly attenuated myocardial apoptosis and suppressed oxidative stress as reflected by increased mitochondrial DNA copy number and superoxide dismutase activity, and decreased reactive oxygen species and Ca²⁺ content.

CONCLUSION

ATR-I protects against I/R injury by protecting mitochondrial function and inhibiting activation of caspase-3.

Protective Effect of Eichhornia Crassipes Against Cerebral Ischemia Reperfusion Injury in Normal and Diabetic rats

Eichhornia crassipes (EC) is well reported to modify inflammatory response, oxidative stress which are key pathophysiological finding of cerebral reperfusion injury, alongside it is reported to reduce cholesterol and blood glucose levels, and therefore present work was designed to investigate the effect of EC on cerebral reperfusion injury in normal and diabetic rats. Each protocol comprised cerebral ischemia (CI) for 30 min followed by reperfusion(R) for 1 h. Animals were treated with EC (100 mg/kg p.o) for seven days. At the end of the experiment, brain tissue was utilized for the measurement of oxidative stress markers, inflammatory response, infarct size and histopathological findings. EC treated rats demonstrated a significant reduction in infarct sizes when compared with CI/R and Diabetic CI/R (DCI/R) group of rats. EC treatment demonstrated a significant decreased in malondialdehyde, nitric oxide and blood glucose levels and a significant increase in the level of reduced glutathione, superoxide dismutase catalase and insulin levels, showed modification in oxidative stress. EC treatment confirmed a significant decrease in myeloperoxidase, C - reactive protein and TNF-α levels indicated a change in the inflammatory response. Histopathological findings revealed a reversal of damage in EC treated rats. EC treatmen reduced DNA fragmentation of brain tissue in treated animals. EC was found to be cerebroprotective against CI/R along with DCI/R group of rats by anti-inflammatory and antioxidant activities.

Ambra1 Alleviates Hypoxia/Reoxygenation Injury in H9C2 Cells by Regulating Autophagy and Reactive Oxygen Species

Reperfusion therapy is the most important method for treating acute myocardial infarction. However, myocardial ischemia reperfusion injury (MIRI) can offset the benefit of reperfusion therapy and worsen the outcome. In both ischemia and reperfusion, autophagy remains problematic. Activating molecule in Beclin1-regulated autophagy (Ambra1) is an important protein in autophagy regulation, and its function in MIRI remains unclear. Thus, we used H9C2 cells to investigate the function of Ambra1 in MIRI and the underlying mechanisms involved. Hypoxia and reoxygenation of H9C2 cells were used to mimic MIRI in vitro. During hypoxia, autophagy flux was blocked, then recovered in reoxygenation. Ambra1 overexpression increased autophagy in the H9C2 cells, as the LC3B II/I ratio increased, and alleviated cellular necrosis and apoptosis during hypoxia and reoxygenation. This effect was counteracted by an autophagy inhibitor. Knocking down Ambra1 can block autophagy which P62 sediment/supernatant ratio increased while the ratio of LC3B II/I decreased, and worsen outcomes. Ambra1 enhances autophagy in H9C2 cells by improving the stability and activity of the ULK1 complex. Reactive oxygen species (ROS) are an important cause of MIRI. ROS were reduced when Ambra1 was overexpressed and increased when Ambra1 was knocked down, indicating that Ambra1 can protect against hypoxia and reoxygenation injury in H9C2 cells by promoting autophagy and reducing ROS.

Diabetic animal fed with high-fat diet prevents the protective effect of myocardial ischemic preconditioning effect in isolated rat heart perfusion model

Diabetic heart (diabetes mellitus [DM]) has been shown to attenuate the beneficial effect of ischemic preconditioning (IPC) in rat heart. But the effect of IPC on diabetic rat heart that develops myopathy remains unclear. This study was designed to test the impact of IPC on diabetic cardiomyopathy (DCM) rat heart. Male Wistar rats were grouped as (a) normal, (b) DM (streptozotocin: 65 mg/kg; fed with normal diet), and (c) DCM (streptozotocin: 65 mg/kg; fed with high-fat diet). Isolated rat hearts from each group were randomly subjected to (a) normal perfusion, (b) ischemia-reperfusion (I/R), and (c) IPC procedure. At the end of the perfusion experiments, hearts were analyzed for injury, contractile function, mitochondrial activity, and oxidative stress. The results obtained from hemodynamics, cardiac injury markers, and caspase-3 activity showed that DCM rat displayed prominent I/R-associated cardiac abnormalities than DM rat heart. But the deteriorated physiological performance and cardiac injury were not recovered in both DM and DCM heart by IPC procedure. Unlike normal rat heart, IPC did not reverse mitochondrial dysfunction (determined by electron transport chain enzymes activity, ATP level, and membrane integrity, expression levels of genes like PGC-1ɑ, GSK3β, complex I, II, and V) in DCM and DM rat heart. The present study demonstrated that IPC failed to protect I/R-challenged DCM rat heart, and the underlying pathology was associated with deteriorated mitochondrial function.

The Protective Mechanism of Cannabidiol in Cardiac Injury: A Systematic Review of Non-Clinical Studies

Background:

Cardiac disease is accounted as the leading cause of worldwide morbidity and mortality. The disease is characterized by the overproduction of reactive oxygen and/or nitrogen species (ROS/RNS), and induction of oxidative stress. Cannabidiol (CBD) is a non-psychoactive ingredient of marijuana that has been reported to be safe and well tolerated in patients. Due to its pleiotropic effect, CBD has been shown to exert cytoprotective effects. This study intended to clarify the mechanisms and the potential role of CBD regarding cardiac injuries treatment.

Methods:

A systematic literature search was conducted, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, in the electronic databases including PubMed, Web of Science, Scopus, and Embase up to June 2019 using predefined search terms in the titles and abstracts. Accordingly, a set of pre-specified inclusion and exclusion criteria were considered and 8 articles were ultimately included in this study.

