Abstract P133: Role of Akt and p38 in Oxidant Stress Injury and Hypothermic Protection in Murine Cardiomyocytes

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Kimberly R Wojcik ◽  
Zuo-Hui Shao ◽  
Chang-Qing Li ◽  
Kimm J Hamann ◽  
Terry L Vanden Hoek
Keyword(s):  
Cell Death ◽  
Cardiac Arrest ◽  
Cell Injury ◽  
Ischemia Reperfusion ◽  
Oxidant Stress ◽  
Ros Generation ◽  
Akt Inhibitor ◽  
Stress Injury ◽  
P38 Inhibitor ◽  
Sb 203580

Cardiac arrest is an ischemia/reperfusion (I/R) disease characterized by oxidant generation, inflammation, and cell death; and hypothermia (HT) has been shown to improve post-cardiac arrest reperfusion injury. We developed a neonatal mouse cardiomyocyte model of I/R (90 min I + 3 hr R) that demonstrates cell injury associated with increased reactive oxygen species (ROS) generation at reperfusion (as measured by DCFH). Mild HT (32°C) protects mouse cardiomyocytes from I/R injury, and we hypothesize that this protection may be related to the activation of the survival kinase Akt. The Akt inhibitor API-2 (10 ìM) reversed HT protection [32.4 ± 7.1% vs 65.7 ± 6.3% with API-2, p< .01(as measured by PI)] to cell death levels commensurate with normothermic I/R injury (60.7 ± 6.0%). Phospho-Akt (pAkt) levels declined during ischemia, and while both Ser473 and Thr308 were phosphorylated in normothermia and HT within 15 min reperfusion, HT showed an augmented level of pAkt at Thr308. Furthermore, this increase was sustained for the first 30 min of reperfusion. To further study this relationship, murine cardiomyocytes were exposed to exogenous H2O2 to mimic the oxidant stress associated with I/R. Mouse cardiomyocytes demonstrated a dose- and time-dependent activation of Akt to H2O2 that showed maximal activation of both the Ser473 and Thr308 sites within 30 min with 200 ìM H2O2. As in I/R-stimulated cells, the Thr308 site declined to near baseline levels within 1 hr while Ser473 remained elevated. Based on recent findings linking Akt and ROS with p38, we examined the effect of I/R and H2O2 on p38. Mouse cardiomyocytes demonstrated a rapid activation of p-p38 (Thr10/Tyr182) in the context of both stresses. Further, we studied the effect of the Akt inhibitor, API-2, as well as the p38 inhibitor, SB 203580, in H2O2-stimulated cells. As in I/R, API-2 blocked H2O2-induced pAkt, but this inhibitor did not have any effect on p-p38. However, when p38 activation was blocked using SB 203580, pAkt levels decreased by 2 hr. These data suggest that HT is, in part, mediated through Akt and that p38 lies upstream of Akt in the context of oxidant stress. These kinases may act as triggers for the initiation of survival pathways in cardiomyocytes to combat potential damage induced by ROS generation.

Baicalein attenuates oxidant stress in cardiomyocytes

2002 ◽  
Vol 282 (3) ◽  
pp. H999-H1006 ◽  
Author(s):  
Zuo-Hui Shao ◽  
Terry L. Vanden Hoek ◽  
Yimin Qin ◽  
Lance B. Becker ◽  
Paul T. Schumacker ◽  
...  
Keyword(s):  
Cell Death ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Ischemia Reperfusion ◽  
Oxidant Stress ◽  
Complex Iii ◽  
Ros Generation ◽  
Resonance Spectroscopy ◽  
Iodide Uptake ◽  
Simulated Ischemia

