Pharmacological preconditioning with nicorandil and pioglitazone attenuates myocardial ischemia/reperfusion injury in rats. Eur J Pharmacol. 2011;663:51-58. [PMID: 21549700 DOI: 10.1016/j.ejphar.2011.04.038]

Crosstalk among Reactive Oxygen Species, Autophagy and Metabolism in Myocardial Ischemia and Reperfusion Stages

Myocardial ischemia is the most common cardiovascular disease. Reperfusion, an important myocardial ischemia tool, causes unexpected and irreversible damage to cardiomyocytes, resulting in myocardial ischemia/reperfusion (MI/R) injury. Upon stress, especially oxidative stress induced by reactive oxygen species (ROS), autophagy, which degrades the intracellular energy storage to produce metabolites that are recycled into metabolic pathways to buffer metabolic stress, is initiated during myocardial ischemia and MI/R injury. Excellent cardioprotective effects of autophagy regulators against MI and MI/R have been reported. Reversing disordered cardiac metabolism induced by ROS also exhibits cardioprotective action in patients with myocardial ischemia. Herein, we review current knowledge on the crosstalk between ROS, cardiac autophagy, and metabolism in myocardial ischemia and MI/R. Finally, we discuss the possible regulators of autophagy and metabolism that can be exploited to harness the therapeutic potential of cardiac metabolism and autophagy in the diagnosis and treatment of myocardial ischemia and MI/R.

Investigation of the active ingredients of Shuangshen Ningxin Fomula and the mechanism underlying their protective effects against myocardial ischemia-reperfusion injury by mass spectrometric imaging

BACKGROUND

Traditional Chinese medicine, particularly Shuangshen Ningxin Capsule (SSNX), has been studied intensely. SSNX includes total ginseng saponins (from Panax ginseng Meyer), total phenolic acids from Salvia miltiorrhiza Bunge, and total alkaloids from Corydalis yanhusuo W. T. Wang. It has been suggested to protect against myocardial ischemia by a mechanism that has not been fully elucidated.

METHODS

The composition and content of SSNX were determined by UHPLC-Q-TOFQ-TOF / MS. Then, a rat model of myocardial ischemia-reperfusion injury was established, and the protective effect of SSNX was measured. The protective mechanism was investigated using spatial metabolomics.

RESULTS

We found that SSNX significantly improved left ventricular function and ameliorated pathological damages in rats with myocardial ischemia-reperfusion injury. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), the protective mechanism of SSNX was examined by comparing the monomer components of drugs targeted in myocardial tissue with the distribution of myocardial energy metabolism-related molecules and phospholipids. Interestingly, some lipids display inconsistent content distribution in the myocardial ischemia risk and non-risk zones. These discrepancies reflect the degree of myocardial injury in different regions.

CONCLUSION

These findings suggest that SSNX protects against myocardial ischemia-reperfusion injury by correcting abnormal myocardial energy metabolism, changing the levels and distribution patterns of phospholipids, and stabilizing the structure of the myocardial cell membrane. MALDI-TOF MS can detect the spatial distribution of small molecule metabolites in the myocardium and can be used in pharmacological research.

Effect of the selective mitochondrial KATP channel opener nicorandil on the QT prolongation and myocardial damage induced by amitriptyline in rats

OBJECTIVES

The aim of this study is to evaluate the protective effect of nicorandil, a selective mitochondrial KATP channel opener, on QT prolongation and myocardial damage induced by amitriptyline.

METHODS

The dose of amitriptyline (intraperitoneal, i.p.) that prolong the QT interval was found 75 mg/kg. Rats were randomized into five groups the control group, amitriptyline group, nicorandil (selective mitochondrial KATP channel opener, 3 mg/kg i.p.) + amitriptyline group, 5-hdyroxydecanoate (5-HD, selective mitochondrial KATP channel blocker, 10 mg/kg i.p.) + amitriptyline group and 5-HD + nicorandil + amitriptyline group. Cardiac parameters, biochemical and histomorphological/immunohistochemical examinations were evaluated. p < 0.05 was accepted as statistically significant.

KEY FINDINGS

Amitriptyline caused statistically significant prolongation of QRS duration, QT interval and QTc interval (p < 0.05). It also caused changes in tissue oxidant (increase in malondialdehyde)/anti-oxidant (decrease in glutathione peroxidase) parameters (p < 0.05), myocardial damage and apoptosis (p < 0.01 and p < 0.001). While nicorandil administration prevented amitriptyline-induced QRS, QT, QTc prolongation (p < 0.05), myocardial damage and apoptosis (p < 0.05), it did not affect the changes in oxidative parameters (p > 0.05).

CONCLUSIONS

Our results suggest that nicorandil, a selective mitochondrial KATP channel opener, plays a protective role in amitriptyline-induced QT prolongation and myocardial damage. Mitochondrial KATP channel opening and anti-apoptotic effects may play a role in the cardioprotective effect of nicorandil.

Incidence and Severity of Acute Myocardial Injury after Thoracic Surgery: Effects of Nicorandil

Aim. To study the perioperative dynamics of myocardial injury biomarkers high-sensitivity cardiac troponin I (hs-cTnI), ischemia-modified albumin (IMA) and soluble ST2 (sST2) when taking nicorandil in lung cancer patients with concomitant coronary heart disease (CHD) undergoing surgical lung resection.

Material and methods. The study included 54 patients (11 women and 43 men) with non-small cell lung cancer and concomitant stable CHD who underwent lung resection in the volume of lobectomy or pneumonectomy. Patients were randomly assigned to the nicorandil group (oral administration 10 mg BID for 7 days before and 3 days after surgery; n=27) and the control group (n=27). In the study groups, the perioperative dynamics of hscTnI, IMA and sST2, determined in the blood before and 24 and 48h after surgery, were compared. We calculated the incidence of acute myocardial injury in the groups, which was diagnosed in cases of postoperative hs-cTnI increase of more than one 99th percentile of the upper reference limit. The associations of nicorandil intake and acute myocardial injury were evaluated.

Results. The groups were comparable in gender, age, basic clinical characteristics, as well as baseline levels of myocardial injury biomarkers. After the intervention, both samples showed an increase in the hs-cTnI and sST2 levels and a decrease in IMA concentration (all p<0.02 for related group differences). In the nicorandil group, in comparison with the control one, 48h after surgery, we found lower mean levels of hs-cTnI [16.7 (11.9;39.7) vs 44.3 (15.0;130.7) ng/l; p<0.05) and sST2 [62.8 (43.6;70.1) vs 76.5 (50.2;87.1) ng/ml; p<0.05), concentration increase rates of hs-cTnI [14.8 (0.7;42.2) vs 32.5 (14.0;125.0) ng/l; p<0.01) and sST2 [24.4 (10.3;42.4) vs 47.4 (17.5;65.3) ng/ml; p<0.05), as well as highest concentrations for the entire postoperative period of hs-cTnI [30.7 (12.0;53.7) vs 79.0 (20.3;203.3) ng/L, p<0.01] and sST2 [99.8 (73.6;162.5) vs 147.8 (87.8;207.7) ng/mL; p<0.05]. The serum IMA decreased when taking nicorandil to a greater extent [-8.0 (-12.6; -2.0) vs -2.7 (-6.0; +5.5) ng/ ml; p<0.01] 24h after surgery. Acute myocardial injury was diagnosed in 7 people in the nicorandil group (25.9%) and in 15 in the control one (55.6%; pχ2=0.027). The adjusted odds ratio of acute myocardial injury when taking nicorandil was 0.35 (95% confidence interval 0.15-0.83, p=0.017).

Conclusion. Taking  nicorandil  in patients with lung cancer and concomitant CHD  who underwent  surgical  lung resection is associated  with a lower postoperative  increase in hs-cTnI  and sST2  and a reduced risk of acute myocardial  injury, which may indicate the cardioprotective effect of nicorandil under acute surgical stress conditions.

