Acute Ischemia-reperfusion Research Articles

The adipokine progranulin protects against ischemia reperfusion-induced arrhythmias in a rat model

Background and Aims : Acute myocardial infarction is precipitated by occlusion of the coronary arteries resulting in sudden death. Restoration of coronary flow has damaging effects on cardiac myocytes causing an increase in infarct size and lethal arrhythmias due to ischemia-reperfusion injury. Progranulin, an adipokine, has shown cardioprotective properties and has been expressed in atherosclerotic tissue, however, its effect on ischemia reperfusion-induced arrhythmias has not been explored. The study at hand examines the effect of progranulin on ischemia reperfusion-induced arrhythmias in a rat model of acute myocardial ischemia-reperfusion injury.

Hypothermia Prevents Cardiac Dysfunction during Acute Ischemia Reperfusion by Maintaining Mitochondrial Bioenergetics and by Promoting Hexokinase II Binding to Mitochondria.

Background Hypothermia (H), cardioplegia (CP), and both combined (HCP) are known to be protective against myocardial ischemia reperfusion (IR) injury. Mitochondria have molecular signaling mechanisms that are associated with both cell survival and cell death. In this study, we investigated the dynamic changes in proapoptotic and prosurvival signaling pathways mediating H, CP, or HCP-induced protection of mitochondrial function after acute myocardial IR injury. Methods Rats were divided into five groups. Each group consists of 3 subgroups based on a specific reperfusion time (5, 20, or 60 min) after a 25-min global ischemia. The time control (TC) groups were not subjected to IR but were perfused with 37 °C Krebs-Ringer's (KR) buffer, containing 4.5 mM K+, in a specific perfusion protocol that corresponded with the duration of each IR protocol. The IR group (control) was perfused for 20 min with KR, followed by 25-min global ischemia, and then KR reperfusion for 5, 20, or 60 min. The treatment groups were exposed to 17 °C H, 37 °C CP (16 mM K+), or HCP (17 °C + CP) for 5 min before ischemia and for 2 min on reperfusion before switching to 37 °C KR perfusion for the remainder of each of the reperfusion times. Cardiac function and mitochondrial redox state (NADH/FAD) were monitored online in the ex vivo hearts before, during, and after ischemia. Mitochondria were isolated at the end of each specified reperfusion time, and changes in O2 consumption, membrane potential (ΔΨm), and Ca2+ retention capacity (CRC) were assessed using complex I and complex II substrates. In another set of hearts, mitochondrial and cytosolic fractions were isolated after a specified reperfusion time to conduct western blot assays to determine hexokinase II (HKII) and Bax binding/translocation to mitochondria, cytosolic pAkt levels, and cytochrome c (Cyto-c) release into the cytosol. Results H and HCP were more protective of mitochondrial integrity and, concomitantly, cardiac function than CP alone; H and HCP improved post-ischemic cardiac function by (1) maintaining mitochondrial bioenergetics, (2) maintaining HKII binding to mitochondria with an increase in pAkt levels, (3) increasing CRC, and (4) decreasing Cyto-c release during reperfusion. Bax translocation/binding to mitochondria was unaffected by any treatment, regardless of cardiac functional recovery. Conclusions Hypothermia preserved mitochondrial function and cardiac function, in part, by maintaining mitochondrial bioenergetics, by retaining HKII binding to mitochondria via upstream pAkt, and by reducing Cyto-c release independently of Bax binding to mitochondria.

Albendazole ameliorates inflammatory response in a rat model of acute mesenteric ischemia reperfusion injury