Flavonoids within Scutellaria baicalensis may be potent antioxidants on the basis of our studies of S. baicalensis extract. To further this work, we studied the antioxidative effects of baicalein, a flavonoid component of S. baicalensis, in a chick cardiomyocyte model of reactive oxygen species (ROS) generation during hypoxia, simulated ischemia-reperfusion, or mitochondrial complex III inhibition with antimycin A. Oxidant stress was measured by oxidation of the intracellular probes 2′,7′-dichlorofluorescin diacetate and dihydroethidium. Viability was assessed by propidium iodide uptake. Baicalein attenuated oxidant stress during all conditions studied and acted within minutes of treatment. For example, baicalein given only at reperfusion dose dependently attenuated the ROS burst at 5 min after 1 h of simulated ischemia. It also decreased subsequent cell death at 3 h of reperfusion from 52.3 ± 2.5% in untreated cells to 29.4 ± 3.0% (with return of contractions; P < 0.001). In vitro studies using electron paramagnetic resonance spectroscopy with the spin trap 5-methoxycarbonyl-5-methyl-1-pyrroline- N-oxide revealed that baicalein scavenges superoxide but does not mimic the effects of superoxide dismutase. We conclude that baicalein can scavenge ROS generation in cardiomyocytes and that it protects against cell death in an ischemia-reperfusion model when given only at reperfusion.

scholarly journals miR-181c-5p Exacerbates Hypoxia/Reoxygenation-Induced Cardiomyocyte Apoptosis via Targeting PTPN4

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Liang Ge ◽  
Yin Cai ◽  
Fan Ying ◽  
Hao Liu ◽  
Dengwen Zhang ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Apoptosis ◽  
Cell Injury ◽  
Apoptotic Cell ◽  
Ischemia Reperfusion ◽  
Control Cell ◽  
Luciferase Reporter ◽  
Apoptosis Pathway ◽  
H9c2 Cardiomyocytes ◽  
Hypoxia Reoxygenation

Background. Activation of cell apoptosis is a major form of cell death during myocardial ischemia/reperfusion injury (I/RI). Therefore, examining ways to control cell apoptosis has important clinical significance for improving postischemic recovery. Clinical evidence demonstrated that miR-181c-5p was significantly upregulated in the early phase of myocardial infarction. However, whether or not miR-181c-5p mediates cardiac I/RI through cell apoptosis pathway is unknown. Thus, the present study is aimed at investigating the role and the possible mechanism of miR-181c-5p in apoptosis during I/R injury by using H9C2 cardiomyocytes. Methods and Results. The rat origin H9C2 cardiomyocytes were subjected to hypoxia/reoxygenation (H/R, 6 hours hypoxia followed by 6 hours reoxygenation) to induce cell injury. The results showed that H/R significantly increased the expression of miR-181c-5p but not miR-181c-3p in H9C2 cells. In line with this, in an in vivo rat cardiac I/RI model, miR-181c-5p expression was also significantly increased. The overexpression of miR-181c-5p by its agomir transfection significantly aggravated H/R-induced cell injury (increased lactate dehydrogenase level and reduced cell viability) and exacerbated H/R-induced cell apoptosis (greater cleaved caspases 3 expression, Bax/Bcl-2 and more TUNEL-positive cells). In contrast, inhibition of miR-181c-5p in vitro had the opposite effect. By using computational prediction algorithms, protein tyrosine phosphatase nonreceptor type 4 (PTPN4) was predicted as a potential target gene of miR-181c-5p and was verified by the luciferase reporter assay. The overexpression of miR-181c-5p significantly attenuated the mRNA and protein expression of PTPN4 in H9C2 cardiomyocytes. Moreover, knockdown of PTPN4 significantly aggravated H/R-induced enhancement of LDH level, cleaved caspase 3 expression, and apoptotic cell death, which mimicked the proapoptotic effects of miR-181c-5p in H9C2 cardiomyocytes. Conclusions. These findings suggested that miR-181c-5p exacerbates H/R-induced cardiomyocyte injury and apoptosis via targeting PTPN4 and that miR-181c-5p/PTPN4 signaling may yield novel strategies to combat myocardial I/R injury.

scholarly journals Cell death during ischemia: relationship to mitochondrial depolarization and ROS generation

2003 ◽  
Vol 284 (2) ◽  
pp. H549-H558 ◽  
Author(s):  
Jacques Levraut ◽  
Hirotaro Iwase ◽  
Z.-H. Shao ◽  
Terry L. Vanden Hoek ◽  
Paul T. Schumacker
Keyword(s):  
Cell Death ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Permeability Transition ◽  
Ros Generation ◽  
Ischemia And Reperfusion ◽  
Mitochondrial Depolarization ◽  
Sytox Green ◽  
Transport Chain