Glutathione system enhancement for cardiac protection: pharmacological options against oxidative stress and ferroptosis

The glutathione (GSH) system is considered to be one of the most powerful endogenous antioxidant systems in the cardiovascular system due to its key contribution to detoxifying xenobiotics and scavenging overreactive oxygen species (ROS). Numerous investigations have suggested that disruption of the GSH system is a critical element in the pathogenesis of myocardial injury. Meanwhile, a newly proposed type of cell death, ferroptosis, has been demonstrated to be closely related to the GSH system, which affects the process and outcome of myocardial injury. Moreover, in facing various pathological challenges, the mammalian heart, which possesses high levels of mitochondria and weak antioxidant capacity, is susceptible to oxidant production and oxidative damage. Therefore, targeted enhancement of the GSH system along with prevention of ferroptosis in the myocardium is a promising therapeutic strategy. In this review, we first systematically describe the physiological functions and anabolism of the GSH system, as well as its effects on cardiac injury. Then, we discuss the relationship between the GSH system and ferroptosis in myocardial injury. Moreover, a comprehensive summary of the activation strategies of the GSH system is presented, where we mainly identify several promising herbal monomers, which may provide valuable guidelines for the exploration of new therapeutic approaches.

Nicorandil and Bone Marrow-derived Mesenchymal Stem Cells Therapeutic Effect after Ureteral Obstruction in Adult Male Albino Rats

BACKGROUND

Chronic kidney disease is a global health problem for which renal fibrogenesis is the final treatment target.

OBJECTIVE

In our work, we have highlighted two new strategies, nicorandil and Bone marrow-derived mesenchymal stem cells (BM-MSCs), as effective in reversing renal fibrosis induced by partial unilateral ureteral obstruction (PUUO).

METHODS

The current study included 96 male albino rats randomly divided into four groups, with 24 rats per group; Group I, the control group; Group II, PUUO, where two-thirds of the left ureter was entrenched in the psoas muscle; Group III, same surgical procedure as in Group II for 7 days, and then the rats received 15 mg/kg/day nicorandil once daily for 21 days; and Group IV, same surgical procedure as in Group II for 7 days, and then rats were given 3 × 106 of labeled MSCs injected intravenous, and left for 21 days. Blood and kidney tissues were collected for biochemical, histological, and molecular analyses.

RESULTS

Both the nicorandil and BM-MSCs treatment groups could ameliorate kidney damage evidenced by inhibition of MDA elevation and total antioxidant capacity reduction caused by PUUO. Also, there was a significant reduction observed in TNF, TGF, IL6, collagen I, and α-SMA in addition to improvement in histological examination. However, a significant difference was found between the BM-MSCs and nicorandil-treated groups.

CONCLUSION

Our results suggest that BM-MSCs and nicorandil improved renal fibrosis progression through their antiapoptotic, anti-inflammatory, and antifibrotic effects in male albino rats subjected to PUUO, with BM-MSCs being more effective compared to nicorandil.

Effects of Nicorandil Administration on Infarct Size in Patients With ST-Segment-Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: The CHANGE Trial

Background Nicorandil was reported to improve microvascular dysfunction and reduce reperfusion injury when administered before primary percutaneous coronary intervention. In this multicenter, prospective, randomized, double-blind clinical trial (CHANGE [Effects of Nicorandil Administration on Infarct Size in Patients With ST-Segment-Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention]), we investigated the effects of nicorandil administration on infarct size in patients with ST-segment-elevation myocardial infarction treated with primary percutaneous coronary intervention. Methods and Results A total of 238 patients with ST-segment-elevation myocardial infarction were randomized to receive intravenous nicorandil (n=120) or placebo (n=118) before reperfusion. Patients in the nicorandil group received a 6-mg intravenous bolus of nicorandil followed by continuous infusion at a rate of 6 mg/h. Patients in the placebo group received the same dose of placebo. The predefined primary end point was infarct size on cardiac magnetic resonance (CMR) imaging performed at 5 to 7 days and 6 months after reperfusion. CMR imaging was performed in 201 patients (84%). Infarct size on CMR imaging at 5 to 7 days after reperfusion was significantly smaller in the nicorandil group compared with the placebo (control) group (26.5±17.1 g versus 32.4±19.3 g; P=0.022), and the effect remained significant on long-term CMR imaging at 6 months after reperfusion (19.5±14.4 g versus 25.7±15.4 g; P=0.008). The incidence of no-reflow/slow-flow phenomenon during primary percutaneous coronary intervention was much lower in the nicorandil group (9.2% [11/120] versus 26.3% [31/118]; P=0.001), and thus, complete ST-segment resolution was more frequently observed in the nicorandil group (90.8% [109/120] versus 78.0% [92/118]; P=0.006). Left ventricular ejection fraction on CMR imaging was significantly higher in the nicorandil group than in the placebo group at both 5 to 7 days (47.0±10.2% versus 43.3±10.0%; P=0.011) and 6 months (50.1±9.7% versus 46.4±8.5%; P=0.009) after reperfusion. Conclusions In the present trial, administration of nicorandil before primary percutaneous coronary intervention led to improved myocardial perfusion grade, increased left ventricular ejection fraction, and reduced myocardial infarct size in patients with ST-segment-elevation myocardial infarction. Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT03445728.

Protective or Inhibitory Effect of Pharmacological Therapy on Cardiac Ischemic Preconditioning: A Literature Review

Ischemic preconditioning (IP) is an innate phenomenon, triggered by brief, non-lethal cycles of ischemia/reperfusion applied to a tissue or organ that confers tolerance to a subsequent more prolonged ischemic event. Once started, it can reduce the severity of myocardial ischemia associated with some clinical situations, such as percutaneous coronary intervention (PCI) and intermittent aortic clamping during coronary artery bypass graft surgery (CABG). Although the mechanisms underlying IP have not been completely elucidated, several studies have shown that this phenomenon involves the participation of cell triggers, intracellular signaling pathways, and end-effectors. Understanding this mechanism enables the development of preconditioning mimetic agents. It is known that a range of medications that activate the signaling cascades at different cellular levels can interfere with both the stimulation and the blockade of IP. Investigations of signaling pathways underlying ischemic conditioning have identified a number of therapeutic targets for pharmacological manipulation. This review aims to present and discuss the effects of several medications on myocardial IP.

Clinical Effect of Nicorandil Combined with Aspirin in the Treatment of Myocardial Ischemia

Objective

To investigate the clinical effect of nicorandil combined with aspirin in the treatment of myocardial ischemia.

Methods

A total of 104 patients with myocardial ischemia were admitted to our hospital from June 2019 to August 2020. These patients were selected as the research objects and randomly divided into two groups: the control group and the observation group. The control group was given asilin, and the observation group was given nicorandil tablets based on the control group. Both groups were given continuous treatment for 3 months. The curative effect, cardiac function indexes, dynamic electrocardiogram, and the occurrence of adverse reactions were observed in the two groups.

Results

The total effective rate of the observation group was 96.15% (50/52), which was higher than that of the control group (61.54%, 32/52), and the difference was statistically significant (P < 0.05). After treatment, left ventricular ejection fraction (LVEF) and peak early/late diastolic flow velocity (E/A) were increased (P < 0.05), while peak early diastolic flow velocity to peak mitral annular root movement velocity (E/Ea) was decreased (P < 0.05). After treatment, LVEF and E/A in the observation group were higher than those in the control group, while E/Ea was lower than that in the control group (P < 0.05). The frequency, duration of ST segment, and a total load of myocardial ischemia in the ST segment within 24 h after treatment were decreased compared with those before treatment (P < 0.05). The frequency and duration of ST segment decreased, and the total load of myocardial ischemia in the observation group was lower than those in the control group within 24 h after treatment (P < 0.05). After treatment, the total occurrence of adverse reactions in the observation group was lower than that in the control group (P < 0.05).

Conclusion

Nicorandil combined with aspirin in the treatment of patients with myocardial ischemia has a significant effect, which can effectively improve the electrocardiogram and cardiac function indicators of patients and reduce the incidence of adverse reactions and is worthy of clinical application.

Nicorandil alleviates cardiac remodeling and dysfunction post -infarction by up-regulating the nucleolin/autophagy axis

OBJECTIVE

The present study aimed to investigate whether the drug nicorandil can improve cardiac remodeling after myocardial infarction (MI) and the underlying mechanisms.