BackgroundAcute mesenteric ischemia is known as a life threatening condition. Re-establishment of blood flow in this condition can lead to mesenteric ischemia reperfusion (MIR) injury which is accompanied by inflammatory response. Still, clear blueprint of inflammatory mechanism underlying MIR injury has not been provided. Interestingly, Albendazole has exhibited notable effects on inflammation and cytokine production. In this study, we aimed to evaluate outcomes of MIR injury following pretreatment with Albendazole with respect to assessment of mesenteric inflammation and ischemia threshold. MethodsMale rats were randomly divided into sham operated, vehicle treated, Albendazole 100 mg/kg and Albendazole 200 mg/kg groups. MIR injury was induced by occlusion of superior mesenteric artery for 30 min followed by 120 min of reperfusion. Samples were utilized for assessment of epithelial survival and villous height. Immunohistochemistry study revealed intestinal expression of TNF-α and HIF-1-α. Gene expression of NF-κB/TLR4/TNF-α/IL-6 was measured using RTPCR. Also protein levels of inflammatory cytokines in serum and intestine were assessed by ELISA method. ResultsHistopathological study demonstrated that pretreatment with Albendazole could ameliorate decline in villous height and epithelial survival following MIR injury. Also, systemic inflammation was suppressed after administration of Albendazole. Analysis of possible participating inflammatory pathway could demonstrate that intestinal expression of NF-κB/TLR4/TNF-α/IL-6 is significantly attenuated in treated groups. Eventually, IHC study illustrated concordant decline in mesenteric expression of HIF-1-α/TNF-α. ConclusionSingle dose pretreatment with Albendazole could ameliorate inflammatory response and enhance ischemia threshold following induction of MIR injury. More studies would clarify existing causality in this phenomenon.

Hinokitiol Protects Cardiomyocyte from Oxidative Damage by Inhibiting GSK3β-Mediated Autophagy.

More and more attention has been paid to the use of traditional phytochemicals. Here, we first verified the therapeutic potential of a natural bioactive compound called Hinokitiol in myocardial ischemia reperfusion injury. Hinokitiol exerts cardioprotective effect through inhibition of GSK-3β and subsequent elimination of excessive autophagy, tuning autophagic activity in moderate extent for remedial profit in acute myocardial infarction and myocardial ischemia reperfusion injury. Overall, our study establishes Hinokitiol as a novel available interventional treatment for myocardial ischemia reperfusion injury.

PPARγ Mediates the Cardioprotective Roles of Danlou Tablet After Acute Myocardial Ischemia-Reperfusion Injury.

Ischemic heart disease is one of the biggest threats to human life in the world. Reperfusion therapy is an effective strategy to reduce infarct size and ischemic injury. However, reperfusion process may cause secondary myocardial injury which is defined as ischemia-reperfusion injury (IRI). Exploring potential therapeutic strategy to attenuate IRI is extremely important. Danlou tablet (Dan), a Chinese herbal compound consisting of ten herbs, has been identified to be protective for the heart. However, the mechanism of Dan-induced cardioprotection after acute reperfusion was unelucidated. In this study, to investigate the role and mechanism of Dan in myocardial IRI, we performed acute IRI modeling in mice and oxygen-glucose deprivation–reperfusion (OGD/R)-induced apoptosis in primary neonatal rat cardiomyocytes (NRCMs). We found that Dan had protective effect against acute IRI in mice, as evidenced by reduced infarct size, TUNEL-positive cardiomyocytes (CMs), and Bax/Bcl2 ratio and cleaved-caspase 3/caspase 3 ratio in vivo. Meanwhile, Dan inhibited OGD/R-induced apoptosis of NRCMs in vitro. Mechanistically, Dan could activate proliferator-activated receptor gamma (PPARγ) in both IRI hearts and OGD/R-stressed NRCMs, while inhibition of PPARγ attenuated the protective effect of Dan against IRI in vivo and OGD/R-induced CM apoptosis in vitro. These data reveal that Dan attenuates acute myocardial IRI and CM apoptosis through activating PPARγ. Our findings may extend the knowledge of Chinese medicine and provide potential strategy for the precise treatment of ischemic heart diseases.

AMPK Activation Is Indispensable for the Protective Effects of Caloric Restriction on Left Ventricular Function in Postinfarct Myocardium

