Apoptosis In Ischemia-reperfusion Injury Research Articles

C-Jun N-terminal Kinase Supports Autophagy in Testicular Ischemia but Triggers Apoptosis in Ischemia-Reperfusion Injury.

Oxidative stress triggered by testicular torsion and detorsion in young males could negatively impact future fertility. Using a rat animal model for testicular IRI (tIRI), we aim to study the induction of autophagy (ATG) during testicular ischemia and tIRI and the role of oxidative-stress-induced c-Jun N-terminal Kinase (JNK) as a cytoprotective mechanism. Sixty male Sprague-Dawley rats were divided into five groups: sham, ischemia only, ischemia+SP600125 (a JNK inhibitor), tIRI only, and tIRI+SP600125. The tIRI rats underwent an ischemic injury for 1 h followed by 4 h of reperfusion, while ischemic rats were subjected to 1 h of ischemia only without reperfusion. Testicular-ischemia-induced Beclin 1 and LC3B expression was associated with decreased p62/SQSTM1 expression, increased ATP and alkaline phosphatase (AP) activity, and slightly impaired spermatogenesis. SP600125 treatment improved p62 expression and reduced the levels of Beclin 1 and LC3B but did not affect ATP or AP levels. The tIRI-induced apoptosis lowered the expression of the three ATG proteins and AP activity, activated caspase 3, and caused spermatogenic arrest. SP600125-inhibited JNK during tIRI restored sham levels to all investigated parameters. This study emphasizes the regulatory role of JNK in balancing autophagy and apoptosis during testicular oxidative injuries.

The Impact of Chrysin on The Folliculogenesis and Ovarian Apoptosis in Ischemia-Reperfusion Injury in The Rat Model.

The ovarian Ischemia/reperfusion is one of the gynecological emergency concerns that may lead to the ovary damage and folliculogenesis. The present research aimed to evaluate the impact of the Chrysin (CH) on the ischemia-reperfusion (I/R) injury in the rat model. In this experimental research, 48 adult female rats, 8 weeks age and 180-200 g weight, have been categorized into 6 equal groups (n=8) including one sham and 5 ovarian torsion groups (OT+CH groups) that received different treatments. Each group has been treated 30 min before detorsion with gavage of CH or normal saline for 1 week and pregnant mare serum gonadotropin (PMSG) has been injected on the day 5 for initiating folliculogenesis. Finally, bio-chemical, molecular, histopathological, apoptotic and hormonal evaluations were performed. The anti-oxidant enzyme, superoxide dismutase and glutathione peroxidase, ameliorated in the ovarian tissues of the OT+CH groups in comparison with the OT group (P<0.001). Moreover, the level of serum Luteinizing hormone considerably declined and estradiol level (P<0.001), partly enhanced in the rats treated with CH in comparison with the ones in the OT group (P<0.05). In addition, histopathological scores of the OT+CH groups ameliorated in comparison with the OT group scores (P<0.05). Furthermore, the expression Caspase-3 and Bax genes were significantly increased while the expression of Bcl-2 was notably decreased in the OT group in comparison with the sham group (P<0.05). Here, it seems that CH is possibly beneficial for the protection of ovaries against reperfusion injury and ischemia.

Role of miRNA-1 and miRNA-21 in Acute Myocardial Ischemia-Reperfusion Injury and Their Potential as Therapeutic Strategy.

Coronary artery disease remains the leading cause of death. Acute myocardial infarction (MI) is characterized by decreased blood flow to the coronary arteries, resulting in cardiomyocytes death. The most effective strategy for treating an MI is early and rapid myocardial reperfusion, but restoring blood flow to the ischemic myocardium can induce further damage, known as ischemia-reperfusion (IR) injury. Novel therapeutic strategies are critical to limit myocardial IR injury and improve patient outcomes following reperfusion intervention. miRNAs are small non-coding RNA molecules that have been implicated in attenuating IR injury pathology in pre-clinical rodent models. In this review, we discuss the role of miR-1 and miR-21 in regulating myocardial apoptosis in ischemia-reperfusion injury in the whole heart as well as in different cardiac cell types with special emphasis on cardiomyocytes, fibroblasts, and immune cells. We also examine therapeutic potential of miR-1 and miR-21 in preclinical studies. More research is necessary to understand the cell-specific molecular principles of miRNAs in cardioprotection and application to acute myocardial IR injury.