Results:

Our findings demonstrate that CBD has multi-functional protective assets to improve cardiac injuries; preliminary through scavenging of free radicals, and reduction of oxidative stress, apoptosis, and inflammation.

Conclusion:

CBD can protect against cardiac injuries, mainly through its antioxidative and antiapoptotic effects on the basis of non-clinical studies. The cardioprotective effects of the CBD need to be further studied in welldesigned clinical trials.

Cardioprotective Effects of Sphingosine-1-Phosphate Receptor Immunomodulator FTY720 in a Clinically Relevant Model of Cardioplegic Arrest and Cardiopulmonary Bypass

Objective: FTY720, an immunomodulator derived from sphingosine-1-phosphate, has recently demonstrated its immunomodulatory, anti-inflammatory, anti-oxidant, anti-apoptotic and anti-inflammatory properties. Furthermore, FTY720 might be a key pharmacological target for preconditioning. In this preclinical model, we have investigated the effects of FTY720 on myocardium during reperfusion in an experimental model of cardioplegic arrest (CPA) and cardiopulmonary bypass.

Methods: 30 Sprague–Dawley rats (300–350 g) were randomized into two groups: Group-A, treated with FTY720 1 mg/kg via intravenous cannulation, and Group-B, as control. After 15 min of treatment, rats underwent CPA for 30 min followed by initiation of extracorporeal life support for 2 h. Support weaning was done, and blood and myocardial tissues were collected for analysis. Hemodynamic parameters, inflammatory mediators, nitro-oxidative stress, neutrophil infiltration, immunoblotting analysis, and immunohistochemical staining were analyzed and compared between groups.

Results: FTY720 treatment activated the Akt/Erk1/2 signaling pathways, reduced the level of inflammatory mediators, activated antiapoptotic proteins, and inhibited proapoptotic proteins, leading to reduced nitro-oxidative stress and cardiomyocyte apoptosis. Moreover, significant preservation of high-energy phosphates were observed in the FTY720-treated group. This resulted in improved recovery of left ventricular systolic and diastolic functions.

Conclusion: The cardioprotective mechanism in CPA is associated with activation of prosurvival cell signaling pathways that prevents myocardial damage. FTY720 preserves high-energy phosphates attenuates myocardial inflammation and oxidative stress, and improves cardiac function.

Opioid prescription levels and postoperative outcomes in orthopedic surgery

Given the basic need for opioids in the perioperative setting, we investigated associations between opioid prescription levels and postoperative outcomes using population-based data of orthopedic surgery patients. We hypothesized that increased opioid amounts would be associated with higher risk for postoperative complications. Data were extracted from the national Premier Perspective database (2006-2013); N = 1,035,578 lower joint arthroplasties and N = 220,953 spine fusions. Multilevel multivariable logistic regression models measured associations between opioid dose prescription and postoperative outcomes, studied by quartile of dispensed opioid dose. Compared to the lowest quartile of opioid dosing, high opioid prescription was associated with significantly increased odds for deep venous thrombosis and postoperative infections by approx. 50%, while odds were increased by 23% for urinary and more than 15% for gastrointestinal and respiratory complications (P < 0.001 respectively). Furthermore, higher opioid prescription was associated with a significant increase in length of stay (LOS) and cost by 12% and 6%, P < 0.001 respectively. Cerebrovascular complications risk was decreased by 25% with higher opioid dose (P = 0.004), while odds for myocardial infarction remained unaltered. In spine cases, opioid prescription was generally higher, with stronger effects observed for increase in LOS and cost as well as gastrointestinal and urinary complications. Other outcomes were less pronounced, possibly because of smaller sample size. Overall, higher opioid prescription was associated with an increase in most postoperative complications with the strongest effect observed in thromboembolic, infectious and gastrointestinal complications, cost, and LOS. Increase in complication risk occurred stepwise, suggesting a dose-response gradient.

Lung Ischaemia-Reperfusion Injury: The Role of Reactive Oxygen Species

Lung ischaemia-reperfusion injury (LIRI) occurs in many lung diseases and during surgical procedures such as lung transplantation. The re-establishment of blood flow and oxygen delivery into the previously ischaemic lung exacerbates the ischaemic injury and leads to increased microvascular permeability and pulmonary vascular resistance as well as to vigorous activation of the immune response. These events initiate the irreversible damage of the lung with subsequent oedema formation that can result in systemic hypoxaemia and multi-organ failure. Alterations in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been suggested as crucial mediators of such responses during ischaemia-reperfusion in the lung. Among numerous potential sources of ROS/RNS within cells, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, xanthine oxidases, nitric oxide synthases and mitochondria have been investigated during LIRI. Against this background, we aim to review here the extensive literature about the ROS-mediated cellular signalling during LIRI, as well as the effectiveness of antioxidants as treatment option for LIRI.

Remote ischemic conditioning improves myocardial parameters and clinical outcomes during primary percutaneous coronary intervention: a meta-analysis of randomized controlled trials

We conducted a systematic review and meta-analysis to evaluate the effects of remote ischemic conditioning on myocardial parameters and clinical outcomes in ST segment elevation acute myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention. Ten eligible randomized controlled trials with 1006 STEMI patients were identified. Compared with controls, remote ischemic conditioning reduced the myocardial enzyme levels (standardized mean difference =-0.86; 95% CI: -1.44 to -0.28; P = 0.004; I2 = 94.5%), and increased the incidence of complete ST-segment resolution [odds ratio (OR) = 1.74; 95% CI: 1.09 to 2.77; P = 0.02; I2 = 47.9%]. Remote ischemic conditioning patients had a lower risk of all-cause mortality (OR = 0.27; 95% CI: 0.12 to 0.62; P = 0.002; I2 = 0.0%) and lower major adverse cardiovascular and cerebrovascular events rate (OR=0.45; 95% CI: 0.27 to 0.75; P = 0.002; I2 = 0.0%). Meta-analysis suggested that remote ischemic conditioning conferred cardioprotection by reducing myocardial enzymes and increasing the incidence of complete ST-segment resolution in patients after STEMI. As a result, clinical outcomes were improved in terms of mortality and incidence of major adverse cardiovascular and cerebrovascular events.