Ischemia-reperfusion injury induces cell death, but the responsible mechanisms are not understood. This study examined mitochondrial depolarization and cell death during ischemia and reperfusion. Contracting cardiomyocytes were subjected to 60-min ischemia followed by 3-h reperfusion. Mitochondrial membrane potential (ΔΨm) was assessed with tetramethylrhodamine methyl ester. During ischemia, ΔΨm decreased to 24 ± 5.5% of baseline, but no recovery was evident during reperfusion. Cell death assessed by Sytox Green was minimal during ischemia but averaged 66 ± 7% after 3-h reperfusion. Cyclosporin A, an inhibitor of mitochondrial permeability transition, was not protective. However, pharmacological antioxidants attenuated the fall in ΔΨm during ischemia and cell death after reperfusion and decreased lipid peroxidation as assessed with C11-BODIPY. Cell death was also attenuated when residual O2 was scavenged from the perfusate, creating anoxic ischemia. These results suggested that reactive oxygen species (ROS) were important for the decrease in ΔΨm during ischemia. Finally, 143B-ρ0 osteosarcoma cells lacking a mitochondrial electron transport chain failed to demonstrate a depletion of ΔΨm during ischemia and were significantly protected against cell death during reperfusion. Collectively, these studies identify a central role for mitochondrial ROS generation during ischemia in the mitochondrial depolarization and subsequent cell death induced by ischemia and reperfusion in this model.

H2O2-Responsive Antioxidant Nanoparticle Attenuates Whole Body Ischemia/Reperfusion-Induced Multi-Organ Damages

2020 ◽  
pp. 107424842096957
Author(s):  
Ruijian Li ◽  
Sang Jae Rhee ◽  
Soochan Bae ◽  
Shi Su ◽  
Chang-Sun Kang ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiac Arrest ◽  
Ischemia Reperfusion ◽  
Spontaneous Circulation ◽  
Organ Injury ◽  
Whole Body ◽  
Ros Generation ◽  
Vanillyl Alcohol ◽  
Multiple Organs ◽  
Significant Difference

Mortality and morbidity after cardiac arrest remain high due to ischemia/reperfusion (I/R) injury causing multi-organ damages, even after successful return of spontaneous circulation. We previously generated H2O2-activatable antioxidant nanoparticles formulated with copolyoxalate containing vanillyl alcohol (PVAX) to prevent I/R injury. In this study, we examined whether PVAX could effectively reduce organ damages in a rat model of whole-body ischemia/reperfusion injury (WBIR). To induce a cardiac arrest, 70µl/100 g body weight of 1 mmol/l potassium chloride was administered via the jugular venous catheter. The animals in both the vehicle and PVAX-treated groups had similar baseline blood pressure. After 5.5 minutes of cardiac arrest, animals were resuscitated via intravenous epinephrine followed by chest compressions. PVAX or vehicle was injected after the spontaneous recovery of blood pressure was noted, followed by the same dose of second injection 10 minutes later. After 24 hours, multiple organs were harvested for pathological, biochemical, molecular analyses. No significant difference on the restoration of spontaneous circulation was observed between vehicle and PVAX groups. Analysis of organs harvested 24 hours post procedure showed that whole body I/R significantly increased reactive oxygen species (ROS) generation, inflammatory markers, and apoptosis in multiple organs (heart, brain, and kidney). PVAX treatment effectively blocked ROS generation, reduced the elevation of pro-inflammatory cytokines, and decreased apoptosis in these organs. Taken together, our results suggest that PVAX has potent protective effect against WBIR induced multi-organ injury, possibly by blocking ROS-mediated cell damage.