METHODS

Mouse MI was established by the ligation of the left anterior descending coronary artery and H9C2 cells were cultured to investigate the underlying molecular mechanisms. The degree of myocardial collagen (Col) deposition was evaluated by Masson's staining. The expressions of nucleolin, autophagy and myocardial remodeling-associated genes were measured by Western blotting, qPCR, and immunofluorescence. The apoptosis of myocardial tissue cells and H9C2 cells were detected by TUNEL staining and flow cytometry, respectively. Autophagosomes were observed by transmission electron microscopy.

RESULTS

Treatment with nicorandil mitigated left ventricular enlargement, improved the capacity of myocardial diastolic-contractility, decreased cardiomyocyte apoptosis, and inhibited myocardial fibrosis development post-MI. Nicorandil up-regulated the expression of nucleolin, promoted autophagic flux, and decreased the expressions of TGF-β1 and phosphorylated Smad2/3, while enhanced the expression of BMP-7 and phosphorylated Smad1 in myocardium. Nicorandil decreased apoptosis and promoted autophagic flux in H2O2-treated H9C2 cells. Autophagy inhibitors 3-methyladenine (3MA) and chloroquine diphosphate salt (CDS) alleviated the effects of nicorandil on apoptosis. Knockdown of nucleolin decreased the effects of nicorandil on apoptosis and nicorandil-promoted autophagic flux of cardiomyocytes treated with H2O2.

CONCLUSIONS

Treatment with nicorandil alleviated myocardial remodeling post-MI through up-regulating the expression of nucleolin, and subsequently promoting autophagy, followed by regulating TGF-β/Smad signaling pathway.

Nicorandil Inhibits Osteoclast Formation Base on NF-κB and p-38 MAPK Signaling Pathways and Relieves Ovariectomy-Induced Bone Loss

Osteolytic bone disorders are characterized by an overall reduction in bone mineral density which enhances bone ductility and vulnerability to fractures. This disorder is primarily associated with superabundant osteoclast formation and bone resorption activity. Nicorandil (NIC) is a vasodilatory anti-anginal drug with ATP-dependent potassium (KATP) channel openings. However, NIC is adopted to manage adverse cardiovascular and coronary events. Recent research has demonstrated that NIC also possesses anti-inflammatory peculiarity through the regulation of p38 MAPK and NF-κB signaling pathways. Both MAPK and NF-κB signaling pathways play pivotal roles in RANKL-induced osteoclast formation and bone resorption function. Herein, we hypothesized that NIC may exert potential biological effects against osteoclasts, and revealed that NIC dose-dependently suppressed bone marrow macrophage (BMM) precursors to differentiate into TRAP + multinucleated osteoclasts in vitro. Furthermore, osteoclast resorption assays demonstrated anti-resorptive effects exhibited by NIC. NIC had no impact on osteoblast differentiation or mineralization function. Based on Biochemical analyses, NIC relieved RANKL-induced ERK, NF-κB and p38 MAPK signaling without noticeable effects on JNK MAPK activation. However, the attenuation of NF-κB and p38 MAPK activation was sufficient to hamper the downstream induction of c-Fos and NFATc1 expression. Meanwhile, NIC administration markedly protected mice from ovariectomy (OVX)-induced bone loss through in vivo inhibition of osteoclast formation and bone resorption activity. Collectively, this work demonstrated the potential of NIC in the management of osteolytic bone disorders mediated by osteoclasts.

Protective Effect of Nicorandil on Cardiac Microvascular Injury: Role of Mitochondrial Integrity

A major shortcoming of postischemic therapy for myocardial infarction is the no-reflow phenomenon due to impaired cardiac microvascular function including microcirculatory barrier function, loss of endothelial activity, local inflammatory cell accumulation, and increased oxidative stress. Consequently, inadequate reperfusion of the microcirculation causes secondary ischemia, aggravating the myocardial reperfusion injury. ATP-sensitive potassium ion (KATP) channels regulate the coronary blood flow and protect cardiomyocytes from ischemia-reperfusion injury. Studies in animal models of myocardial ischemia-reperfusion have illustrated that the opening of mitochondrial KATP (mito-KATP) channels alleviates endothelial dysfunction and reduces myocardial necrosis. By contrast, blocking mito-KATP channels aggravates microvascular necrosis and no-reflow phenomenon following ischemia-reperfusion injury. Nicorandil, as an antianginal drug, has been used for ischemic preconditioning (IPC) due to its mito-KATP channel-opening effect, thereby limiting infarct size and subsequent severe ischemic insult. In this review, we analyze the protective actions of nicorandil against microcirculation reperfusion injury with a focus on improving mitochondrial integrity. In addition, we discuss the function of mitochondria in the pathogenesis of myocardial ischemia.

Nicorandil inhibits TLR4/MyD88/NF-κB/NLRP3 signaling pathway to reduce pyroptosis in rats with myocardial infarction

Pyroptosis is an inflammatory cell death that regulates cardiomyocyte loss after myocardial infarction. Reports indicate that nicorandil has a strong anti-inflammatory effect and protects the myocardium from myocardial infarction. However, its relationship with pyroptosis is largely unreported. Here, we investigated to influence and mechanism of action of nicorandil on cardiomyocyte pyroptosis. Forty Sprague Dawley rats were randomly assigned to sham, MI, MI + nicorandil, and MI + nicorandil + TAK242 groups (10 per group). Myocardial infarction modeling was performed through ligation of the anterior descending branch of the left coronary artery. The function of cardiac was evaluated through echocardiography, detection of myocardial adenine nucleotides, cTnI, LDH, TTC, and HE staining. Moreover, we used qRT-PCR, immunohistochemistry, and Western blotting to examine the expression of pyroptosis-related molecules and the inflammasome pathway of TLR4/MyD88/NF-κB/NLRP3. Myocardial infarction caused the activation of GSDMD, aggravated myocardial injury, and triggered cardiac dysfunction. Myocardial infarction induced pyroptotic cell death, manifested as upregulation in mRNA and protein levels associated with pyroptosis, including caspase-1 cleavage and increased expression of IL-1β and IL-18. These changes were mitigated by nicorandil. The achieved data implicate that myocardial infarction induces pyroptosis via the TLR4/MyD88/NF-κB/NLRP3 pathway, which can be inhibited by nicorandil pretreatment. Therefore, nicorandil exerts cardioprotective effects by activating K_ATP channels, and at least in part through inhibition of the TLR4/MyD88/NF-κB/NLRP3 pathway to reduce myocardial infarction-induced pyroptosis. As such, it is a potential therapy for ischemic heart disease.

Rethinking pioglitazone as a cardioprotective agent: a new perspective on an overlooked drug

Since 1985, the thiazolidinedione pioglitazone has been widely used as an insulin sensitizer drug for type 2 diabetes mellitus (T2DM). Although fluid retention was early recognized as a safety concern, data from clinical trials have not provided conclusive evidence for a benefit or a harm on cardiac function, leaving the question unanswered. We reviewed the available evidence encompassing both in vitro and in vivo studies in tissues, isolated organs, animals and humans, including the evidence generated by major clinical trials. Despite the increased risk of hospitalization for heart failure due to fluid retention, pioglitazone is consistently associated with reduced risk of myocardial infarction and ischemic stroke both in primary and secondary prevention, without any proven direct harm on the myocardium. Moreover, it reduces atherosclerosis progression, in-stent restenosis after coronary stent implantation, progression rate from persistent to permanent atrial fibrillation, and reablation rate in diabetic patients with paroxysmal atrial fibrillation after catheter ablation. In fact, human and animal studies consistently report direct beneficial effects on cardiomyocytes electrophysiology, energetic metabolism, ischemia–reperfusion injury, cardiac remodeling, neurohormonal activation, pulmonary circulation and biventricular systo-diastolic functions. The mechanisms involved may rely either on anti-remodeling properties (endothelium protective, inflammation-modulating, anti-proliferative and anti-fibrotic properties) and/or on metabolic (adipose tissue metabolism, increased HDL cholesterol) and neurohormonal (renin–angiotensin–aldosterone system, sympathetic nervous system, and adiponectin) modulation of the cardiovascular system. With appropriate prescription and titration, pioglitazone remains a useful tool in the arsenal of the clinical diabetologist.