Heart and bile acids - Clinical consequences of altered bile acid metabolism

Cardiac dysfunction has an increased prevalence in diseases complicated by liver cirrhosis such as primary biliary cholangitis and primary sclerosing cholangitis. This observation has led to research into the association between abnormalities in bile acid metabolism and cardiac pathology. Approximately 50% of liver cirrhosis cases develop cirrhotic cardiomyopathy. Bile acids are directly implicated in this, causing QT interval prolongation, cardiac hypertrophy, cardiomyocyte apoptosis and abnormal haemodynamics of the heart. Elevated maternal serum bile acids in intrahepatic cholestasis of pregnancy, a disorder which causes an impaired feto-maternal bile acid gradient, have been associated with fatal fetal arrhythmias. The hydrophobicity of individual bile acids in the serum bile acid pool is of relevance, with relatively lipophilic bile acids having a more harmful effect on the heart. Ursodeoxycholic acid can reverse or protect against these detrimental cardiac effects of elevated bile acids.

Effects of simulated ischemia on the transmural differences in the Frank-Starling relationship in isolated mouse ventricular cardiomyocytes

The electrical and mechanical functions of cardiomyocytes differ in relation to the spatial locations of cells in the ventricular wall. This physiological heterogeneity may change under pathophysiological conditions, providing substrates for arrhythmia and contractile dysfunctions. Previous studies have reported distinctions in the electrophysiological and mechanical responses to ischemia of unloaded subendocardial (ENDO) and subepicardial (EPI) single cardiomyocytes. In this paper, we briefly recapitulated the available experimental data on the ischemia effects on the transmural cellular gradient in the heart ventricles and for the first time evaluated the preload-dependent changes in passive and active forces in ENDO and EPI cardiomyocytes isolated from mouse hearts subjected to simulated ischemia. Combining the results obtained in mechanically loaded contracting cardiomyocytes with data from previous studies, we showed that left ventricular ENDO and EPI cardiomyocytes are different in their mechanical responses to metabolic inhibition. Simulated ischemia showed opposite effects on the stiffness of ENDO and EPI cells and greatly prolonged the time course of contraction in EPI cells than in ENDO cells, thereby changing the normal transmural gradient in the cellular mechanics.

SUV39H1 mediated SIRT1 trans-repression contributes to cardiac ischemia-reperfusion injury

Ischemic reperfusion (I/R) contributes to deleterious cardiac remodeling and heart failure. The deacetylase SIRT1 has been shown to protect the heart from I/R injury. We examined the mechanism whereby I/R injury represses SIRT1 transcription in the myocardium. There was accumulation of trimethylated histone H3K9 on the proximal SIRT1 promoter in the myocardium in mice following I/R injury and in cultured cardiomyocytes exposed to hypoxia-reoxygenation (H/R). In accordance, the H3K9 trimethyltransferase SUV39H1 bound to the SIRT1 promoter and repressed SIRT1 transcription. SUV39H1 expression was up-regulated in the myocardium in mice following I/R insults and in H/R-treated cardiomyocytes paralleling SIRT1 down-regulation. Silencing SUV39H1 expression or suppression of SUV39H1 activity erased H3K9Me3 from the SIRT1 promoter and normalized SIRT1 levels in cardiomyocytes. Meanwhile, SUV39H1 deficiency or inhibition attenuated I/R-induced infarction and improved heart function in mice likely through influencing ROS levels in a SIRT1-dependent manner. Therefore, our data uncover a novel mechanism for SIRT1 trans-repression during cardiac I/R injury and present SUV39H1 as a druggable target for the development of therapeutic strategies against ischemic heart disease.

Cell-Penetrating Peptides: From Basic Research to Clinics

The presence of cell and tissue barriers together with the low biomembrane permeability of various therapeutics often hampers systemic drug distribution; thus, most of the available molecules are of limited therapeutic value. Opportunities to increase medicament concentrations in areas that are difficult to access now exist with the advent of cell-penetrating peptides (CPPs), which can transport into the cell a wide variety of biologically active conjugates (cargoes). Numerous preclinical evaluations with CPP-derived therapeutics have provided promising results in various disease models that, in some cases, prompted clinical trials. The outcome of these investigations has thus opened new perspectives for CPP application in the development of unprecedented human therapies that are well tolerated and directed to intracellular targets.

ATP-induced cardioprotection against myocardial ischemia/reperfusion injury is mediated through the RISK pathway

The aim of the present study was to examine the post-infarct acute effect of adenosine-5'-triphosphate (ATP) on myocardial infarction (MI) size as well as its precise molecular mechanism. Sixty New Zealand white male rabbits were exposed to 40 min of ischemia followed by 180 min of reperfusion. The rabbits were intravenously administered 3 mg/kg of ATP (ATP group) or saline (control group) immediately after reperfusion and maintained throughout the first 30 min. The wortmannin+ATP, PD-98059+ATP, and 5-hydroxydecanoic acid (5-HD) sodium salt+ATP groups were separately injected with wortmannin (0.6 mg/kg), PD-98059 (0.3 mg/kg), and 5-HD (5 mg/kg) 5 min prior to ATP administration. MI size was calculated as the percentage of the risk area in the left ventricle. Myocardial apoptosis was determined using a TUNEL assay. Western blot analysis was performed to examine the levels of protein kinase B (Akt)/p-Akt and extracellular signal-regulated kinase (ERK)/p-ERK in the ischemic myocardium, 180 min after reperfusion. The infarct size was significantly smaller in the ATP group than in the control group (p<0.05). The infarct size-reducing effect of ATP was completely blocked by wortmannin, PD-98059 and 5-HD. Compared with the control group, cardiomyocyte apoptosis was significantly reduced in the ATP group, while this did not occur in the wortmannin+ATP, PD-98059+ATP and 5-HD+ATP groups. Western blot analysis revealed a higher myocardial expression of p-Akt and p-ERK 180 min following reperfusion in the ATP versus the control group. In conclusion, cardioprotection by postischemic ATP administration is mediated through activation of the reperfusion injury salvage kinase (RISK) pathway and opening of the mitochondrial ATP-dependent potassium channels.