Effects of Mdivi-1 on Neural Mitochondrial Dysfunction and Mitochondria-Mediated Apoptosis in Ischemia-Reperfusion Injury After Stroke: A Systematic Review of Preclinical Studies.

This systematic review sought to determine the effects of Mitochondrial division inhibitor-1 (Mdivi-1) on neural mitochondrial dysfunction and neural mitochondria-mediated apoptosis in ischemia/reperfusion (I/R) injury after ischemic stroke. Pubmed, Web of Science, and EMBASE databases were searched through July 2021. The studies published in English language that mentioned the effects of Mdivi-1 on neural mitochondrial dysfunction and neural mitochondria-mediated apoptosis in I/R-induced brain injury were included. The CAMARADES checklist (for in vivo studies) and the TOXRTOOL checklist (for in vitro studies) were used for study quality evaluation. Twelve studies were included (median CAMARADES score = 6; TOXRTOOL scores ranging from 16 to 18). All studies investigated neural mitochondrial functions, providing that Mdivi-1 attenuated the mitochondrial membrane potential dissipation, ATP depletion, and complexes I-V abnormalities; enhanced mitochondrial biogenesis, as well as inactivated mitochondrial fission and mitophagy in I/R-induced brain injury. Ten studies analyzed neural mitochondria-mediated apoptosis, showing that Mdivi-1 decreased the levels of mitochondria-mediated proapoptotic factors (AIF, Bax, cytochrome c, caspase-9, and caspase-3) and enhanced the level of antiapoptotic factor (Bcl-2) against I/R-induced brain injury. The findings suggest that Mdivi-1 can protect neural mitochondrial functions, thereby attenuating neural mitochondria-mediated apoptosis in I/R-induced brain injury. Our review supports Mdivi-1 as a potential therapeutic compound to reduce brain damage in ischemic stroke (PROSPERO protocol registration ID: CRD42020205808).Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/], identifier [CRD42020205808].

Pathogenesis of Chronic Allograft Dysfunction Progress to Renal Fibrosis.

Kidney transplantation is a life-change measurement for the patients of end-stage renal disease (ESRD). However, the renal allograft cannot avoid initial acute kidney injury (AKI) and subsequent chronic allograft dysfunction (CAD), gradually develops fibrosis and eventually loses function. It is imperative to disclose the pathogenesis of AKI and CAD in order to facilitate interventions. We have studied the involvement of immunity, inflammation, and apoptosis in ischemia-reperfusion injury (IRI) and/or immunosuppressant induced AKI models, with associated chronic damage. Our research mainly focused on tubular epithelial cells (TECs) that are passive victims and also active participators in injury and mediate following repair or fibrosis. Targeting not only fibroblasts/myofibroblasts, but also TECs, might be a fundamental strategy to prevent and treat renal fibrosis. We have also evaluated the potential application of siRNA targeting caspase-3 and tissue protective erythropoietin derivatives, HBSP and CHBP, aiming to treat AKI and prevent CAD. Significant improvements have been obtained, but timely diagnosis and precise therapy of AKI and prevention of CAD progressing to ESRD are still very challenging. Modern technologies such as microarray and sequencing analysis have been used to identify biomarkers and potentially facilitate individual cell target treatment for transplant patients.