Simple SummaryImpaired coronary blood flow induces cardiac ischemia and can lead to myocardial infarction. Although revascularization therapy and medical treatment potentially restore cardiac function in ischemic hearts, loss of cardiomyocytes and replacement of the dead myocardium by a scar can lead to ischemic heart disease with impaired cardiac output, a condition called heart failure. Medical treatment of heart failure includes drugs such as ACE-inhibitors, beta-blockers, diuretics, mineralocorticoid receptor antagonists, and SGLT (sodium-glucose cotransporter) 2 inhibitors. In addition, dietary interventions may provide further benefits to slow down disease progression. Caloric restriction, the decrease in calorie intake without malnutrition, is a strategy for improving health and increasing lifespan. Caloric restriction reduces the risk factors for cardiovascular diseases, and it improves heart function in animals and humans. Our study investigated the impact of caloric restriction on heart failure progression in mice and rats with myocardial infarction. We show that caloric restriction inhibits progressive loss of heart function, even when started after heart failure is already established. Together, the findings help to deepen our understanding of the complex mechanisms involved in the cardioprotective effects of caloric restriction and how they could be therapeutically utilized to prevent disease progression.Background: Caloric restriction (CR) extends lifespan in many species, including mammals. CR is cardioprotective in senescent myocardium by correcting pre-existing mitochondrial dysfunction and apoptotic activation. Furthermore, it confers cardioprotection against acute ischemia-reperfusion injury. Here, we investigated the role of AMP-activated protein kinase (AMPK) in mediating the cardioprotective CR effects in failing, postinfarct myocardium. Methods: Ligation of the left coronary artery or sham operation was performed in rats and mice. Four weeks after surgery, left ventricular (LV) function was analyzed by echocardiography, and animals were assigned to different feeding groups (control diet or 40% CR, 8 weeks) as matched pairs. The role of AMPK was investigated with an AMPK inhibitor in rats or the use of alpha 2 AMPK knock-out mice. Results: CR resulted in a significant improvement in LV function, compared to postinfarct animals receiving control diet in both species. The improvement in LV function was accompanied by a reduction in serum BNP, decrease in LV proapoptotic activation, and increase in mitochondrial biogenesis in the LV. Inhibition or loss of AMPK prevented most of these changes. Conclusions: The failing, postischemic heart is protected from progressive loss of LV systolic function by CR. AMPK activation is indispensable for these protective effects.

Estradiol Ameliorates Acute Kidney Ischemia-Reperfusion Injury by Inhibiting the TGF-βRI-SMAD Pathway.

Renal ischemia–reperfusion injury (IRI) is less extensive in females than males in both animals and humans; however, this protection diminishes after menopause, suggesting that estrogen plays a pivotal role in IRI, but the underlying mechanism remains largely unknown. Our study found that 45 min of warm ischemia was sufficient to induce significant pathological changes without causing death in model animals. Compared with male rats, female rats exhibited less extensive apoptosis, kidney injury, and fibrosis; these effects were worsened in ovariectomized (OVX) rats and ameliorated upon estradiol (E2) supplementation. Furthermore, the levels of TGF-βRI, but not TGF-βRII or TGF-β1, were significantly increased in OVX rats, accompanied by phosphorylated SMAD2/3 activation. Interestingly, the alteration trend of the nuclear ERα level was opposite that of TGF-βRI. Furthermore, dual luciferase reporter and chromatin immunoprecipitation assays showed that ERα could bind to the promoter region of TGF-βRI and negatively regulate its mRNA expression. Moreover, an in vitro study using NRK-52E cells showed that ERα knockdown blocked E2-mediated protection, while TGF-βRI knockdown protected cells against hypoxic insult. The findings of this study suggest that renal IRI is closely related to the TGF-βRI-SMAD pathway in females and that E2 exert its protective effect via the ERα-mediated transcriptional inhibition of TGF-βRI expression.

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.

The nuclear receptor co-repressor 1 is a novel cardioprotective factor against acute myocardial ischemia-reperfusion injury

Acute myocardial ischemia/reperfusion (MI/R) is a major determinant of prognosis in myocardial infarction patients, while effective therapies are currently lacking. Nuclear receptor co-repressor 1 (NCoR1) is emerging as a critical regulator of cell survival and death signaling in mammals. However, the role of NCoR1 in the pathogenesis of acute MI/R injury remains unknown. Here, we observed that NCoR1 was highly expressed in the mouse heart and significantly downregulated after acute MI/R injury. Cardiomyocyte-specific NCoR1 deletion led to significantly increased infarct size and exacerbated cardiac dysfunction compared to wild-type littermates. Moreover, cardiomyocyte-specific NCoR1 deficiency exacerbated MI/R-induced mitochondrial dysfunction and apoptotic pathway activation. Transcriptomic profiling results indicated that cardiomyocyte-specific NCoR1 deficiency pivotally promoted activation of inflammatory pathways. Through integrated omics analysis, signal transducer and activator of transcription 1 (STAT1) was identified as a downstream target trans-repressed by NCoR1. STAT1 activation played a key mediating role in the detrimental effects of NCoR1 deficiency in MI/R injury. Collectively, our findings provided the first evidence that cardiomyocyte-expressed NCoR1 functioned as a crucial cardioprotective factor against acute MI/R injury by targeting the STAT1 pathway in heart.