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.

Effect of Pioglitazone on endoplasmic reticulum stress regarding in situ perfusion rat model

BACKGROUND

Ischemia-reperfusion injury (IRI) can cause insufficient microcirculation of the transplanted organ and results in a diminished and inferior graft survival rate.

OBJECTIVE

This study aimed to investigate the effect of different doses of an anti-diabetic drug, Pioglitazone (Pio), on endoplasmic reticulum stress and histopathological changes, using an in situ perfusion rat model.

METHODS

Sixty male Wistar rats were used and were divided into six groups, consisting of the control group, vehicle-treated group and four Pio-treated groups (10, 20, 30 and 40 mg/kg Pio was administered). The rats were perfused through vena cava and an outflow on the abdominal aorta occurred. Following the experiment, kidneys and livers were collected. The level of the endoplasmic reticulum stress markers (XBP1 and Caspase 12) was analyzed using Western blot and histopathological changes were evaluated.

RESULTS

Histopathological findings were correlated with the Western blot results and depict a protective effect corresponding to the elevated dosage of Pioglitazone regarding in situ perfusion rat model.

CONCLUSIONS

In our study, Pioglitazone can reduce the endoplasmic reticulum stress, and the most effective dosage proved to be the 40 mg/kg Pio referencing the kidney and liver samples.

Molecular Aspects of Volatile Anesthetic-Induced Organ Protection and Its Potential in Kidney Transplantation

Ischemia reperfusion injury (IRI) is inevitable in kidney transplantation and negatively impacts graft and patient outcome. Reperfusion takes place in the recipient and most of the injury following ischemia and reperfusion occurs during this reperfusion phase; therefore, the intra-operative period seems an attractive window of opportunity to modulate IRI and improve short- and potentially long-term graft outcome. Commonly used volatile anesthetics such as sevoflurane and isoflurane have been shown to interfere with many of the pathophysiological processes involved in the injurious cascade of IRI. Therefore, volatile anesthetic (VA) agents might be the preferred anesthetics used during the transplantation procedure. This review highlights the molecular and cellular protective points of engagement of VA shown in in vitro studies and in vivo animal experiments, and the potential translation of these results to the clinical setting of kidney transplantation.

Nicorandil inhibits cardiomyocyte apoptosis and improves cardiac function by suppressing the HtrA2/XIAP/PARP signaling after coronary microembolization in rats

Cardiomyocyte apoptosis is a key factor in the deterioration of cardiac function after coronary microembolization (CME). Nicorandil (NIC) affects myocardial injury, which may be related to the inhibition of apoptosis. However, the specific mechanism of cardioprotection has not been elucidated. Therefore, we analyzed the impact of NIC on cardiac function in rats subjected to CME and its effect on the high-temperature requirement peptidase 2/X-linked inhibitor of apoptosis protein/poly ADP-ribose polymerase (HtrA2/XIAP/PARP) pathway. Sprague Dawley rats were divided into four groups: Sham, CME, CME + NIC, and CME + UCF. Echocardiography was performed 9 hours after CME. Myocardial injury markers were evaluated in blood samples, and the heart tissue was collected for hematoxylin-eosin staining, hematoxylin basic fuchsin picric acid staining staining, TdT-mediated DUTP nick end labeling (TUNEL) staining, Western blot analysis of the HtrA2/XIAP/PARP pathway, and transmission electron microscopy. NIC ameliorated cardiac dysfunctioncaused by CME and reduced serum levels of CK-MB and LDH. In addition, NIC decreased myocardial microinfarct size and apoptotic index. NIC reduced the Bax/Bcl-2 ratio, levels of cleaved caspase 3/9, cytoplasmic HtrA2, and cleaved PARP, and increased the level of XIAP. The effects of NIC were similar to those of the HtrA2 inhibitor, UCF101. This study demonstrated that NIC reduces CME-induced myocardial injury, reduces mitochondrial damage, and improves myocardial function. The reduction in cardiomyocyte apoptosis by NIC may be mediated by the HtrA2/XIAP/PARP signaling pathway.

Effects of nicorandil on p120 expression in the spinal cord and dorsal root ganglion of rats with chronic postsurgical pain

Chronic postsurgical pain (CPSP) has a high incidence, but the underlying mechanism is not well understood. Accumulating evidence has suggested that central sensitization is the main mechanism of pain. To study the role of p120 in CPSP, a skin/muscle incision and retraction (SMIR) model was established, and immunofluorescence staining and western blotting were performed to analyze the expression of p120 in the spinal cord and dorsal root ganglion (DRG). The results demonstrated that SMIR increased the expression of p120 in the DRG and the spinal cord compared with the naive group. Furthermore, it was demonstrated that p120 was mainly distributed in the glial fibrillary acidic protein-positive astrocytes in the spinal cord, and in the neurofilament 200-positive medium and large neurons in the DRG. Our previous studies have shown that adenosine triphosphate-sensitive potassium channel (KATP) agonists can reduce postoperative pain in rats. Therefore, the changes in p120 were observed in the DRG and spinal cord of rats following the intraperitoneal injection of nicorandil, a KATP agonist. It was demonstrated that nicorandil administration could relieve mechanical pain experienced following SMIR in rats, and decrease the expression of p120 in the DRG and spinal cord. The results revealed that p120 may contribute to the prophylactic analgesic effect of nicorandil, thus providing a novel insight into the mechanism of CPSP prevention.

Nicorandil: A drug with ongoing benefits and different mechanisms in various diseased conditions

Nicorandil is a well-known antianginal agent, which has been recommended as one of the second-line treatments for chronic stable angina as justified by the European guidelines. It shows an efficacy equivalent to that of classic antianginal agents. Nicorandil has also been applied clinically in various cardiovascular diseases such as variant or unstable angina and reperfusion-induced damage following coronary angioplasty or thrombolysis. Different mechanisms have been involved in the protective effects of nicorandil in various diseases through either opening of adenosine triphosphate-sensitive potassium (KATP) channel or donation of nitric oxide (NO). The predominance or participation of any of these proposed mechanisms depends on the dose of nicorandil used, the location of diseased conditions, and if this mechanism is still functioning or not. The protection afforded by nicorandil has been shown to be mainly attributed to KATP channel opening in experimental models of myocardial and pulmonary fibrosis as well as renal injury or glomerulonephritis, whereas NO donation predominates as a mechanism of protection in hepatic fibrosis and inflammatory bowel diseases. Therefore, in different diseased conditions, it is important to know which mechanism plays the major role in nicorandil-induced curative or protective effects. This can bring new insights into the proper use of selected medication and its recommended dose for targeting certain disease.

Galanthamine improves myocardial ischemia-reperfusion-induced cardiac dysfunction, endoplasmic reticulum stress-related apoptosis, and myocardial fibrosis by suppressing AMPK/Nrf2 pathway in rats

Background

Myocardial ischemia/reperfusion (I/R) injury is an important cause of myocardial infarction and heart failure after cardiovascular surgery. Galanthamine (Gal) is an important Amaryllidaceae alkaloid with anti-acetylcholinesterase and anti-inflammatory activity. The purpose of this study was to investigate the role of Gal in myocardial I/R injury.

Methods

In this study, an animal model of myocardial I/R injury was constructed, and the rats were divided into five groups (n=10): the sham, I/R model, I/R + Gal (1 mg/kg), I/R + Gal (3 mg/kg), and I/R + Aspirin (20 mg/kg) groups. The expression of related proteins was detected by Western blotting and Immunohistochemistry, and Histological lesion was detected by HE staining.