Inhibition Of COX‐2/PGE2/EP4 Signaling Protects Against Post‐hypoxic Apoptosis In H9C2 Cardiomyocytes

Myocardial infarction is a condition associated with significant mortality. Reperfusion therapy restores blood flow, it may also induce lethal tissue injury, known as ischemia‐reperfusion injury (IRI) in clinical practice. Thus, exploring ways to control or attenuate IRI is of clinical interest for improving post‐ischemic recovery. Cyclooxyenase‐2 (COX‐2) – which is induced during ischemia ‐ is highly expressed at the site of recent acute myocardial infarction (Heart. 2004;90:440–443). Furthermore, the presence of COX‐2 is positively correlated with progressively increased apoptosis which played a central role in the pathophysiology of IRI. However, whether there is causal link or underlying signaling cascade between ischemia‐driven COX‐2 expression and apoptosis in IRI is unclear. Thus, the present study aimed to investigate the molecular basis of potential cause‐effect link between COX‐2 expression and enhanced apoptosis during ischemia using rat origin cardiomyocytes (H9C2) subjected to hypoxia/reoxygenation (H/R, 6 hours hypoxia followed by 12 hours reoxygenation). The results showed that H/R significantly increased the protein expression of COX‐2 (P&lt;0.05 vs. Control), which was prevented by 2 hours pretreatment with Helenalin (NFkB inhibitor, at 10μM, P&lt;0.05 vs. H/R) but not by pretreatment with SC‐205346A [Hypoxia inducible factor alpha (HIF‐1α) inhibitor, at 20μM]. This suggests that NFkB but not HIF‐1α mediated the expression of COX‐2 during H/R in H9C2 cardiomyocytes. Further, under the experimental setting, H/R induced H9C2 cells damage [evidenced by increased lactic acid dehydrogenase (LDH) leakage (marker of cell injury, P&lt;0.05 vs. Control)] was concomitant with increased cleaved caspase‐3 expression (marker of cell apoptosis, P&lt;0.05 vs. Control) but no changes in the protein expressions of the anti‐apoptotic Bcl‐2 and pro‐apoptotic Bax, suggesting that H/R induced caspase‐3 dependent cell apoptosis which was independent of the intrinsic mitochondrial pathway. Pretreat the cells with NS398 (COX‐2 selective inhibitor, at 10μM, 1 hour) or L161,982 [prostaglandin E receptor subtype 4 (EP4) selective antagonist, at 100nM, 1 hour] suppressed the H/R induced increases of LDH leakage and cleaved caspase‐3 expression (P&lt;0.05 vs. H/R), indicating that both COX‐2 and EP4 mediated cell apoptosis during H/R. Given that prostaglandin E2 (PGE2) is a major metabolite of COX‐2 and an endogenous ligand of EP4 receptor, H9C2 cardiomyocytes were exposed to exogenous PGE2 (from 5nM to 50μM, 18 hours) in a concentration dependent manner. As anticipated, PGE2, at a high concentration (50μM), significantly increased cellular injury as evidenced by enhanced LDH leakage (P&lt;0.05 vs. Control). It is concluded that H/R may induce cardiomyocytes apoptosis via NFkB/COX‐2/PGE2/EP4 signaling, which may serve as a novel target for anti‐ischemic therapy.Support or Funding InformationThis study was supported by General Research Fund (17124614, and 17123915) from the Research Grants Council of Hong Kong and by National Natural Science Foundation of China (NSFC 81270899).

Inhibition of apoptosis by the intrinsic but not the extrinsic apoptotic pathway in myocardial ischemia-reperfusion

The detailed molecular mechanisms following activation of apoptosis in ischemia-reperfusion injury are unknown. This study using different transgenic mouse models provided first evidence that apoptosis in myocardial ischemia-reperfusion injury is rather linked to the mitochondrial pathway than to death receptor pathway. There is a wealth of evidence for activation of apoptosis in ischemia-reperfusion injury. However, the understanding of detailed molecular mechanism is lacking. The extent of myocardial infarction after ligation of the left anterior descending artery in mice carrying different transgenes for inhibition of either the intrinsic or the extrinsic or a combination of both apoptotic cascades was evaluated. The extent of myocardial damage was assessed by echocardiographic determination of left ventricular (LV) ejection fraction, LV hemodynamics, troponin T, and histology. The rate of apoptosis was analyzed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and caspase-3 staining. Highest perioperative rate of death was observed in the dominant-negative form of a truncated Fas-associated death domain (FADD-DN) group. Infarction size by 2,3,5-triphenyltetrazolium chloride (TTC) staining was smaller in the Bcl-2, but not in the other groups as compared to wild-type mice. This was accompanied by lower troponin T values in Bcl-2 transgenic mice as compared to the all other groups. Troponin T correlated well with macroscopic extent of myocardial infarction by TTC staining. A lower decline of LV ejection fraction was seen in the Bcl-2 as compared to wild-type or FADD-DN mice. A smaller number of TUNEL- and caspase-3-positive myocyte nuclei were observed in the Bcl-2 and FADD-DN group as compared to wild-type mice. We provide first evidence for protective effects on the myocardium in a transgenic mouse model of myocardial ischemia-reperfusion due to inhibition of the Bcl-2, but not the FADD pathway despite that reduced apoptotic cells were observed in both groups as compared to wild-type mice.