U0126 attenuates ischemia/reperfusion-induced apoptosis and autophagy in myocardium through MEK/ERK/EGR-1 pathway

Myocardial ischemia is one of the main causes of sudden cardiac death worldwide. Depending on the cell type and stimulus, ERK activity mediates different anti-proliferative events, such as apoptosis, autophagy, and senescence. The aim of this study was to determine the protective effect of 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio] butadiene (U0126), an ERK kinase inhibitor, on myocardial ischemia/reperfusion (I/R) injury and the mechanisms involved. An I/R model was established in vivo in C57BL/6 mice and in vitro using mouse cardiomyocytes, respectively. To evaluate the protective effects of U0126 on I/R injury, we measured the myocardial infarct area, apoptosis, and autophagy. Our data indicated that pretreatment with U0126 significantly reduced the infarct area caused by I/R. Moreover, U0126 reduced the caspase-3 activity and the number of TUNEL-positive cardiomyocytes, which together indicate decreased apoptosis. Additionally, U0126 remarkable reduced the level of Beclin-1 and LC3 and increased p62 expression, which indicates that U0126 suppressed H/R-induced autophagy. Furthermore, the relationship between U0126 and MEK/ERK pathway activation in H/R-induced cardiomyocytes was also investigated. U0126 ameliorated H/R injury through inhibition of the MEK/ERK pathway and by suppressing in the downstream EGR-1 expression. Together, our research suggests that U0126 may protect against H/R injury by preventing H/R-induced myocardium apoptosis and autophagy via the MEK/ERK/EGR-1 pathway, and may be a potential therapeutic approach for attenuating myocardial I/R injury.

Puerarin Attenuates Anoxia/Reoxygenation Injury Through Enhancing Bcl-2 Associated Athanogene 3 Expression, a Modulator of Apoptosis and Autophagy

Background

Puerarin has protective effects on ischemia-reperfusion injury, but the underlying mechanisms are not fully revealed. This study explored the effect of puerarin on the expression of Bcl-2 associated athanogene 3 (BAG3) in an in vitro model of anoxia/reoxygenation injury (A/RI) in neonate rat primary cardiomyocytes and the functions of BAG3 in A/RI.

Material/Methods

BAG3 expression in cardiomyocytes with or without puerarin pre-treatment was quantified using qRT-PCR and Western blot analysis. The effects of BAG3 on A/RI were studied by measuring the activity of lactate dehydrogenase (LDH) and creatine phosphate kinase (CPK), the concentration of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). The effects of BAG3 on autophagy and apoptosis of the cardiomyocytes after A/RI were further studied.

Results

Puerarin significantly promoted BAG3 expression in the rat primary cardiomyocytes after A/RI. Enforced BAG3 expression presented similar effects as puerarin pre-treatment in attenuating A/RI in terms of CPK, LDH, MDA, SOD, GSH-Px, ROS generation, and cell viability. BAG3 overexpression significantly stimulated autophagy in cardiomyocytes after A/RI, which presented protective effects on A/RI in terms of cell viability and apoptosis. Autophagy inhibition partly abrogated the protective effects of BAG3.

Conclusions

Puerarin can directly increase BAG3 transcription and translation in cardiomyocytes after A/RI. The elevated BAG3 expression presents protective effects on A/RI at least through enhancing autophagy and reducing apoptosis, which is a novel protective mechanism of puerarin in ARI.

Pacing Postconditioning: Recent Insights of Mechanism of Action and Probable Future Clinical Application

Ischemic heart disease, also known as coronary heart disease or coronary artery disease, accounts for >50% of cardiovascular events and is a leading cause worldwide of morbidity and mortality. Hypoperfusion of the heart is the major cause of injury in ischemic heart disease, as it results in the death of cardiomyoctes due to a lack of oxygen and energy. This injury ultimately leads to a dead area in the heart called infarcted area or myocardial infarction. The formation of myocardial infarction leads to a lengthy process of remodeling which causes many changes in the architecture and the electrophysiology of the heart. These changes may eventually lead to death due to arrhythmia or heart failure. Tremendous efforts have been made over the last decades to decrease the burden of ischemic reperfusion (I/R) injury. The first salvage to the ischemic heart is reperfusion; however, this procedure is associated with a subsequent reperfusion injury. In the 1980s, a method known as preconditioning was introduced and showed great potential in combating ischemic heart disease, but this technique is limited by the difficulty of its translation to the clinic as it requires the anticipation of an occurrence of ischemic heart disease. Not long after, a new method, postconditioning, was introduced. This method showed great success, and several studies were performed to investigate its signaling cascades and the possibility of its translation to the clinic. Thereafter, several trials were made, and many methods of postconditioning were developed. One of these is intermittent dyssynchrony, pacing postconditioning (PPC), of the heart, which involves brief episodes of electrical pacing. PPC afforded a pronounced protection to the heart against I/R injury, similar to that afforded by pre- and postconditioning.

Mitochondrial DNA oxidative damage contributes to cardiomyocyte ischemia/reperfusion-injury in rats: cardioprotective role of lycopene

Mitochondrial (mt) dysfunction and oxidative stress are involved in the pathogenesis of ischemia/reperfusion (I/R)-injury. Lycopene, a lipophilic antioxidant found mainly in tomatoes and in other vegetables and fruits, can protect mtDNA against oxidative damage. However, the role of mtDNA in myocardial I/R-injury is unclear. In the present study, we aimed to determine if and how lycopene protects cardiomyocytes from I/R-injury. In both in vitro and in vivo studies, I/R-injury increased mt 8-hydroxyguanine (8-OHdG) content, decreased mtDNA content and mtDNA transcription levels, and caused mitochondrial dysfunction in cardiomyocytes. These effects of I/R injury on cardiomycoytes were blocked by pre-treatment with lycopene. MtDNA depletion alone was sufficient to induce cardiomyocyte death. I/R-injury decreased the protein level of a key activator of mt transcription, mitochondrial transcription factor A (Tfam), which was blocked by lycopene. The protective effect of lycopene on mtDNA was associated with a reduction in mitochondrial ROS production and stabilization of Tfam. In conclusion, lycopene protects cardiomyocytes from the oxidative damage of mtDNA induced by I/R-injury.