Results

Results showed that Gal improves I/R-induced cardiac dysfunction in rats. Moreover, Gal inhibits I/R-induced endoplasmic reticulum stress (ERS)-related apoptosis by suppressing the expression of CHOP, Cleaved caspase 12, and caspase 3, and promoting the expression of CADD34 and BiP in rats. Furthermore, Gal mitigates I/R-induced myocardial fibrosis through restraining the expression of α-SMA and Collagen I in rats. Mechanically, Gal promoted the expression of AMPKα1, Nrf2 and HO-1. However, AMPK inhibitor Compound C exhibited the opposite effects. Collectively, this finding suggests that Gal improves I/R-induced cardiac dysfunction, ERS-related apoptosis, and myocardial fibrosis by activating AMPK/Nrf2 pathway in myocardial I/R rats.

Conclusions

Given this evidence, Gal may be a potential therapeutic drug for the treatment of I/R injury.

Pioglitazone protects tubular cells against hypoxia/reoxygenation injury through enhancing autophagy via AMPK-mTOR signaling pathway

Pioglitazone (Pio), a peroxisome proliferators-activated receptor-γ (PPAR-γ) agonist, may protect against renal ischemia/reperfusion injury (IRI). Recent studies have shown that autophagy plays a protective role in IRI. We aimed to evaluate whether autophagy was involved in pioglitazone-induced protection during tubular cell hypoxia/reoxygenation (H/R). Normal rat kidney proximal tubular cells NRK-52E were subjected to H/R injury, and they were divided into 6 groups: control, control + Pio, H/R, H/R + Pio, H/R + MA, H/R + MA + Pio. Autophagy-related proteins were primarily assessed by Western blot and TUNEL was performed to assess cell apoptosis. Our results showed pioglitazone pretreatment had a cytoprotective effect against H/R injury. The H/R + Pio group had an increased ratio of LC3-II to LC3-I and increased Beclin-1, decreased p62. Pioglitazone also reduced apoptosis and enhanced cell survival while inducing autophagy. Correspondingly, autophagy inhibition with 3-MA alleviated this protective effect. Furthermore, pioglitazone-induced enhancement of autophagy could be related to increased AMP-activated protein kinase (AMPK) phosphorylation and decreased Mammalian target of rapamycin (mTOR) phosphorylation. Thus, pioglitazone pretreatment protects against H/R injury by enhancting autophagy through the AMPK-mTOR signaling pathway.

Pioglitazone alleviates oxygen and glucose deprivation-induced injury by up-regulation of miR-454 in H9c2 cells

OBJECTIVES

Pioglitazone, an anti-diabetic agent, has been widely used to treat type II diabetes. However, the effect of pioglitazone on myocardial ischemia reperfusion injury (MIRI) is still unclear. Herein, the objective of this study is to learn about the regulation and mechanism of pioglitazone effects on oxygen glucose deprivation (OGD)-induced myocardial cell injury.

MATERIALS AND METHODS

A cellular injury model of OGD-treated H9c2 cells in vitro was constructed to simulate ischemic/reperfusion (I/R) injury. Then, various concentrations of pioglitazone (0, 2.5, 5, 7.5 and 10 μM) were used for the treatment of H9c2 cells, and CCK-8, flow cytometry and western blot assays were performed to examine cell viability, apoptosis, and the protein levels of factors involved in cell cycle and apoptosis in OGD-treated cells. MiR-454 inhibitor was used to suppress miR-454 expression, and whether miR-454 was involved in regulating OGD-induced cell injury was studied. Two key signal pathways were examined to uncover the underlying mechanism.

RESULTS

OGD reduced cell proliferation and induced apoptosis in H9c2 cells (P<0.05, P<0.01 or P< 0.001). OGD-induced injury was significantly attenuated by pioglitazone at the concentration of 5 μM. Additionally, pioglitazone significantly up-regulated miR-454 expression in OGD-injured cells (P< 0.05 or P< 0.01). MiR-454 suppression declined the protective effect of pioglitazone on OGD-injured H9c2 cells (P<0.05 or P< 0.01). Besides, pioglitazone activated PI3K/AKT and ERK/MAPK pathways via up-regulating miR-454.

CONCLUSION

Pioglitazone protected H9c2 cells against OGD-induced injury through up-regulating miR-454, indicating a novel therapeutic strategy for treatment of MIRI.

Pioglitazone Protects Against Renal Ischemia-Reperfusion Injury via the AMP-Activated Protein Kinase-Regulated Autophagy Pathway

Renal ischemia-reperfusion injury (IRI) is a major cause of acute renal failure. Our previous studies have shown that pioglitazone, a peroxisome proliferators-activated receptor (PPAR)-γ agonist used in type 2 diabetes, protects against renal IRI; however, the molecular mechanism underlying the renoprotective effects of pioglitazone is still unclear. In this study, we investigated the role of AMP-activated protein kinase (AMPK)-regulated autophagy in renoprotection by pioglitazone in IRI. To investigate whether pioglitazone protects renal cells from IRI, an in vivo renal IRI model was used. Cell apoptosis in the kidneys was determined by TUNEL staining. Western blotting was used to determine the expression of AMPK, autophagy-related proteins, and caspase-3/8 proteins in the kidneys. In a rat model of IRI, pioglitazone decreased the increased serum creatinine and urea nitrogen, improved renal histological score, and decreased the cell injury. Pioglitazone also increased AMPK phosphorylation, inhibited p62 and cleaved caspase-3/8 proteins, and activated autophagy-related proteins LC3 II and Beclin-1 in the kidneys of IRI rats. Moreover, GW9662, as a selective inhibitor of PPAR-γ, inhibited the protective effects of pioglitazone. These results suggest that pioglitazone exerts its protective effects in renal IRI via activation of an AMPK-regulated autophagy signaling pathway.

Role of Calcium Channel Blockers in Myocardial Preconditioning

Coronary heart disease is the leading cause of mortality and morbidity worldwide. The effects of coronary heart disease are usually attributable to the detrimental effects of acute myocardial ischaemia-reperfusion injury. Newer strategies such as ischaemic or pharmacological preconditioning have been shown to condition the myocardium to ischaemia-reperfusion injury and thus reduce the final infarct size. This review investigates the role of calcium channel blockers in myocardial preconditioning. Additionally, special attention is given to nicorandil whose mechanism of action may be associated with the cardioprotective effects of preconditioning. There are still many uncertainties in understanding the role of these agents in preconditioning, but future research in this direction will certainly help reduce coronary heart disease.

Relationship Between Glucose Fluctuations and ST-Segment Resolution in Patients With ST-Elevation Acute Myocardial Infarction

This study was conducted to assess whether any relationships exist between glucose fluctuations and electrocardiographic surrogate markers of reperfusion injury in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).We prospectively studied 63 consecutive patients with STEMI undergoing primary PCI. Patients had either diabetes (n = 30), impaired glucose tolerance (n = 26), impaired fasting glucose (n = 1), or normal glucose tolerance (n = 6). STsegment resolution (STR, %) was measured using electrocardiograms recorded 60 minutes after PCI. STR was categorized as ≥ 30% and < 30%. Glucose fluctuations were assessed by the following parameters obtained from a continuous glucose monitoring system: mean amplitude of glucose excursion (MAGE, mg/dL); and area under curve with reference to mean blood glucose (AUC_MBG, mg/ dL/day).Both MAGE and AUC_MBG were significantly higher in STR < 30%. In univariate analysis, MAGE ≥ 70 mg/dL (OR = 17.0; 95%CI, 1.93-150.12; P < 0.01), AUC_MBG ≥ 20 mg/dL/day (OR = 10.9; 95%CI, 1.92-61.77; P < 0.01), and reperfusion arrhythmias (OR = 7.6; 95%CI, 1.32-44.29; P < 0.05) were significantly associated with suboptimal STR. Multiple logistic regression analysis showed only MAGE ≥ 70 mg/dL was predictive of suboptimal STR (OR = 22.5; 95%CI, 2.43-208.66, P < 0.01).Parameters of glucose fluctuations correlated with electrocardiographic surrogate markers of impaired myocardial salvage in STEMI after reperfusion therapy. Our results suggest that glucose fluctuations may represent a potential therapeutic target to reduce myocardial reperfusion injury in STEMI.