Abstract 217: Increased Oxidation of Amplex Red in Post-Cardiac Arrest Human and Rat Plasma Can Be Utilized as a Potential Marker of Injury Severity

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Muhammad Shoaib ◽  
Ann Iverson ◽  
Tai Yin ◽  
Lance B Becker ◽  
Junhwan KIM
Keyword(s):  
Hydrogen Peroxide ◽  
Cardiac Arrest ◽  
Injury Severity ◽  
Ischemia Reperfusion ◽  
University Hospital ◽  
Ros Generation ◽  
Ischemic Damage ◽  
Sprague Dawley ◽  
Amplex Red ◽  
Potential Marker

Introduction: Cardiac arrest (CA), an unexpected loss of appropriate electrical signaling in the heart, leads to a loss of blood circulation and decreased oxygen perfusion. Ischemia results in the generation of hydrogen peroxide and other reactive oxygen species (ROS), thereby causing damage to tissues. Currently, there are no available biomarkers to elucidate the severity of ischemic damage. Therefore, oxidation of the Amplex Red (AR) assay by ROS into its fluorescent product, resorufin, may be used as a marker to determine injury severity. Methods: Plasma isolated from human CA patients from North Shore University Hospital was obtained to determine ROS generation. A commercially available Amplex Red assay kit was used to measure the amount of resorufin produced after oxidation due to hydrogen peroxide, peroxynitrite, and other ROS. To verify our human findings, we arbitrarily assigned adult male Sprague-Dawley rats into three groups (control, 10 min cardiac arrest, and 20 min cardiac arrest) using our reliable asphyxia-induced cardiac arrest model. Results: Despite human variations, our data on human CA patients showed an increased amount of AR oxidation as a result of ischemia. Our 10 min CA rat experimental model verified that Amplex Red is capable of detecting hydrogen peroxide and peroxynitrite formation after ischemia. Rats with 20 mins of ischemia time also produced resorufin, confirming that ischemia induces AR oxidation. Removing horseradish peroxidase and adding catalase controls for hydrogen peroxide and peroxynitrite, which should decrease AR oxidation; however, we observed an increase in AR oxidation. Therefore, we added phenylmethyl sulfonyl acid (PMSF), an inhibitor of carboxylesterase, an enzyme also capable of oxidizing Amplex Red, which resulted in decreased AR oxidation. Conclusion: By accounting for peroxide and peroxynitrite species, the increase in Amplex Red oxidation in the plasma of cardiac arrest human patients and rats can be attributed to carboxylesterase activity. Our data corroborates the various mechanisms of AR oxidation in the setting of ischemia-reperfusion allowing the Amplex Red assay to be utilized as a potential tool for assessing the degree of ischemic damage resulting from cardiac arrest.

scholarly journals Mitochondrial oxidant stress triggers cell death in simulated ischemia–reperfusion

2011 ◽  
Vol 1813 (7) ◽  
pp. 1382-1394 ◽  
Author(s):  
Gabriel Loor ◽  
Jyothisri Kondapalli ◽  
Hirotaro Iwase ◽  
Navdeep S. Chandel ◽  
Gregory B. Waypa ◽  
...  
Keyword(s):  
Cell Death ◽  
Ischemia Reperfusion ◽  
Oxidant Stress ◽  
Simulated Ischemia

scholarly journals PK11195 Protects From Cell Death Only When Applied During Reperfusion: Succinate-Mediated Mechanism of Action

2021 ◽  
Vol 12 ◽  
Author(s):  
Lea K. Seidlmayer ◽  
Benjamin J. Hanson ◽  
Phung N. Thai ◽  
Saul Schaefer ◽  
Donald M. Bers ◽  
...  
Keyword(s):  
Cell Death ◽  
Large Scale ◽  
Ventricular Myocytes ◽  
Ischemia Reperfusion ◽  
Cardiac Injury ◽  
Translocator Protein ◽  
Initial Increase ◽  
Acute Ischemia ◽  
Ros Generation ◽  
Fluorescent Indicators