PD150606 protects against ischemia/reperfusion injury by preventing μ-calpain-induced mitochondrial apoptosis

Calpain plays an important role in myocardial ischemia/reperfusion (I/R) injury. PD150606, a nonpeptide, cell-permeable and noncompetitive calpain inhibitor, has been shown to have protective properties in ischemic disease. The aims of the present study were to investigate whether PD150606 could alleviate myocardial I/R injury and to examine the possible mechanisms involved. The I/R model was established in vivo in C57BL/6 mice and in vitro using neonatal mouse cardiomyocytes, respectively. To evaluate the protective effects of PD150606 on I/R injury, we measured the myocardial infarct area, apoptosis, and expression of cleaved caspase-3. We also investigated the underlying mechanisms by examining mitochondrial function as reflected by the ATP concentration, translocation of cytochrome c, dynamics of mPTP opening, and membrane potential (ΔΨm), coupled with calpain activity. Pretreatment with PD150606 significantly reduced the infarct area and apoptosis caused by I/R. PD150606 pretreatment also reduced mitochondrial dysfunction by inhibiting calpain activation. Moreover, we found that μ-calpain is the main contributor to I/R-induced calpain activation. Knockdown of μ-calpain with siRNA significantly reversed calpain activation, mitochondrial dysfunction, and cardiomyocyte apoptosis caused by I/R in vitro. Our results suggest that PD150606 may protect against I/R injury via preventing μ-calpain-induced mitochondrial apoptosis.

The Protective Effect of Puerarin on Myocardial Infarction Reperfusion Injury (MIRI): A Meta-Analysis of Randomized Studies in Rat Models

Background

Although puerarin is generally considered as a protective agent for cardio-cerebrovascular diseases, the exact effect on reducing myocardial infarction reperfusion injury (MIRI) is not well understood. This study aimed to pool previous randomized controlled studies based on rat models to evaluate the effects of puerarin on MIRI.

Material/Methods

Relevant studies were searched among PubMed, Embase, Medline, and CNKI (China National Knowledge Infrastructure). To assess the therapeutic effects of protective effects of puerarin on myocardial infarction reperfusion injury, the outcome indicators which were reported in at least 3 original studies were extracted and pooled, including size of myocardial ischemia (MIS) and myocardial infarction (MIN), creatine kinase (CK), methylene dioxyamphetamine (MDA), and superoxide dismutase (SOD).

Results

Administration of puerarin could effectively reduce the size of MIN after MIR (mean difference: −29.20, 95%CI: −44.90 to −13.51, p=0.0003). Puerarin directly led to decreased CK (mean difference: −6.89, 95%CI: −9.40 to −4.38, p=0.00001) and MDA (mean difference: −2.41, 95%CI: −3.14 to −1.68, p<0.00001) and increased serum SOD (mean difference: 63.97, 95%CI: 38.19 to 89.75, p<0.00001).

Conclusions

Puerarin might have a protective effect in myocardial tissues during MIRI through increasing SOD and decreasing CK and MDA. However, more animal studies and randomized controlled clinical trials are required to confirm these results.

Deletion of CXCR4 in cardiomyocytes exacerbates cardiac dysfunction following isoproterenol administration

Altered alpha- and beta-adrenergic receptor signaling is associated with cardiac hypertrophy and failure. Stromal cell-derived factor-1α (SDF-1α) and its cognate receptor CXCR4 have been reported to mediate cardioprotection after injury through the mobilization of stem cells into injured tissue. However, little is known regarding whether SDF-1/CXCR4 induces acute protection following pathological hypertrophy and if so, by what molecular mechanism. We have previously reported that CXCR4 physically interacts with the beta-2 adrenergic receptor and modulates its down stream signaling. Here we have shown that CXCR4 expression prevents beta-adrenergic receptor induced hypertrophy. Cardiac beta-adrenergic receptors were stimulated with the implantation of a subcutaneous osmotic pump administrating isoproterenol and CXCR4 expression was selectively abrogated in cardiomyocytes using Cre-loxP-mediated gene recombination. CXCR4 knockout mice showed worsened fractional shortening and ejection fraction. CXCR4 ablation increased susceptibility to isoproterenol-induced heart failure, by upregulating apoptotic markers and reducing mitochondrial function; cardiac function decreases while fibrosis increases. Additionally, CXCR4 expression was rescued with the use of cardiotropic Adeno-associated viral-9 (AAV9) vectors. CXCR4 gene transfer reduced cardiac apoptotic signaling, improved mitochondrial function and resulted in a recovered cardiac function. Our results represent the first evidence that SDF-1/CXCR4 signaling mediates acute cardioprotection through modulating beta-adrenergic receptor signaling in vivo.