Inhibition of 5-lipoxygenase by zileuton in a rat model of myocardial infarction

OBJECTIVE

The goal of the present study was to investigate the effects of 5-lipoxygenase (5-LOX) inhibition, alone and with cyclooxygenase (COX) inhibitors, on inflammatory parameters and apoptosis in ischemia/reperfusion (I/R)-induced myocardial damage in rats. For this purpose, zileuton, a selective and potent inhibitor of 5-LOX, resulting in suppression leukotriene production, was used.

METHODS

Male Wistar rats (200-250 g; n=12 per group) were used in the study. I/R was performed by occluding the left coronary artery for 30 minutes and 2 hours of reperfusion of the heart. Experimental groups were I/R group, sham I/R group, zileuton (5 mg/kg orally, twice daily)+I/R group, zileuton+indomethacin (5 mg/kg intraperitoneally)+I/R group, zileuton+ketorolac (10 mg/kg subcutaneously)+I/R group, and zileuton+nimesulide (5 mg/kg subcutaneously)+I/R group. Following I/R, blood samples were collected to measure tumor necrosis factor alpha (TNF-α), and left ventricles were excised for evaluation of microscopic damage; malondialdehyde (MDA), glutathione, nuclear factor (NF)-κB assays; and evaluation of apoptosis.

RESULTS

Left ventricle MDA in I/R group was higher compared to sham group; however, it did not show significant change with zileuton. Although tissue injury in I/R group was less severe in all treatment groups, it was not statistically significant. NF-κB H-score and apoptotic index, which were higher in I/R group compared to sham I/R, were decreased with application of zileuton (H-score: p<0.01; apoptotic index: p<0.001). Zileuton had no significant effect on increased serum TNF-α levels in I/R group.

CONCLUSION

5-LOX inhibition in rat myocardial infarction model attenuated increased left ventricle NF-κB expression and apoptosis and these actions were not modulated by COX inhibitors.

Epigallocatechin gallate exerts protective effects against myocardial ischemia/reperfusion injury through the PI3K/Akt pathway-mediated inhibition of apoptosis and the restoration of the autophagic flux

Epigallocatechin gallate (EGCG), a polyphenol derived from green tea, exhibits a wide range of biological activities, including antioxidant, atherosclerosis and antitumor activities. In this study, the cardioprotective effects of EGCG on myocardial ischemia/reperfusion (I/R) injury in rats and the underlying mechanisms were investigated. A rat model of I/R injury was established by ligating the left anterior descending coronary artery for 30 min, followed by reperfusion for 2 h. The levels of I/R-induced creatine kinase-MB (CK-MB) and the release of lactate dehydrogenase (LDH), as well as the infarct size, cardiomyocyte apoptosis and cardiac functional impairment were examined and compared. Western blot analysis was carried out to elucidate the potential molecular mechanisms of action of EGCG. The results revealed that EGCG post-conditioning significantly decreased the levels of CK-MB and the release of LDH, reduced the myocardial infarct size, decreased the apoptotic rate and partially preserved heart function. Furthermore, EGCG decreased the expression of cleaved caspase-3 concomitantly with the upregulation of PI3K, and the phosphorylation of Akt and endothelial nitric oxide synthase (eNOS). It also inhibited I/R-induced overautophagy and promoted the clearance of autophagosomes, as evidenced by a decrease in the ratio of microtubule-associated protein 1 light chain 3 (LC3)-II/LC3-I, the downregulation of Beclin1, Atg5 and p62, and the upregulation of active cathepsin D. Additionally, we observed an increase in the phosphorylation levels of the mammalian target of rapamycin (mTOR) following treatment with EGCG. Taken together, the findings of this study demonstrate that, EGCG post-conditioning alleviates myocardial I/R injury by inhibiting apoptosis and restoring the autophagic flux, which is associated with several targets of the PI3K/Akt signaling pathway.

Nicorandil enhances the efficacy of mesenchymal stem cell therapy in isoproterenol-induced heart failure in rats

Stem cell transplantation has emerged as a promising technique for regenerative medicine in cardiovascular therapeutics. However, the results have been less than optimal. The aim of the present study was to investigate whether nicorandil could offer an additional benefit over bone marrow-derived mesenchymal stem cell therapy in isoproterenol-induced myocardial damage and its progression to heart failure in rats. Isoproterenol was injected subcutaneously for 2 consecutive days at doses of 85 and 170 mg/kg/day, respectively. Nicorandil (3 mg/kg/day) was then given orally with or without a single intravenous bone marrow-derived mesenchymal stem cell administration. Electrocardiography and echocardiography were recorded 2 weeks after the beginning of treatment. Rats were then sacrificed and the ventricle was isolated for estimation of tumor necrosis factor-alpha, vascular endothelial growth factor and transforming growth factor-beta. Moreover, protein expressions of caspase-3, connexin-43 as well as endothelial and inducible nitric oxide synthases were evaluated. Finally, histological studies of myocardial fibrosis and blood vessel density were performed and cryosections were done for estimation cell homing. Combined nicorandil/bone marrow-derived mesenchymal stem cell therapy provided an additional improvement compared to cell therapy alone toward reducing isoproterenol-induced cardiac hypertrophy, fibrosis and inflammation. Notably, combined therapy induced significant increase in angiogenesis and cell homing and prevented isoproterenol-induced changes in contractility and apoptotic markers. In conclusion, combined nicorandil/bone marrow-derived mesenchymal stem cell therapy was superior to cell therapy alone toward preventing isoproterenol-induced heart failure in rats through creation of a supportive environment for mesenchymal stem cells.

Molecular Characterization of Reactive Oxygen Species in Myocardial Ischemia-Reperfusion Injury

Myocardial ischemia-reperfusion (I/R) injury is experienced by individuals suffering from cardiovascular diseases such as coronary heart diseases and subsequently undergoing reperfusion treatments in order to manage the conditions. The occlusion of blood flow to the tissue, termed ischemia, can be especially detrimental to the heart due to its high energy demand. Several cellular alterations have been observed upon the onset of ischemia. The danger created by cardiac ischemia is somewhat paradoxical in that a return of blood to the tissue can result in further damage. Reactive oxygen species (ROS) have been studied intensively to reveal their role in myocardial I/R injury. Under normal conditions, ROS function as a mediator in many cell signaling pathways. However, stressful environments significantly induce the generation of ROS which causes the level to exceed body's antioxidant defense system. Such altered redox homeostasis is implicated in myocardial I/R injury. Despite the detrimental effects from ROS, low levels of ROS have been shown to exert a protective effect in the ischemic preconditioning. In this review, we will summarize the detrimental role of ROS in myocardial I/R injury, the protective mechanism induced by ROS, and potential treatments for ROS-related myocardial injury.

Role of Trimetazidine in Ischemic Preconditioning in Patients With Symptomatic Coronary Artery Disease

Ischemic preconditioning (IP) is a powerful cardioprotective cellular mechanism that has been related to the "warm-up phenomenon" or "walk-through" angina, and has been documented through the use of sequential exercise tests (ETs). It is known that several drugs, for example, cromokalim, pinacidil, adenosine, and nicorandil, can interfere with the cellular pathways of IP. The purpose of this article is to report the effect of the anti-ischemic agent trimetazidine (TMZ) on IP in symptomatic coronary artery disease (CAD) patients.We conducted a prospective study evaluating IP by the analysis of ischemic parameters in 2 sequential ETs. In phase I, without TMZ, patients underwent ET1 and ET2 with a 30-minute interval between them. In phase II, after 1 week of TMZ 35 mg twice daily, all patients underwent 2 consecutive ETs (ET3 and ET4). IP was considered present when the time to 1.0-mm segment ST on electrocardiogram deviation (T-1.0 mm) and rate pressure product (RPP) were greater in the second of 2 tests. The improvement in T-1.0 mm and RPP were compared in the 2 phases: without TMZ and after 1-week TMZ to assess the action of such drug in myocardial protective mechanisms. ETs were analyzed by 2 independent cardiologists.From 135 CAD patients screened, 96 met inclusion criteria and 62 completed the study protocol. Forty patients manifested IP by demonstrating an improvement in T-1.0 mm in ET2 compared with ET1, without the use of any drugs (phase I). In phase II, after 1-week TMZ, 26 patients (65%) did not show any incremental result in ischemic parameters in ET4 compared with ET3. Furthermore, of these patients, 8 (20%) had IP blockage.In this study, TMZ did not add any benefit to IP in patients with stable symptomatic CAD.