Analysis of microRNA Expression after Glutamine Intervention in Acute Renal Ischemia-Reperfusion Injury.

Background Ischemia-reperfusion acute kidney injury (I/R AKI) is a severe kidney disease with high mortality and morbidity. This study aimed to explore the protective mechanism of glutamine (GLN) against I/R AKI. MethodsThe I/R AKI rat model was established, and HE staining of kidney tissue and serum creatinine (SCr) and blood urea nitrogen (BUN) detection were performed. The miRNAs were sequenced by high throughput in rat kidney tissue samples. Differentially expressed miRNAs (DEmiRs) between the I/R group and I/R + GLN group were screened, and enrichment analysis for target genes of DEmiRs was performed. Meanwhile, human HK-2 cells were cultured, and an I/R model was established to verify the expression of DEmiRs. Results Compared with the I/R group, the SCr and BUN levels at each time point were lower in the I/R + GLN group. Vacuolar degeneration of renal tubules in the I/R + GLN group was significantly reduced. In the 104 DEmiRs, we selected miR-132-5p, miR-205, and miR-615 as key miRNAs. KEGG analysis showed that the Notch signaling pathway, PI3K-Akt signaling pathway, and cGMP signaling pathway were mainly related to the GLN against I/R. qRT-PCR verified the downregulation of miR-205 in the I/R group, compared to the sham and I/R + GLN group. The I/R model was established with HK-2 cells, and the expression of miR-132-5p and miR-205 was decreased. Conclusion GLN reduced I/R-induced AKI. There were significant differences between miRNAs expression in I/R after GLN treatment. The process of GLN against I/R-induced AKI may be related to the Notch and PI3K-Akt signaling pathway.

Impact of Acute Ischemia-Reperfusion Injury on Left Ventricular Pressure-Volume Relations in Dogs

Objective: Ischemic conditioning (IC) limits myocyte necrosis after acute myocardial ischemia-reperfusion; however, controversy persists regarding its potential to attenuate LV contractile dysfunction. Pressure-volume (P-V) loop analysis, via the load-insensitive conductance catheter method, was used to evaluate LV contractility, diastolic function, and ventriculo-arterial coupling. The goal of this study was to evaluate the ability of IC to improve post-ischemic recovery of LV contractile function. Methods: Twelve anesthetized dogs were randomly distributed to either the IC or the non-IC group; all dogs were subject to 60-min acute coronary occlusion followed by 180-min reperfusion. IC consisted of 4 repeated cycles of 5-min occlusion and 5-min reperfusion of the left main coronary artery. LV P-V relations were constructed under steady-state conditions (by inferior vena cava occlusion) at the beginning and end of the experiments; P-V loops were acquired at different time points before and during ischemia-reperfusion. Results: During ischemia and reperfusion, dP/dtmax decreased significantly compared to baseline in both groups; dP/dtmin, an indicator of the rate of LV relaxation rate was not affected for either group. Significant changes in several parameters of LV function including LVEF, SW, tPFR, ESV, and EDV caused by ischemia were also identified; none of these negative effects were resorbed, even in part, during reperfusion. Conclusions: Diminished LV contractile efficiency during systole and diastole produced by ischemia-reperfusion did not improve with IC pre-treatment despite significant endogenous protection against tissue necrosis.

Lupeol Alleviates Myocardial Ischemia-Reperfusion Injury in Rats by Regulating NF-[Formula: see text]B and Nrf2 Pathways.