Achyranthes bidentata polypeptides reduces oxidative stress and exerts protective effects against myocardial ischemic/reperfusion injury in rats

Achyranthes bidentata, a Chinese medicinal herb, is reported to be neuroprotective. However, its role in cardioprotection remains largely unknown. Our present study aimed to investigate the effects of Achyranthes bidentata polypeptides (ABPP) preconditioning on myocardial ischemia/reperfusion (MI/R) injury and to test the possible mechanisms. Rats were treated with ABPP (10 mg/kg/d, i.p.) or saline once daily for one week. Afterward, all the animals were subjected to 30 min of myocardial ischemia followed by 4 h of reperfusion. ABPP preconditioning for one week significantly improved cardiac function following MI/R. Meanwhile, ABPP reduced infarct size, plasma creatine kinase (CK)/lactate dehydrogenase (LDH) activities and myocardial apoptosis at the end of reperfusion in rat hearts. Moreover, ABPP preconditioning significantly inhibited superoxide generation, gp91^phox expression, malonaldialdehyde formation and enhanced superoxide dismutase activity in I/R hearts. Furthermore, ABPP treatment inhibited PTEN expression and increased Akt phosphorylation in I/R rat heart. PI3K inhibitor wortmannin blocked Akt activation, and abolished ABPP-stimulated anti-oxidant effect and cardioprotection. Our study demonstrated for the first time that ABPP reduces oxidative stress and exerts cardioprotection against MI/R injury in rats. Inhibition of PTEN and activation of Akt may contribute to the anti-oxidant capacity and cardioprotection of ABPP.

AMPK-regulated and Akt-dependent enhancement of glucose uptake is essential in ischemic preconditioning-alleviated reperfusion injury

AIMS

Ischemic preconditioning (IPC) is a potent form of endogenous protection. However, IPC-induced cardioprotective effect is significantly blunted in insulin resistance-related diseases and the underlying mechanism is unclear. This study aimed to determine the role of glucose metabolism in IPC-reduced reperfusion injury.

METHODS

Normal or streptozotocin (STZ)-treated diabetic rats subjected to 2 cycles of 5 min ischemia/5 min reperfusion prior to myocardial ischemia (30 min)/reperfusion (3 h). Myocardial glucose uptake was determined by (18)F-fluorodeoxyglucose-positron emission tomography (PET) scan and gamma-counter biodistribution assay.

RESULTS

IPC exerted significant cardioprotection and markedly improved myocardial glucose uptake 1 h after reperfusion (P<0.01) as evidenced by PET images and gamma-counter biodistribution assay in ischemia/reperfused rats. Meanwhile, myocardial translocation of glucose transporter 4 (GLUT4) to plasma membrane together with myocardial Akt and AMPK phosphorylation were significantly enhanced in preconditioned hearts. Intramyocardial injection of GLUT4 siRNA markedly decreased GLUT4 expression and blocked the cardioprotection of IPC as evidence by increased myocardial infarct size. Moreover, the PI3K inhibitor wortmannin significantly inhibited activation of Akt and AMPK, reduced GLUT4 translocation, glucose uptake and ultimately, depressed IPC-induced cardioprotection. Furthermore, IPC-afforded antiapoptotic effect was markedly blunted in STZ-treated diabetic rats. Exogenous insulin supplementation significantly improved glucose uptake via co-activation of myocardial AMPK and Akt and alleviated ischemia/reperfusion injury as evidenced by reduced myocardial apoptosis and infarction size in STZ-treated rats (P<0.05).

CONCLUSIONS

The present study firstly examined the role of myocardial glucose metabolism during reperfusion in IPC using direct genetic modulation in vivo. Augmented glucose uptake via co-activation of myocardial AMPK and Akt in reperfused myocardium is essential to IPC-alleviated reperfusion injury. This intrinsic metabolic modulation and cardioprotective capacity are present in STZ-treated hearts and can be triggered by insulin.

Hydrogen sulfide in the mammalian cardiovascular system

For more than a century, hydrogen sulfide (H(2)S) has been regarded as a toxic gas. This review surveys the growing recognition of the role of H(2)S as an endogenous signaling molecule in mammals, with emphasis on its physiological and pathological pathways in the cardiovascular system. In biological fluids, H(2)S gas is a weak acid that exists as about 15% H(2)S, 85% HS(-), and a trace of S(2-). Here, we use "H(2)S" to refer to this mixture. H(2)S has been found to influence heart contractile functions and may serve as a cardioprotectant for treating ischemic heart diseases and heart failure. Alterations of the endogenous H(2)S level have been found in animal models with various pathological conditions such as myocardial ischemia, spontaneous hypertension, and hypoxic pulmonary hypertension. In the vascular system, H(2)S exerts biphasic regulation of a vascular tone with varying effects based on its concentration and in the presence of nitric oxide. Over the past decade, several H(2)S-releasing compounds (NaHS, Na(2)S, GYY4137, etc.) have been utilized to test the effect of exogenous H(2)S under different physiological and pathological situations in vivo and in vitro. H(2)S has been found to promote angiogenesis and to protect against atherosclerosis and hypertension, while excess H(2)S may promote inflammation in septic or hemorrhagic shock. H(2)S-releasing compounds and inhibitors of H(2)S synthesis hold promise in alleviating specific disease conditions. This comprehensive review covers in detail the effects of H(2)S on the cardiovascular system, especially in disease situations, and also the various underlying mechanisms.

Toll-like receptor and its roles in myocardial ischemic/reperfusion injury

The innate immune system, mediated via toll-like receptors (TLRs), represents the first line of defensive mechanisms that protects hosts from invading microbial pathogens. TLRs are a family of pattern recognition receptors (PRRs), and are pathologically activated by a set of pathogen-associated microbial patterns (PAMPs) and damage-associated molecular patterns (DAMPs). TLRs deliver signals via a specific intracellular signaling pathway involving distinctive adaptor proteins and protein kinases, and ultimately initiate transcriptional factors resulting in inflammatory responses. TLR4 is a paramount type of TLRs, located in the heart, and plays an important role in mediating myocardial ischemic reperfusion (I/R) injury. Loss-of-function experiments and animal models using genetic techniques have found that the MyD88-independent and the MyD88-dependent pathways together participate in the pathological process of myocardial I/R injury. Some other distinctive signaling pathways, such as the PI3K/AKt and AMPK/ERK pathways, interacting with the TLR4 signaling pathway, were also found to be causes of myocardial I/R injury. These different pathways activate a series of downstream transcriptional factors, produced a great quantity of inflammatory cytokines, such as IL, TNF, and initiate inflammatory response. This results in cardiac injury and dysfunction, such as myocardial stunning, no reflow phenomenon, reperfusion arrhythmias and lethal reperfusion injury, and other related complication such as ventricular remodeling. In the future, blockades aimed at blocking the signaling pathway could benefit developments in pharmacology.