Fargesin as a potential β₁ adrenergic receptor antagonist protects the hearts against ischemia/reperfusion injury in rats via attenuating oxidative stress and apoptosis

Fargesin displayed similar chromatographic retention peak to metoprolol in the cardiac muscle/cell membrane chromatography (CM/CMC) and β1 adrenergic receptor/cell membrane chromatography (β1AR/CMC) models. To provide more biological information about fargesin, we investigated the effects of fargesin on isoproterenol-(ISO-) induced cells injury in the high expression β1 adrenergic receptor/Chinese hamster ovary-S (β1AR/CHO-S) cells and occluding the left coronary artery- (LAD-) induced myocardial ischemia/reperfusion (MI/R) injury in rats. The results in vitro showed that ISO-induced canonical cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) levels were decreased by fargesin in β1AR/CHO-S cells. Fargesin attenuated the serum creatine kinase (CK), lactate dehydrogenase (LDH), and improved histopathological changes of ischemic myocardium compared with the I/R rats. Similar results were obtained with Evans Blue/TTC staining, in which fargesin notably reduced infarct size. Moreover, compared with the I/R group, fargesin increased COX release and the activities of some endogenous antioxidative enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), but suppressed malondialdehyde (MDA), and intracellular ROS release. Additionally, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay demonstrated fargesin suppressed myocardial apoptosis, which may be related to inhibition of caspase-3 activity. Taken together, these results provided substantial evidences that fargesin as a potential β1AR antagonist through cAMP/PKA pathway could protect against myocardial ischemia/reperfusion injury in rats. The underlining mechanism may be related to inhibiting oxidative stress and myocardial apoptosis.

Protective effects of crocetin pretreatment on myocardial injury in an ischemia/reperfusion rat model

Crocetin is one of the major active constituents of saffron extract, and it is a carotenoid compound that prevents reactive oxygen species and has anti-inflammation and anti-apoptosis characteristics. This study aims to investigate whether crocetin repairs myocardial damage in vivo after ischemia reperfusion (I/R) and the mechanisms underlying its cardioprotective effects. Male Wistar rats were randomly allocated into three groups: Sham, I/R, CRO. Crocetin (50mg/kg/day, i.g.) or sodium carboxymethylcellulose (CMC-Na) was intragastrically administered to Wistar rats for 7 days before operation. Myocardial ischemia reperfusion injury (MIRI) was induced by occluding the left anterior descending (LAD) coronary artery for 45min and subsequent reperfusion for 3h. The cardioprotective effects of crocetin were evaluated by biochemical values, histopathological observations and the antiapoptotic relative proteins and gene expressions. In the rat model, pretreatment with 50mg/kg crocetin reduced the cardiac injury, oxidative stress and inflammation compared with that of the non-treated rats, as shown by the decreased levels of infarct size, creatine kinase-MB (CK-MB), malondialdehyde (MDA), and tumor necrosis factor-alpha (TNF-α) activity and the increased levels of total superoxide dismutase (T-SOD) and inflammation cytokines interleukin-10 (IL-10) activity. Crocetin activation also decreases the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining positive percentage and Bax expression, elevated Bcl-2 and endothelial nitric oxide synthase (eNOS) expression and nitrite (NO) production, these indicating that crocetin can suppress the apoptosis damage. These results indicate that crocetin can provide protection against MIRI in rats by inhibiting ROS production, blocking inflammation, and reducing myocardium apoptosis.

Impact of hypoglycemic agents on myocardial ischemic preconditioning

Murry et al in 1986 discovered the intrinsic mechanism of profound protection called ischemic preconditioning. The complex cellular signaling cascades underlying this phenomenon remain controversial and are only partially understood. However, evidence suggests that adenosine, released during the initial ischemic insult, activates a variety of G protein-coupled agonists, such as opioids, bradykinin, and catecholamines, resulting in the activation of protein kinases, especially protein kinase C (PKC). This leads to the translocation of PKC from the cytoplasm to the sarcolemma, where it stimulates the opening of the ATP-sensitive K⁺ channel, which confers resistance to ischemia. It is known that a range of different hypoglycemic agents that activate the same signaling cascades at various cellular levels can interfere with protection from ischemic preconditioning. This review examines the effects of several hypoglycemic agents on myocardial ischemic preconditioning in animal studies and clinical trials.

Nicorandil protects against ischaemia-reperfusion injury in newborn rat kidney

Ischaemia-reperfusion injury (IRI) is the predominant cause of acute kidney injury. Nevertheless, the underlying molecular mechanisms are still unclear. The current study investigated the effects of nicorandil on ATP-sensitive potassium (KATP) channels and the potential signal transduction pathway(s) in a rat kidney IRI model and in cultured tubular HK-2 cells subjected to oxygen and glucose deprivation/reoxygenation (OGD/R) injury. The standard procedure for IRI was performed in newborn rat kidneys. Pretreatment with nicorandil (10 mg/kg) 2 h prior to induction of IRI improved renal function, attenuated tubule damage, and prevented apoptosis of tubule cells, infiltration of neutrophils and macrophages, and production of inflammatory cytokines interleukin (IL)-6, IL-17 and tumour necrosis factor-α. Ischaemia-reperfusion-induced reduction of KIR6.2 was restored to normal levels by nicorandil. The activation of the phosphoinositide-3-kinase (PI3K)-Akt-nuclear factor (NF)-κB axis was detected in this rat kidney IRI model, which was blocked by nicorandil. The renoprotection of nicorandil against IRI was abolished by its inhibitor glibenclamide (1 mg/kg). Similar results were obtained in OGD/R-damaged HK-2 cells. Taken together, our findings demonstrated the specific renoprotective role of nicorandil in the newborn rat IRI kidney by decreasing the production of inflammatory cytokines, and restoring the expression of KIR6.2 potentially through the PI3K-Akt-NF-κB axis.

Effect of aqueous extract of sanweitanxiang powder on calcium homeostasis protein expression in ischemic-reperfusion injury rat heart

OBJECTIVE

To investigate the underlying mechanism of reduced myocardial ischemia-reperfusion (I/R) injury in rats using the traditional Tibetan medicine Sanweitanxiang powder (SWTX).

METHODS

Rats were randomly divided into six groups (n = 10) as follows: (a) propranolol dinitrate control group, given propranolol dinitrate 0.02 g/kg for 10 days before I/R, (b) SWTX with a high dose group, given SWTX 1.5 g/kg for 10 days before I/R, (c) SWTX with a medium dose group, given SWTX 1.25 g/kg for 10 days before I/R, (d) sham group (Sham), in which the rat heart was exposed by pericardiotomy but without I/R, (e) SWTX with a low dose group, given SWTX 1.0 g/kg for 10 days before I/R, and (f) I/R injury group. Rats were intragastrically pretreated with propranolol dinitrate or SWTX. After that, the operation to cause ischemia and reperfusion was conducted. The histopathologic changes of rat hearts were observed by hematoxylin and eosin staining and transmission electron microscopy. Ca2+ homeostasis protein expression was determined by western blot.

RESULTS

After SWTX pretreatment, the development of ultrastructural pathological changes from IR injury was attenuated. A decrease in the expression of B-cell lymphoma 2 associated X protein, and an increase in the expression of B-cell lymphoma 2 were observed. An increased activation of extracellular signal regulated kinases were found. Compared with the sham group, the expression of sarcoplasmic reticulum calcium-ATPase, phospholamban, and calsequestrin were all up-regulated after pretreatment with SWTX.

CONCLUSION

The protective mechanism of SWTX pretreatment on myocardial I/R injury might be related to its effect on maintaining the balance of calcium homeostasis in rat heart.