Cardiovascular disease is a global health problem. Previous studies revealed that it involves acute myocardial infarction and ischemia-reperfusion (I/R) injury. The mechanism of myocardial I/R injury is complex. But recognizing its mechanisms will bring important clinical significance. Lupeol is widely found in Chinese medicinal herbs and has been shown to have a variety of bio-activities. However, the pharmacological action of lupeol in the progress of myocardial ischemia-reperfusion injury (MIRI) is unclear. This study used a rat myocardial I/R model and the morphological changes in myocardium were determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining. The expression levels of IL-10, IL-1[Formula: see text], TNF-[Formula: see text], and IL-6 were assessed by quantitative real-time PCR (qRT-PCR) and ELISA. The expression levels of MB isoenzyme of creatine kinase (CK-MB), lactate dehydrogenase (LDH) level and inflammatory cytokines were quantified using ELISA. The cellular apoptotic rate was determined by TUNEL staining. The findings showed that lupeol significantly decreased myocardial infarction after I/R and ameliorated I/R-induced myocardial inflammation, apoptosis, and oxidative stress. Furthermore, our results suggested that lupeol protected against MIRI-induced myocardial infarction through modulation of NF-[Formula: see text]B and Nrf2 signaling pathways. In summary, this study first clarified the cardioprotective effects of lupeol against I/R-induced myocardial infarction in rats, which could be due to its anti-oxidant, anti-inflammatory, and anti-apoptotic activities. Our study also highlighted a mechanism of NF-[Formula: see text]B and Nrf2 signaling, through which lupeol could be a promising agent in protecting against I/R-induced myocardial infarction.

The role of nitric oxide on the antiarrhythmic effects of ketamine/xylazine in a rat model of acute cardiac ischemia-reperfusion.

The prevalence of ventricular arrhythmias during general anesthesia is about 70%. In experimental studies on the antiarrhythmic effects of different agents, using anesthetic drugs that do not have any protective properties are preferable. The present study was conducted to investigate molecular mechanisms involved in the antiarrhythmic effects of ketamine/xylazine (K/X).Sixty male rats were assigned to eight groups: K/X, L -NAME (25–35 mg/kg) with thiopental (TP), L-NAME (25–35 mg/kg) with ketamine/xylazine, L arginine (100 mg/kg) with thiopental, L-arginine (100 mg/kg) with ketamine/xylazine. After anesthetic induction using TP or K/X, the animals were subjected to 30 min of ischemia. Hemodynamic parameters, ventricular arrhythmias during ischemia, the incidence of ventricular tachycardia (VT), and ventricular fibrillation (VF) were measured. Additionally, in order to assess nitrite/nitrate ratio and LDH after ischemia, serum samples were collected and used.Our results showed that in the K/X group, the number of VT and VF, duration of VT (p = 0.006), the severity of arrhythmias (p = 0.0179). There was no VF incidence in this group.These protective effects were faded by administration of L-NAME with K/X. The combination of L- Arginine in the TP group decreased the number and duration of VT (p < 0.001, p = 0.0013) with no incidence of VF in comparison with TP. L-arginine with K/X groups increased the number and duration of VT (p < 0.0001, p < 0.001) compared to K/X and VF was seen (100%). However, there was no significant difference between TP and K/X groups in terms of this nitrite/nitrate ratio. These findings suggest that the antiarrhythmic effects of ketamine/xylazine might be partially relative to the nitric oxide synthesis pathway.

Human Lysyl Oxidase Over-Expression Enhances Baseline Cardiac Oxidative Stress but Does Not Aggravate ROS Generation or Infarct Size Following Myocardial Ischemia-Reperfusion

Lysyl oxidase (LOX) is an enzyme critically involved in collagen maturation, whose activity releases H2O2 as a by-product. Previous studies demonstrated that LOX over-expression enhances reactive oxygen species (ROS) production and exacerbates cardiac remodeling induced by pressure overload. However, whether LOX influences acute myocardial infarction and post-infarct left ventricular remodeling and the contribution of LOX to myocardial oxidative stress following ischemia-reperfusion have not been analyzed. Isolated hearts from transgenic mice over-expressing human LOX in the heart (TgLOX) and wild-type (WT) littermates were subjected to global ischemia and reperfusion. Although under basal conditions LOX transgenesis is associated with higher cardiac superoxide levels than WT mice, no differences in ROS production were detected in ischemic hearts and a comparable acute ischemia-reperfusion injury was observed (infarct size: 56.24 ± 9.44 vs. 48.63 ± 2.99% of cardiac weight in WT and TgLOX, respectively). Further, similar changes in cardiac dimensions and function were observed in TgLOX and WT mice 28 days after myocardial infarction induced by transient left anterior descending (LAD) coronary artery occlusion, and no differences in scar area were detected (20.29 ± 3.10 vs. 21.83 ± 2.83% of left ventricle). Our data evidence that, although LOX transgenesis induces baseline myocardial oxidative stress, neither ROS production, infarct size, nor post-infarction cardiac remodeling were exacerbated following myocardial ischemia-reperfusion.