Soluble TNF Receptors Are Associated with Infarct Size and Ventricular Dysfunction in ST-Elevation Myocardial Infarction

ObjectivesThe aim of the study was to investigate circulating markers of apoptosis in relation to infarct size, left ventricular dysfunction and remodeling in an ST-elevation myocardial infarction (STEMI) population undergoing primary percutaneous coronary intervention (PCI).BackgroundImmediate re-opening of the acutely occluded infarct-related artery via primary PCI is the treatment of choice in STEMI to limit ischemia injury. However, the sudden re-initiation of blood flow can lead to a local acute inflammatory response with further endothelial and myocardial damage, so-called reperfusion injury. Apoptosis is suggested to be a key event in ischemia-reperfusion injury, resulting in LV-dysfunction, remodeling and heart failure.MethodsThe present study is a prespecified substudy of the F.I.R.E. trial. We included 48 patients with STEMI undergoing primary PCI. Blood samples were collected prior to PCI and after 24 hours. Plasma was separated for later analysis of soluble tumor necrosis factor receptor (sTNFR) 1, sTNFR2, sFas and sFas ligand (sFasL) by ELISA. Infarct size, left ventricular (LV) dysfunction and remodeling were assessed by cardiac magnetic resonance imaging at five days and four months after STEMI.ResultsThe levels of sTNFR1 at 24 h as well as the relative increases in sTNFR1 and sTNFR2 over 24 h showed consistent and significant correlations with infarct size and LV-dysfunction at four months. Moreover, both sTNFRs correlated strongly with Troponin I and matrix metalloproteinase (MMP)-2 measurements. Soluble Fas and sFasL did not overall correlate with measures of infarct size or LV-dysfunction. None of the apoptosis markers correlated significantly with measures of remodeling.ConclusionsIn STEMI patients, circulating levels of sTNFR1 and sTNFR2 are associated with infarct size and LV dysfunction. This provides further evidence for the role of apoptosis in ischemia-reperfusion injury.

The change of the spinal cord ischemia-reperfusion injury in mitochondrial passway and the effect of the Ginkgo biloba extract's preconditioning intervention.

In order to explore whether the apoptosis in ischemia-reperfusion injury could be affected by Ginkgo biloba extract (GBE) and the free radical scavenger GBE could suppress this affection. Rabbits were randomly divided into sham group, ischemia group, ischemia-reperfusion group (1, 6, 24, 48 h), the drug group (1, 6, 24, 48 h). Measure the rate of apoptosis by flow cytometry, the caspase 9 and apoptosis-inducing factor (AIF) in the cytoplasm and serum by ELISA. Compared with the sham group and ischemia group, the reperfusion group increased the rate of apoptosis, the caspase 9 and AIF in serum have a peak at 24 h after reperfusion, in the cytoplasm the peak at 6 h.GBE inhibit performance has the systemic and local aspects. The apoptosis of nerve cells after spinal cord ischemia-reperfusion has the relationship with the mitochondrial caspase-dependent and caspase-independent pathways and both the local and systemic role. GBE inhibits nerve cell apoptosis by these ways.