The combined transduction of copper, zinc-superoxide dismutase and catalase mediated by cell-penetrating peptide, PEP-1, to protect myocardium from ischemia-reperfusion injury

Background

Our previous studies indicate that either PEP-1-superoxide dismutase 1 (SOD1) or PEP-1-catalase (CAT) fusion proteins protects myocardium from ischemia-reperfusion-induced injury in rats. The aim of this study is to explore whether combined use of PEP-1-SOD1 and PEP-1-CAT enhances their protective effects.

Methods

SOD1, PEP-1-SOD1, CAT or PEP-1-CAT fusion proteins were prepared and purified by genetic engineering. In vitro and in vivo effects of these proteins on cell apoptosis and the protection of myocardium after ischemia-reperfusion injury were measured. Embryo cardiac myocyte H9c2 cells were used for the in vitro studies. In vitro cellular injury was determined by the expression of lactate dehydrogenase (LDH). Cell apoptosis was quantitatively assessed with Annexin V and PI double staining by Flow cytometry. In vivo, rat left anterior descending coronary artery (LAD) was ligated for one hour followed by two hours of reperfusion. Hemodynamics was then measured. Myocardial infarct size was evaluated by TTC staining. Serum levels of myocardial markers, creatine kinase-MB (CK-MB) and cTnT were quantified by ELISA. Bcl-2 and Bax expression in left ventricle myocardium were analyzed by western blot.

Results

In vitro, PEP-1-SOD1 or PEP-1-CAT inhibited LDH release and apoptosis rate of H9c2 cells. Combined transduction of PEP-1-SOD1 and PEP-1-CAT, however, further reduced the LDH level and apoptosis rate. In vivo, combined usage of PEP-1-SOD1 and PEP-1-CAT produced a greater effect than individual proteins on the reduction of CK-MB, cTnT, apoptosis rate, lipoxidation end product malondialdehyde, and the infarct size of myocardium. Functionally, the combination of these two proteins further increased left ventricle systolic pressure, but decreased left ventricle end-diastolic pressure.

Conclusion

This study provided a basis for the treatment or prevention of myocardial ischemia-reperfusion injury with the combined usage of PEP-1-SOD1 and PEP-1-CAT fusion proteins.

Dyslipidemia, low left ventricular ejection fraction and high wall motion score index are predictors of progressive left ventricular dilatation after acute myocardial infarction

BACKGROUND AND OBJECTIVES

Left ventricular (LV) remodeling is a heterogeneous process, involving both infarcted and non-infarcted zones, which affects wall thickness and chamber size, shape and function.

SUBJECTS AND METHODS

A total of 758 consecutive patients (62.8±12.0 years, 539 males) with acute myocardial infarction (AMI), who were examined by echocardiography at admission and after 6 months. An increase in LV end-diastolic volume index >10% was defined as a progressive LV dilation. They were divided into two groups according to the extent of progressive LV dilatation during 6 months. Group I with progressive LV dilatation (n=154, 61.4±11.0 years, 110 males) vs. group II without LV dilatation (n=604, 64.1±12.0 years, 429 males).

RESULTS

The age and gender were no significant differences between two groups. The levels of glucose, creatinine, maximal creatine kinase (CK), CK-MB, troponin T and I were significantly increased in group I than in group II (p<0.05). Low ejection fraction (EF) and high wall motion score index (WMSI) were more common in group I than in group II (p<0.05). The presence of dyslipidemia {odds ratio (OR); 1.559, confidence interval (CI); 1.035-2.347, p=0.03}, low EF less than 45% (OR; 3.328, CI 2.099-5.276, p<0.01) and high WMSI above 1.5 (OR; 3.328, CI 2.099-5.276, p<0.01) were sig-nificant independent predictors of progressive LV dilatation by multivariate analysis.

CONCLUSION

Dyslipidemia, decreased systolic function and high WMSI were independent predictors of LV remodeling process in patients with AMI.

The synthesis of puerarin derivatives and their protective effect on the myocardial ischemia and reperfusion injury

Puerarin is a naturally occurring isoflavone and is frequently used for the treatment of cardiovascular symptoms in China. By the structural modification of the puerarin molecule at different positions, seven new puerarin derivatives were obtained, and their cardioprotective activities (in vitro and in vivo) were respectively evaluated. The finding that the activities of 3 and 8 markedly exceeded puerarin suggested that the acylated modification of phenolic hydroxyl at C-7 in the puerarin molecule may improve the cardioprotective activity, which will be an important reference for further structural optimization.

Melanocortins counteract inflammatory and apoptotic responses to prolonged myocardial ischemia/reperfusion through a vagus nerve-mediated mechanism

Recently we reported that an efferent vagal fibre-mediated cholinergic protective pathway, activated by melanocortins acting at brain melanocortin MC(3) receptors, is operative in a condition of short-term myocardial ischemia/reperfusion associated with a high incidence of severe arrhythmias and death. Here we investigated melanocortin effects, and the role of the vagus nerve-mediated cholinergic protective pathway, in a rat model of prolonged myocardial ischemia/reperfusion associated with marked inflammatory and apoptotic reactions, and a large infarct size. Ischemia was produced in rats by ligature of the left anterior descending coronary artery for 30 min. At the end of the 2-h reperfusion, western blot analysis of the inflammatory and apoptotic markers tumor necrosis factor-alpha (TNF-alpha), c-jun N-terminal kinases (JNK) and caspase-3, as well as of the anti-apoptotic extracellular signal-regulated kinases (ERK 1/2), was performed in the left ventricle. In saline-treated ischemic rats there was an increase in TNF-alpha levels and in the activity of JNK and caspase-3 accompanied, despite an appreciable ERK 1/2 activation, by a large infarct size. Intravenous treatment, during coronary artery occlusion, with the melanocortin analog [Nle(4), D-Phe(7)]alpha-melanocyte-stimulating hormone (NDP-alpha-MSH) produced a reduction in TNF-alpha levels and in the activity of JNK and caspase-3, associated with marked activation of the pro-survival kinases ERK 1/2, and consequent attenuation of infarct size. Bilateral cervical vagotomy blunted the protective effects of NDP-alpha-MSH. These results indicate that melanocortins modulate the inflammatory and apoptotic cascades triggered by prolonged myocardial ischemia/reperfusion, and reduce infarct size, seemingly by activation of the vagus nerve-mediated cholinergic protective pathway.