Total Flavonoids of Chuju Decrease Oxidative Stress and Cell Apoptosis in Ischemic Stroke Rats: Network and Experimental Analyses.

Background: Pharmacological research results showed that total flavonoids of Chuju (TFCJ) could be used to treat acute myocardial ischemia and myocardial ischemia-reperfusion injury. In this study, we explored the protective effect of TFCJ on ischemic stroke (IS) in the IS rat model. We hypothesized that TFCJ might exert its neuroprotective effects by suppressing apoptosis and oxidative stress that are closely related to PI3K/Akt/mTOR signaling pathway.Method: TFCJ (10, 20, and 40 mg/kg) was administered for 7 days. Rats (260 ± 20 g) were subjected to middle cerebral artery occlusion (MCAO) for 2 h and reperfusion for 24 h. The neuroprotective effect of TFCJ was substantiated in terms of neurological deficits, oxidative stress (superoxide dismutase, glutathione peroxidase, catalase, and malondialdehyde), pathomorphological changes (HE staining and TUNEL staining), and neurobehavioral functions in the rats. Then, we employed network pharmacology to reveal the potential mechanism of TFCJ against IS. Western blot was used to determine the levels of PI3K/AKT/mTOR pathway proteins. The expression of BCL-2, BAX, and cleaved-Caspase-3 was also measured by Western blots and RT-PCR.Results: The histopathological assessment showed that TFCJ reduced MCAO-induced brain damage. Besides, TFCJ exerted a protective role in MCAO rats by alleviating cell apoptosis and oxidative stress. Network pharmacology showed that TFCJ might be used against IS through the PI3K/AKT signaling pathway. TFCJ reduced cell apoptosis and oxidative stress by increasing the level of p-AKT and p-mTOR in MCAO rats, while the effect of TFCJ was significantly reversed when applying LY294002 (PI3k inhibitor).Conclusion: These results indicated that TFCJ might decrease oxidative stress and apoptosis that are closely related to PI3K/Akt/mTOR pathway in IS. TFCJ is a promising authentic traditional Chinese medicine for the management of IS.

Matrix Metalloproteinase-2 Inhibition in Acute Ischemia-Reperfusion Heart Injury-Cardioprotective Properties of Carvedilol.

Matrix metalloproteinase 2 (MMP-2) is activated in hearts upon ischemia-reperfusion (IR) injury and cleaves sarcomeric proteins. It was shown that carvedilol and nebivolol reduced the activity of different MMPs. Hence, we hypothesized that they could reduce MMPs activation in myocytes, and therefore, protect against cardiac contractile dysfunction related with IR injury. Isolated rat hearts were subjected to either control aerobic perfusion or IR injury: 25 min of aerobic perfusion, followed by 20 min global, no-flow ischemia, and reperfusion for 30 min. The effects of carvedilol, nebivolol, or metoprolol were evaluated in hearts subjected to IR injury. Cardiac mechanical function and MMP-2 activity in the heart homogenates and coronary effluent were assessed along with troponin I content in the former. Only carvedilol improved the recovery of mechanical function at the end of reperfusion compared to IR injury hearts. IR injury induced the activation and release of MMP-2 into the coronary effluent during reperfusion. MMP-2 activity in the coronary effluent increased in the IR injury group and this was prevented by carvedilol. Troponin I levels decreased by 73% in IR hearts and this was abolished by carvedilol. Conclusions: These data suggest that the cardioprotective effect of carvedilol in myocardial IR injury may be mediated by inhibiting MMP-2 activation.