Sevoflurane postconditioning prevents activation of caspase 3 and 9 through antiapoptotic signaling after myocardial ischemia–reperfusion

Volatile anesthetic postconditioning reduces apoptosis through antiapoptotic signaling. Whether sevoflurane postconditioning prevents activation of caspase 9 and 3, which are implicated in the initiation and execution step of apoptosis, is not known. Isolated perfused guinea pig hearts underwent 30 min global ischemia and 120 min reperfusion [control (CTL)]. Anesthetic postconditioning was elicited with sevoflurane (2%) for 2 min at reperfusion onset (POST). LY294002, phosphatidylinositol-3-kinase (PI3K)/Akt (protein kinase B) inhibitor; and PD98059, extracellular signal-regulated kinase 1/2 (ERK) inhibitor, were administered for 10 min before ischemia and throughout the reperfusion period in POST (POST + LY, POST + PD). Left-ventricular-developed (LVDP) and LV end-diastolic (LVEDP) pressures and infarct size were measured. Western blot analysis determined phosphorylated Akt and ERK expression. Myocardial caspase 3 and 9 were determined immunohistochemically. After ischemia-reperfusion, POST had higher LVDP (57 +/- 9 vs. 38 +/- 7 mmHg, p < 0.05) and lower LVEDP (21 +/- 8 vs. 46 +/- 15 mmHg, p < 0.05) versus CTL. Infarct size was significantly reduced in POST versus CTL (15 +/- 3 vs. 41 +/- 11%, p < 0.001). Phosphorylation of Akt and ERK after reperfusion was significantly increased in POST versus CTL. Immunoreactivity for caspase 3 and 9 was greater in the nucleus of myocytes and endothelial cells in CTL. POST attenuated this increased immunoreactivity. LY294002 and PD98059 abolished the effect of POST on caspase 3 and 9 immunoreactivity. Sevoflurane postconditioning prevents activation of caspase 3 and 9, mediators of apoptosis in ischemia-reperfusion injury. This caspase activation is mediated by phosphorylation of Akt and ERK.

Effect of nadcin on energy supply system and apoptosis in ischemia-reperfusion injury to the myocardium

Nadcin in a dose of 90 mg/kg administered to dogs with subacute stage of ischemia-reperfusion myocardial injury immediately after blood flow resumption normalized redox potential of cardiomyocytes and mitochondria and restored the total content of adenyl and pyridine nucleotides. The decrease in the synthesis of ATP and pyridine nucleotides and reduction of the redox potential of the energy supply system were inversely related to the increase in poly-(ADP-ribose)-polymerase activity in the ischemic area and nonischemic region. Nadcin abolished the increase in poly-(ADP-ribose)-polymerase activity in the ischemic area of the right ventricle, nonischemic region, and ischemic area of the left ventricle (by 2.4, 2.9, and 1.52 times, respectively) and normalized bioenergetic activity of cardiomyocytes during ischemia-reperfusion myocardial injury.

Caspase Inhibition Enhances Ischemic Tolerance of Fasciocutaneous Flaps

To demonstrate the significance of apoptosis in ischemia-reperfusion injury in revascularized fasciocutaneous flaps and test the hypothesis that pharmacologic inhibition of caspases prolongs the allowable primary ischemia time of these flaps. Animal study using the epigastric flap in adult male Sprague-Dawley rats. Fifty-nine rats were treated with the caspase inhibitor (Q-VD-OPH) reconstituted in dimethylsulfoxide (DMSO) (n = 20, 8 mg/kg:0.8 mL/kg), DMSO alone (n = 19, 0.8 mL/kg), or saline (n = 20, 0.8 mL/kg). Treatment was given as a single intraperitoneal injection 30 minutes before starting primary ischemia. Epigastric flaps were subjected to increasing ischemia times followed by reperfusion. The flaps were harvested and analyzed 7 days later, and viability was assessed. Probit statistical analysis was used to determine the critical ischemia time. This was defined as the time point when 50% of the flaps in each group were expected to survive. The calculated critical ischemia times were 8.92 hours (95% confidence interval 7.19-10.47 h) for the saline group, 16.35 hours (95% confidence interval 11.82-19.89 h) for the DMSO group, and 21.73 hours (95% confidence interval 19.39-25.37 h) for the DMSO with Q-VD-OPH group. These differences were significantly different from each other. Pretreatment of fasciocutaneous flaps with a free radical scavenger alone or in combination with a caspase inhibitor significantly increases the flap's tolerance of primary ischemia. The added benefit of the caspase inhibitor suggests that apoptosis plays an important role in ischemia-reperfusion injury in soft tissue flaps.