Effects of CXCR4 gene transfer on cardiac function after ischemia-reperfusion injury

Acute coronary occlusion is the leading cause of death in the Western world. There is an unmet need for the development of treatments to limit the extent of myocardial infarction (MI) during the acute phase of occlusion. Recently, investigators have focused on the use of a chemokine, CXCL12, the only identified ligand for CXCR4, as a new therapeutic modality to recruit stem cells to individuals suffering from MI. Here, we examined the effects of overexpression of CXCR4 by gene transfer on MI. Adenoviruses carrying the CXCR4 gene were injected into the rat heart one week before ligation of the left anterior descending coronary artery followed by 24 hours reperfusion. Cardiac function was assessed by echocardiography couple with 2,3,5-Triphenyltetrazolium chloride staining to measure MI size. In comparison with control groups, rats receiving Ad-CXCR4 displayed an increase in infarct area (13.5% +/- 4.1%) and decreased fractional shortening (38% +/- 5%). Histological analysis revealed a significant increase in CXCL12 and tumor necrosis factor-alpha expression in ischemic area of CXCR4 overexpressed hearts. CXCR4 overexpression was associated with increased influx of inflammatory cells and enhanced cardiomyocyte apoptosis in the infarcted heart. These data suggest that in our model overexpressing CXCR4 appears to enhance ischemia/reperfusion injury possibly due to enhanced recruitment of inflammatory cells, increased tumor necrosis factor-alpha production, and activation of cell death/apoptotic pathways.

Relation of the ischaemic substrate to left ventricular remodelling by cardiac magnetic resonance at 1.5 T in rabbits

OBJECTIVES

Contrast-enhanced cardiac magnetic resonance (CMR) for infarct sizing has been validated in large animals, but studies and follow-up are restricted. We sought to (1) validate CMR for assessment of myocardial area at risk (MAR) and infarct size (IS) in a rabbit model of reperfused myocardial infarction (MI); (2) analyse the relation between ischaemic substrates and subsequent left ventricular (LV) remodelling.

METHODS

Experimental reperfused acute MI was induced in 16 rabbits. Ten animals underwent cross-registered cine and contrast-enhanced CMR and histopathology at day 3 for assessment of MAR and IS (group 1). The remaining six rabbits underwent serial CMR for the study of LV remodelling (group 2).

RESULTS

In group 1, mean IS was 12.7 +/- 6.4% and 12.7 +/- 6.9% of total LV myocardial mass on CMR (late-enhancement technique) and histopathology (P = 0.52; r = 0.93). No significant difference occurred between CMR and histopathology for the calculation of MAR and IS/MAR ratio (P = 0.18 and P = 0.17), whereas correlations were strong (r = 0.92 and r = 0.95). In group 2, mean LV end-diastolic, end-systolic volumes and LV mass were significantly increased at 3 weeks compared with measurements at day 3 (P < 0.01). Significant correlations between initial IS and the increase in LV end-diastolic volume (r = 0.66) and the increase in LV mass (r = 0.48) were observed, as well as correlations between initial MAR and the increase in LV end-diastolic volume (r = 0.70) and the increase in LV mass (r = 0.37).

CONCLUSIONS

Comprehensive CMR provides accurate assessment of IS and MAR in reperfused rabbit MI. Infarct size is closely related to LV remodelling. Through the infarct size/MAR ratio, this approach has great potential for assessing interventions aimed at cardioprotection.

The cardioprotection granted by metoprolol is restricted to its administration prior to coronary reperfusion

BACKGROUND

Myocardial infarct size is a strong predictor of cardiovascular events. Intravenous metoprolol before coronary reperfusion has been shown to reduce infarct size; however, it is unknown whether oral metoprolol initiated early after reperfusion, as clinical guidelines recommend, is similarly cardioprotective. We compared the extent of myocardial salvage associated with intravenous pre-reperfusion-metoprolol administration in comparison with oral post-reperfusion-metoprolol or placebo. We also studied the effect on suspected markers of reperfusion injury.

METHODS

Thirty Yorkshire-pigs underwent a reperfused myocardial infarction, being randomized to pre-reperfusion-metoprolol, post-reperfusion-metoprolol or placebo. Cardiac magnetic resonance imaging was performed in eighteen pigs at day 3 for the quantification of salvaged myocardium. The amounts of at-risk and infarcted myocardium were quantified using T2-weighted and post-contrast delayed enhancement imaging, respectively. Twelve animals were sacrificed after 24h for reperfusion injury analysis.

RESULTS

The pre-reperfusion-metoprolol group had significantly larger salvaged myocardium than the post-reperfusion-metoprolol or the placebo groups (31 ± 4%, 13 ± 6%, and 7 ± 3% of myocardium at-risk respectively). Post-mortem analyses suggest lesser myocardial reperfusion injury in the pre-reperfusion-metoprolol in comparison with the other 2 groups (lower neutrophil infiltration, decreased myocardial apoptosis, and higher activation of the salvage-kinase phospho-Akt). Salvaged myocardium and reperfusion injury pair wise comparisons proved there were significant differences between the pre-reperfusion-metoprolol and the other 2 groups, but not among the latter two.

CONCLUSIONS

The intravenous administration of metoprolol before coronary reperfusion results in larger myocardial salvage than its oral administration initiated early after reperfusion. If confirmed in the clinical setting, the timing and route of β-blocker initiation could be revisited.