The effect of mesenchymal stromal cells of various origins on mortality and neurologic deficit in acute ischemia-reperfusion in rats

Stroke is a global epidemic issue and the second leading cause of death in the world and in Ukraine. According to official statistics, every year 100-110 thousand Ukrainians suffer acute cerebrovascular disorders. One third of such patients are of working age, up to 50 % will have a disability, and only one in ten will fully return to full life. So far, promising experimental data on the treatment of neurological dysfunction using mesenchymal stromal cells (MSCs) have been obtained. The aim of study is to compare the effect of MSCs of different origins on mortality and neurologic deficit in rats with acute cerebral ischemia-reperfusion injury (CIRI). Materials and methods. Transient bilateral 20-minute occlusion of internal carotid arteries was modeled in male Wistar rats aged 4 months and animals were injected intravenously with MSCs derived from human umbilical cord Wharton's-jelly (hWJ-MSC), human and rat adipose tissue. Other groups of experimental animals were injected intravenously with rat fetal fibroblasts and cell lysate from hWJ-MSC. The last group of rats received Citicoline at a dose of 250 mg/kg as a reference drug. Control animals were injected intravenously with normal saline. The cerebroprotective effect of therapy was assessed by mortality and neurologic deficit in rats on the McGraw's stroke index score. Results. After 12 hours of observation in the crucial period in the development of experimental acute cerebrovascular disorders with the administration of hWJ-MSC, mortality was only 10 % against 45 % of animals in the control group. The use of rat fetal fibroblasts reduced the mortality of animals compare to the control group by an average of 25 %. CIRI in rats caused severe neurologic deficits: paralysis, paresis, ptosis, circling behavior. On the 7th day of observation in the control group of animals, the mean score on the McGrow's stroke index indicated severe neurological disorders. On the 14th day of observation in this group of animals there was no complete recovery of lost central nervous system functions. Compared with the control group of animals, all the treatment agents for acute CIRI (MSCs of various origins, MSC's lysate and Citicoline) contributed to a significant regression of neurologic deficit. Conclusions. Thus, transplantation of human Wharton's jelly-derived MSCs and rat fetal fibroblasts reduced mortality and alleviated neurological symptoms in rats with experimental ischemic stroke. hWJ-MSC, rat fetal fibroblasts, and rat adipose-derived MSCs reduced the incidence of neurological disorders better than Citicoline, which was accompanied by a regression of neurologic deficit dynamics on the 14th day of follow-up. The ability of stem cells of different origins to reduce neurologic deficit indicates the feasibility of their use in experimental acute cerebral ischemia.

Can Erythropoietin Reduce Hypoxemic Neurological Damages in Neonates With Congenital Heart Defects?

Congenital heart defects (CHD), the most common cause of birth defects with increasing birth prevalence, affect nearly 1% of live births worldwide. Cyanotic CHD are characterized by hypoxemia, with subsequent reduced oxygen delivery to the brain, especially critical during brain development, beginning in the fetus and continuing through the neonatal period. Therefore, neonates with CHD carry a high risk for neurological comorbidities, even more frequently when there are associated underlying genetic disorders. We review the currently available knowledge on potential prevention strategies to reduce brain damage induced by hypoxemia during fetal development and immediately after birth, and the role of erythropoietin (EPO) as a potential adjunctive treatment. Maternal hyper-oxygenation had been studied as a potential therapeutic to improve fetal oxygenation. Despite demonstrating some effectiveness, maternal hyper-oxygenation has proven to be impractical for extensive clinical application, thus prompting the investigation of specific pathways for pharmacological intervention. Among those, the role of antioxidant pathways and Hypoxia Inducible Factors (HIF) have been studied for their involvement in the protective response to hypoxic injury. One of the proteins induced by HIF, EPO, has properties of being anti-apoptotic, antioxidant, and protective for neurons, astrocytes, and oligodendrocytes. In human trials, EPO administration in neonates with hypoxic ischemic encephalopathy (HIE) significantly reduced the neurological hypoxemic damages in several reported studies. Currently, it is unknown if the mechanisms of pathophysiology of cyanotic CHD are like HIE. Neonates with cyanotic CHD are exposed to both chronic hypoxemia and episodes of acute ischemia-reperfusion injury when undergo cardiopulmonary bypass surgery requiring aortic cross-clamp and general anesthesia. Our review supports future trials to evaluate the potential efficiency of EPO in reducing the hypoxemic neurologic damages in neonates with CHD. Furthermore, it suggests the need to identify early biomarkers of hypoxia-induced neurological damage, which must be sensitive to the neuroprotective effects of EPO.

Influence of Intrinsic Aerobic Exercise Capacity and Sex on Cardiac Injury Following Acute Myocardial Ischemia and Reperfusion.