IN VIVO EFFECTS OF CO-RELEASING MOLECULES: PRELIMINARY DATA IN A LARGE ANIMAL MODEL

P85 Introduction: Carbon monoxide (CO) administration has been shown to protect from ischemia reperfusion (IR) injury associated with organ transplantation. However, CO administration by gas inhalation, as currently done in experimental transplantation, offers the disadvantage of being complicated and unpractical particularly with regard to its possible future clinical application. Therefore, we have studied the potential therapeutic effects of a recently generated CO-releasing molecule (CO-RM) as a new mode of administering CO for clinical use. Methods: In a preliminary pharmacodynamic study in the pig, tricarbonylchloro(glycinato) ruthenium(II) (CORM-3) was administered as a single dose of 4 mg/kg i.v. into two Large White pigs. PBMC isolated at 2, 6, 12, 24, 48, 72 and 168 hrs after CORM-3 administration, were stimulated in vitro with 1-10 μg/ml LPS and the production of TNF-α, one of the key initiators of apoptosis in IR injury, was evaluated by ELISA. Subsequently, four immunosuppressed Large White pigs were induced with 4 mg/kg of CORM-3 one day before renal transplantation and received the drug at 1 mg/kg or 4 mg/kg every second day until the end of the experiment. In these allograft recipients, the efficacy of CORM-3 on the in vitro production of TNF-α was evaluated on the day of transplantation and at the time of euthanasia. All the routine haematological and biochemical parameters were monitored throughout the experiments. Results: A single dose of 4 mg/kg of CORM-3 was able to significantly reduce TNF-α production by PBMC starting from 24 hrs after administration. This effect was maintained for 48 hrs. 72 hrs after a single dose treatment, the levels of TNF-α were back to the control pre-dose values or even higher. The efficacy of CORM-3 as an inhibitor of TNF-α production has also been observed in allotransplanted pigs where PBMC isolated after 24 hr treatment with CORM-3 were unable to release TNF-α after LPS stimulation. In these animals, CORM-3 administration was not associated with any noticeable side-effects. Conclusion: At the doses used in this study, in vivo administration of CORM-3 in a large animal model is well-tolerated and is able to interfere with TNF-α production by PBMC. As TNF-α is a key initiator of the apoptotic events in IR injury, it is expected that this approach may prove useful for the long term survival of transplanted organs.

Inhaled nitric oxide attenuates apoptosis in ischemia-reperfusion injury of the rabbit lung

BackgroundLung ischemia-reperfusion injury occurs after lung transplantation and various clinical procedures. Recently, apoptosis was reported to be induced after ischemia-reperfusion. We investigated the effects of inhaled nitric oxide (NO) on lung ischemia-reperfusion and apoptosis after ischemia-reperfusion. MethodsAs a control group, the left pulmonary hilum of Japanese white rabbits (n = 10) was occluded for 120 minutes and reperfused for 120 minutes. In the inhaled NO group (n = 10), 20 parts per million nitric oxide was inhaled during reperfusion. The sham-operated group was ligated at the right hilum and perfused by the left lung only for 120 minutes. The mean pulmonary arterial pressures and Pao2 were measured during reperfusion. The wet-to-dry weight ratio of the left lower lobe of the lung was calculated. The number of apoptotic cells was estimated using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) technique. The TUNEL staining for a time course study was done using 15 control animals that were killed by exsanguination at 15, 30, and 60 minutes after reperfusion. ResultsAfter 120 minutes of reperfusion, the mean pulmonary arterial pressures in the control group and in the inhaled NO group were 23.0 ± 3.2 mm Hg and 13.6 ± 2.4 mm Hg, respectively (p < 0.01). At the same time point, the Pao2 in the control group and in the inhaled NO group were 46.1 ± 15.9 mm Hg and 88.1 ± 14.7 mm Hg, respectively (p < 0.01). The wet-to-dry weight ratios in the control group and in the inhaled NO group were 0.856 ± 0.024 and 0.808 ± 0.006, respectively (p < 0.01). Apoptotic cells appeared in the early phase of reperfusion (after 15 minutes' reperfusion). The number of apoptotic cells was significantly lower in the inhaled group than in the control group after 120 minutes' reperfusion (1.76% versus 2.87%, p < 0.01). ConclusionsOur results suggest that the inhaled NO prevents lung ischemia-reperfusion injury and attenuates apoptosis after reperfusion in the rabbit lung.