Aim: Reperfusion after myocardial ischemia causes cellular injury, in part due to changes in mitochondrial Ca2+ handling, oxidative stress, and myocyte energetics. We have previously shown that the 18-kDa translocator protein of the outer mitochondrial membrane (TSPO) can modulate Ca2+ handling. Here, we aim to evaluate the role of the TSPO in ischemia/reperfusion (I/R) injury.Methods: Rabbit ventricular myocytes underwent simulated acute ischemia (20 min) and reperfusion (at 15 min, 1 h, and 3 h) in the absence and presence of 50 μM PK11195, a TSPO inhibitor. Cell death was measured by lactate dehydrogenase (LDH) assay, while changes in mitochondrial Ca2+, membrane potential (ΔΨm), and reactive oxygen species (ROS) generation were monitored using confocal microscopy in combination with fluorescent indicators. Substrate utilization was measured with Biolog mitochondrial plates.Results: Cell death was increased by ~200% following I/R compared to control untreated ventricular myocytes. Incubation with 50 μM PK11195 during both ischemia and reperfusion did not reduce cell death but increased mitochondrial Ca2+ uptake and ROS generation. However, application of 50 μM PK11195 only at the onset and during reperfusion effectively protected against cell death. The large-scale oscillations in ΔΨm observed after ~1 h of reperfusion were significantly delayed by 1 μM cyclosporin A and almost completely prevented by 50 μM PK11195 applied during 3 h of reperfusion. After an initial increase, mitochondrial Ca2+, measured with Myticam, rapidly declined during 3 h of reperfusion after the initial transient increase. This decline was prevented by application of PK11195 at the onset and during reperfusion. PK11195 prevented a significant increase in succinate utilization following I/R and succinate-induced forward-mode ROS generation. Treatment with PK11195 was also associated with a significant increase in glutamate and a decrease in leucine utilization.Conclusion: PK11195 administered specifically at the moment of reperfusion limited ROS-induced ROS release and cell death, likely in part, by a shift from succinate to glutamate utilization. These data demonstrate a unique mechanism to limit cardiac injury after I/R.

scholarly journals Mechanisms of cell death in oxidant stress and ischemia‐reperfusion injury

2007 ◽  
Vol 21 (5) ◽  
Author(s):  
Gabriel Loor ◽  
Jyothi Kondapalli ◽  
Bumihka Sharma ◽  
Robert Guzy ◽  
Paul Schumacker
Keyword(s):  
Cell Death ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Oxidant Stress

Mechanisms of Liver Injury. II. Mechanisms of neutrophil-induced liver cell injury during hepatic ischemia-reperfusion and other acute inflammatory conditions

2006 ◽  
Vol 290 (6) ◽  
pp. G1083-G1088 ◽  
Author(s):  
Hartmut Jaeschke
Keyword(s):  
Inflammatory Response ◽  
Cell Injury ◽  
Hypochlorous Acid ◽  
Tissue Injury ◽  
Ischemia Reperfusion ◽  
Oxidant Stress ◽  
Reactive Oxygen ◽  
Target Cells ◽  
Proinflammatory Mediators ◽  
Antioxidant Defense Systems

Polymorphonuclear leukocytes (neutrophils) are a vital part of the innate immune response to microbial infections and tissue trauma, e.g., ischemia-reperfusion injury, in many organs including the liver. However, an excessive inflammatory response can lead to a dramatic aggravation of the existing injury. To design interventions, which selectively target the detrimental effects of neutrophils, a detailed understanding of the pathophysiology is critical. Systemic or local exposure to proinflammatory mediators causes activation and priming of neutrophils for reactive oxygen formation and recruits them into the vascular beds of the liver without causing tissue injury. However, generation of a chemotactic signal from the parenchyma will trigger extravasation and an attack on target cells (e.g., hepatocytes). Adhesion to the target induces degranulation with release of proteases and formation of reactive oxygen species including hydrogen peroxide and hypochlorous acid, which can diffuse into hepatocytes and induce an intracellular oxidant stress and mitochondrial dysfunction. Various neutrophil-derived proteases are involved in transmigration and cell toxicity but can also promote the inflammatory response by processing of proinflammatory mediators. In addition, necrotic cells release mediators, e.g., high-mobility group box-1, which further promotes neutrophilic hepatitis and tissue damage. On the basis of these evolving insights into the mechanisms of neutrophil-mediated liver damage, the most selective strategies appear not to interfere with the cytotoxic potential of neutrophils, but rather strengthen the target cells' defense mechanisms including enhancement of the intracellular antioxidant defense systems, activation of cell survival pathways, or initiation of cell cycle activation and regeneration.

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