Nicorandil ameliorates mitochondrial dysfunction in doxorubicin-induced heart failure in rats: possible mechanism of cardioprotection

Despite of its known cardiotoxicity, doxorubicin is still a highly effective anti-neoplastic agent in the treatment of several cancers. In the present study, the cardioprotective effect of nicorandil was investigated on hemodynamic alterations and mitochondrial dysfunction induced by cumulative administration of doxorubicin in rats. Doxorubicin was injected i.p. over 2 weeks to obtain a cumulative dose of 18 mg/kg. Nicorandil (3 mg/kg/day) was given orally with or without doxorubicin treatment. Heart rate and aortic blood flow were recorded 24 h after receiving the last dose of doxorubicin. Rats were then sacrificed and hearts were rapidly excised for estimation of caspase-3 activity, phosphocreatine and adenine nucleotides contents in addition to cytochrome c, Bcl2, Bax and caspase 3 expression. Moreover, mitochondrial oxidative phosphorylation capacity, creatine kinase activity and oxidative stress markers were measured together with the examination of DNA fragmentation and ultrastructural changes. Nicorandil was effective in alleviating the decrement of heart rate and aortic blood flow and the state of mitochondrial oxidative stress induced by doxorubicin cardiotoxicity. Nicorandil also preserved phosphocreatine and adenine nucleotides contents by restoring mitochondrial oxidative phosphorylation capacity and creatine kinase activity. Moreover, nicorandil provided a significant cardioprotection via inhibition of apoptotic signaling pathway, DNA fragmentation and mitochondrial ultrastructural changes. Interestingly, nicorandil did not interfere with cytotoxic effect of doxorubicin against the growth of solid Ehrlich carcinoma. In conclusion, nicorandil was effective against the development of doxorubicin-induced heart failure in rats as indicated by improvement of hemodynamic perturbations, mitochondrial dysfunction and ultrastructural changes without affecting its antitumor activity.

Protective role of deoxyschizandrin and schisantherin A against myocardial ischemia-reperfusion injury in rats

Background

Our previous studies suggested that deoxyschizandrin (DSD) and schisantherin A (STA) may have cardioprotective effects, but information in this regard is lacking. Therefore, we explored the protective role of DSD and STA in myocardial ischemia–reperfusion (I/R) injury.

Methodology/Principal Findings

Anesthetized male rats were treated once with DSD and STA (each 40 µmol/kg) through the tail vein after 45 min of ischemia, followed by 2-h reperfusion. Cardiac function, infarct size, biochemical markers, histopathology and apoptosis were measured and mRNA expression of gp91^phox in myocardial tissue assessed by RT-PCR. Neonatal rat cardiomyocytes were pretreated with DSD and STA and then damaged by H₂O₂. Cell apoptosis was tested by a flow cytometric assay. Compared with the I/R group: (i) DSD and STA could significantly reduce the abnormalities of LVSP, LVEDP, ±dp/dt_max and arrhythmias, thereby showing their protective roles in cardiac function; (ii) DSD and STA could significantly attenuate the infarct size and MDA release while increasing SOD activity, suggesting a role in reducing myocardial injury; (iii) tissue morphology and myocardial textual analysis revealed that DSD and STA mitigated changes in myocardial histopathology; (iv) DSD and STA decreased apoptosis (33.56±2.58% to 10.28±2.80% and 10.98±1.99%, respectively) and caspase-3 activity in the myocardium (0.62±0.02 OD/mg to 0.38±0.02 OD/mg and 0.32±0.02 OD/mg, respectively), showing their protective effects upon cardiomyocytes; and (v) DSD and STA had similar protective effects on I/R injury as those seen with the positive control metoprolol. In vitro, DSD and STA could significantly decrease the apoptosis of neonatal cardiomyocytes.

Conclusions/Significance

These data suggest that DSD and STA can protect against myocardial I/R injury. The underlining mechanism may be related to their role in inhibiting cardiomyocyte apoptosis.

Pioglitazone protects against renal ischemia-reperfusion injury by enhancing antioxidant capacity

BACKGROUND

In our previous study, we showed that pioglitazone exerts protective effects on renal ischemia-reperfusion injury (IRI) in mice by abrogating renal cell apoptosis. Oxidative stress due to excessive production of reactive oxygen species and subsequent lipid peroxidation plays a critical role in renal IRI. The purpose of the current study is to demonstrate the effect of pioglitazone on renal IRI by modulation of oxidative stress.

MATERIALS AND METHODS

IRI was induced by bilateral renal ischemia for 45 min followed by reperfusion. Thirty healthy male Balb/c mice were randomly assigned to one of the following groups: phosphate buffer solution (PBS) + IRI, pioglitazone + IRI, PBS + sham IRI, pioglitazone + sham IRI. Kidney function tests and kidney antioxidant activities were determined 24 h after reperfusion.

RESULTS

Pretreatment with pioglitazone produced reduction in serum levels of blood urea nitrogen and creatinine caused by IRI. Pretreatment with pioglitazone before IRI resulted in a higher level of kidney enzymatic activities of superoxide dismutase, glutathione, catalase, and total antioxidant capacity than in the PBS-pretreated IRI group.

CONCLUSIONS

Our results indicate that pioglitazone can provide protection for kidneys against IRI by enhancing antioxidant capacity. Therefore, pioglitazone could be a potential therapeutic approach to prevent renal IRI relevant to various clinical conditions.

Evaluation of the effects of nicorandil and its molecular precursor (without radical NO) on proliferation and apoptosis of 786-cell

Nicorandil is a nitric oxide (NO) donor used in the treatment of angina symptoms. It has also been reported to protect cells and affect the proliferation and death of cells in some tissues. The molecules that interfere with these processes can cause dysfunction in healthy tissues but can also assist in the therapy of some disorders. In this study we examined the effect of nicorandil and of the molecular precursor that does not have the NO radical (N-(beta-hydroxyethyl) nicotinamide) on the cell proliferation and death of human renal carcinoma cells (786-O) under normal oxygenation conditions. The molecular precursor was used in order to analyze the effects independents of NO. In the cytotoxicity test, nicorandil was shown to be cytotoxic at very high concentrations and it was more cytotoxic than its precursor (cytotoxic at concentrations of 2,000 and 3,000 μg/mL, respectively). We propose that the lower cytotoxicity of the precursor is due to the absence of the NO radical. In this study, the cells exposed to nicorandil showed neither statistically significant changes in cell proliferation nor increases in apoptosis or genotoxicity. The precursor generated similar results to those of nicorandil. We conclude that nicorandil causes no changes in the proliferation or apoptosis of the cell 786-O in normal oxygenation conditions. Moreover, the lack of NO radical in the precursor molecule did not show a different result, except in the cell cytotoxicity.

Protective effects of pioglitazone on renal ischemia-reperfusion injury in mice

BACKGROUND

Renal ischemia-reperfusion injury (IRI) is a complex pathophysiologic process involving cell apoptosis and oxidant damages that leads to acute renal failure in both native kidneys and renal allografts. Pioglitazone is a novel class of oral antidiabetic agents currently used to treat type 2 diabetes mellitus. Pioglitazone exerts protective effects on acute myocardial ischemia and acute cerebral ischemia. The aim of this study was to investigate the possible beneficial effects of pioglitazone on renal IRI in mice.

METHODS

IRI was induced by bilateral renal ischemia for 45 min followed by reperfusion. Fifty-five healthy male Balb/c mice were randomly assigned to one of the following groups: PBS + IRI, pioglitazone + IRI, PBS + sham IRI, pioglitazone + sham IRI. Kidney function tests, histopathologic examination, renal cell Bcl-2, and Bax expression were determined 24 h after reperfusion. Animals' survival was examined 7 days after operation.

RESULTS

Animals pretreated with pioglitazone had lower plasma levels of blood urea nitrogen and creatinine caused by IRI, lower histopathologic scores, and improved survival rates following IRI. Renal cell apoptosis induced by IRI was abrogated in kidneys of mice pretreated by pioglitazone, with an increase in Bcl-2 expression and a decrease in Bax expression. Furthermore, pioglitazone pretreatment protected against lethal renal IRI.

CONCLUSIONS

Peroxisome proliferator-activated receptor activation by pioglitazone exerts protective effects on renal IRI in mice by abrogating renal cell apoptosis. Thus, pioglitazone could be a novel therapeutic tool in renal IRI.