Melatonin protects against ischemia-reperfusion injury and inhibits apoptosis in isolated working rat heart

Introduction: Melatonin (MEL), a pineal hormone, is well known as a potent antioxidant in a variety of ischemia-reperfusion models. Recent studies have assumed a pivotal role of reactive oxygen species (ROS) in the development of apoptosis. There are few pieces of information concerning a possible protective role of MEL against apoptosis in ischemia-reperfusion injury of myocardium. Methods: We conducted an in vitro experiment: (1) to study the effect of MEL in the model of isolated and perfused working rat heart; (2) to evaluate the antioxidant capacity of MEL by a simple fluorescence test; and (3) to analyze the extent of apoptosis inhibition by MEL. Four groups of male Wistar rat were used: (a) group ‘MEL 50 μM’ ( n=8); (b) group ‘ischemia 30 min’ ( n=8); (c) group ‘controls’ ( n=8); and (d) group ‘controls+MEL 50 μM’ ( n=8). The perfusion medium was an oxygenated Krebs–Henseleit buffer (KHB). Hearts in groups (a) and (b) underwent 30 min of global normothermic ischemia and 45 min of reperfusion; 3 min before ischemia the hearts of group (a) received KHB with MEL 50 μM (and MEL 50 μM was also present in KHB solution during reperfusion). Hearts of group (c) were only perfused by KHB, and hearts of group (d) perfused by KHB+MEL 50 μM throughout the experiment. Registered were basic hemodynamic parameters: coronary, aortic, cardiac output and heart rate. At the end of each experiment, a left ventricle samples were taken for in situ detection of apoptosis using a TUNEL in-situ detection kit (POD) and quantitative analysis was performed. Malonedialdehyde concentrations were evaluated from heart homogenate to determine the severity of oxidative damage. To study the antioxidant capacity of MEL, a fluorescence test with allophycocyanin as an indicator was performed. A peroxyl radical generator, 2,2′-azobis(2-amidinopropan)-4-hydrochloride (AAPH) was used, and the antioxidant effect of MEL was expressed in oxygen-radical absorbing capacity (ORAC) units. Results: Treatment by MEL resulted in a significant improvement of hemodynamic parameters and reduction of postischemic arrhythmias during reperfusion. All hearts in group ‘ischemia 30 min’ developed fatal ventricular fibrillations. MEL significantly reduced the incidence of apoptotic cells (14±4.3%; ** P<0.01) vs. group ‘ischemia 30 min’ (58±2.1%). No apoptotic cells were detected in both control groups (c) and (d). In the fluorescence test, MEL exhibited a significant dose-dependent protective effect against peroxyl radical; MEL also reduced significantly the level of lipoperoxidation (MDA; * P<0.05). Analysis of hemodynamic parameters in both control groups (c) and (d) did not show any significant differences; the presence of MEL 50 μM in KHB solution did not have any important influence on cardiac performance in this type of experiment. Conclusion: We confirmed the previously reported beneficial effects of MEL against ischemia-reperfusion injury, presumably via its antioxidant properties. A significant suppression of apoptosis and the peroxyl radical scavenging properties of MEL in our study could contribute to the hypothesis of a close link between oxidative stress and apoptosis promotion.