Purpose: Previous reports have suggested that active exercise aside, intrinsic aerobic running capacity (Low = LCR, high = HCR) in otherwise sedentary animals may influence several cardiovascular health-related indicators. Relative to the HCR phenotype, the LCR phenotype is characterized by decreased endothelial reactivity, increased susceptibility to reperfusion-induced arrhythmias following short, non-infarction ischemia, and increased diet-induced insulin resistance. More broadly, the LCR phenotype has come to be characterized as a “disease prone” model, with the HCRs as “disease resistant.” Whether these effects extend to injury outcomes in an overt infarction or whether the effects are gender specific is not known. This study was designed to determine whether HCR/LCR phenotypic differences would be evident in injury responses to acute myocardial ischemia-reperfusion injury (AIR), measured as infarct size and to determine whether sex differences in infarction size were preserved with phenotypic selection.Methods: Regional myocardial AIR was induced in vivo by either 15 or 30 min ligation of the left anterior descending coronary artery, followed by 2 h of reperfusion. Global ischemia was induced in isolated hearts ex vivo using a Langendorff perfusion system and cessation of perfusion for either 15 or 30 min followed by 2 h of reperfusion. Infarct size was determined using 2, 3, 5–triphenyltetrazolium chloride (TTC) staining, and normalized to area at risk in the regional model, or whole heart in the global model. Portions of the tissue were paraffin embedded for H&E staining and histology analysis.Results: Phenotype dependent differences in infarct size were seen with 15 min occlusion/2 h reperfusion (LCR > HCR, p < 0.05) in both regional and global models. In both models, longer occlusion times (30 min/2 h) produced significantly larger infarctions in both phenotypes, but phenotypic differences were no longer present (LCR vs. HCR, p = n.s.). Sex differences in infarct size were present in each phenotype (LCR male > LCR female, p < 0.05; HCR male > HCR female, p < 0.05 regardless of length of occlusion, or ischemia model.Conclusions: There is cardioprotection afforded by high intrinsic aerobic capacity, but it is not infinite/continuous, and may be overcome with sufficient injury burden. Phenotypic selection based on endurance running capacity preserved sex differences in response to both short and longer term coronary occlusive challenges. Outcomes could not be associated with differences in system characteristics such as circulating inflammatory mediators or autonomic nervous system influences, as similar phenotypic injury patterns were seen in vivo, and in isolated crystalloid perfused heart ex vivo.

Hyperbaric oxygen therapy does not alleviate tourniquet-induced acute ischemia-reperfusion injury in mouse skeletal muscles

During tourniquet application, blood flow is restricted to a limb to stop excessive limb hemorrhage in a trauma setting and to create a bloodless operating field in the surgical setting. During tourniquet-related ischemia, aerobic respiration stops, and ATP is depleted, and during subsequent reperfusion, there is an increase in reactive oxygen species (ROS) production and other endogenous substances, which leads to acute ischemia-reperfusion (IR) injuries, including tissue necrosis and skeletal muscle contractile dysfunction. Hyperbaric oxygen (HBO) therapy can increase the arterial oxygen tension in the tissues of patients with general hypoxia/anoxia, including carbon monoxide poisoning, circulatory arrest, and cerebral and myocardial ischemia. Here, we studied the protective effects of HBO pretreatment with 100% oxygen at 2.5 ATA against tourniquet/IR injury in mice. After one hour of HBO therapy with 100% oxygen at 2.5 ATA was administered to C57/BL6 mice, a rubber band was placed at the hip joint of the unilateral hindlimb to induce 3 h of ischemia and then released for 48 h of reperfusion. We analyzed gastrocnemius muscle morphology and contractile function and measured the levels of ATP and ROS accumulation in the muscles. HBO pretreatment did not improve tourniquet/IR-injured gastrocnemius muscle morphology and muscle contraction. Tourniquet/IR mice with HBO pretreatment showed no increase in ATP levels in IR tissues, but they did have a decreased amount of ROS accumulation in the muscles, compared to IR mice with no HBO pretreatment. These data suggest that one hour of HBO pretreatment with 100% oxygen at 2.5 ATA increases the antioxidant response to lower ROS accumulation but does not increase ATP levels in IR muscles and improve tourniquet/IR-injured muscle morphology and contractile function.