Myocardial glutathione depletion impairs recovery of isolated blood-perfused hearts after global ischaemia

This study was performed to determine whether depletion of myocardial glutathione would impair recovery of left ventricular function of blood-perfused, isolated hearts after reversible ischaemic injury. Cats were treated with either vehicle or buthionine sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase, the rate-limiting enzyme in the synthesis of glutathione. The feline isolated hearts were perfused with the blood of normal donor cats before and after 40 min of global myocardial ischaemia. The myocardial concentration of glutathione of the BSO group, 178+/-38 ng/mg tissue, was significantly less than that of the control group, 292+/-38 ng/mg tissue (PP=0.05 vs. control). The peak left ventricular dP/dt after reperfusion, expressed as a fraction of the peak dP/dt before ischaemia, was 1.08+/-0.14 for the control group and 0.78+/-0.09 for the BSO group (P=0.05 vs. control). The myocardial creatine kinase activity of the BSO group, 1046+/-46 U/g tissue, was not significantly different from that of the control group, 1038+/-17 U/g tissue (P=0.87). Thus, depletion of myocardial glutathione resulted in impaired post-ischaemic contractile function that cannot be attributed to a greater extent of irreversible cell injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29775/1/0000114.pd

Mechanism of Preconditioning by Isoflurane in Rabbits: A Direct Role for Reactive Oxygen Species

LARGE quantities of reactive oxygen species (ROS) released during reperfusion after coronary artery occlusion damage proteins responsible for intracellular homeostasis, produce tissue injury, depress contractile function, and increase myocardial infarct size. In contrast, small quantities of ROS may exert beneficial effects during ischemia and reperfusion when released before a prolonged ischemic event. ROS derived from mitochondria during a brief ischemic episode produce preconditioning. Free radical scavengers administered during ischemic preconditioning (IPC) markedly attenuate the protective effect of the preconditioning stimulus on infarct size. These data suggest that IPC is mediated in part by small quantities of ROS released during preconditioning. Volatile anesthetics protect myocardium against infarction through a signal transduction pathway that includes adenosine type 1 receptors, protein kinase C, inhibitory guanine regulatory proteins, and mitochondrial and sarcolemmal adenosine triphosphate-regulated potassium (KATP) channels. A recent investigation by Müllenheim et al . provides compelling evidence that ROS also mediate myocardial protection produced by volatile anesthetics. We sought to confirm and extend these important results by examining the hypothesis that ROS scavengers inhibit isoflurane-induced protection against irreversible ischemic injury. We further tested the hypothesis that isoflurane directly generates ROS in rabbit ventricular myocardium in vivo using a confocal microscopic technique combined with the superoxide anion-specific fluorescent probe dihydroethidium

Cardioprotective Effects of Glycyrrhizic Acid Against Isoproterenol-Induced Myocardial Ischemia in Rats

The aim of the present study was to look into the possible protective effects of glycyrrhizic acid (GA) against isoproterenol-induced acute myocardial infarction in Sprague-Dawley rats. The effect of three doses of glycyrrhizic acid in response to isoproterenol (ISO)-induced changes in 8-isoprostane, lipid hydroperoxides, super oxide dismutase and total glutathione were evaluated. Male Sprague-Dawley rats were divided into control, ISO-control, glycyrrhizic acid alone (in three doses-5, 10 and 20 mg/kg BW) and ISO with glycyrrhizic acid (in three doses) groups. ISO was administered at 85 mg/kg BW at two consecutive days and glycyrrhizic acid was administered intraperitoneally for 14 days. There was a significant increase in 8-isoprostane (IP) and lipid hydroperoxide (LPO) level in ISO-control group. A significant decrease in total superoxide dismutase (SOD) and total glutathione (GSH) was seen with ISO-induced acute myocardial infarction. Treatment with GA significantly increased SOD and GSH levels and decreased myocardial LPO and IP levels. Histopathologically, severe myocardial necrosis and nuclear pyknosis and hypertrophy were seen in ISO-control group, which was significantly reduced with GA treatment. Gycyrrhizic acid treatment proved to be effective against isoproterenol-induced acute myocardial infarction in rats and GA acts as a powerful antioxidant and reduces the myocardial lipid hydroperoxide and 8-isoprostane level

Combined antioxidant formulation of ascorbic acid with resveratrol ameliorates isoproterenol-induced myocardial infarction in rats

The current investigation was proposed to assess the effectiveness of the combination of resveratrol and ascorbic acid against Isoproterenol (ISO)-induced myocardial infarction in rats. The experimental model was divided into six groups (n = 6 in each group). Group I: control, Group 2: isoproterenol (ISO)-100 mg/kg b.wt, Group 3: ISO+Resveratrol (RES) (20 mg/kg b.wt) treated, Group 4: ISO+ Ascorbic acid (AA) (80 mg/kg b.wt) treated, Group 5: ISO+RES (20 mg/kg b.wt)+AA (80 mg/kg b.wt) treated and Group 6: RES (20 mg/kg b.wt)+ AA (80 mg/kg b.wt) alone treated. The study showed an increase in lipid peroxides and cardiac markers in the serum samples of experimental animals administered with ISO. Treatment with RES and AA individually and a combinational formulation brought a significant decrease in lipid peroxides and cardiac markers. They increased the level of enzymatic antioxidants and non-enzymatic antioxidant levels. Histopathological results showed the distortion of heart architecture among the experimental groups administered with ISO and significant recovery when treated with RES and AA individually and in their combination. The study presents the effective combination of RES and AA in combating ISO-induced myocardial infarction and protection against ROS-mediated oxidative stress

Effects of a novel inhibitor of lipid peroxidation on injury caused by oxidative stress and ischemia-reperfusion

Introduction. Coronary artery disease with an eventual coronary occlusion and subsequent myocardial injury is one of the leading causes of death in the world. Besides spontaneous reperfusion of an occluded artery thrombolysis and percutaneous transluminal coronary angioplasty (PTCA)are two procedures performed widely, that aim for the restoration of blood flow, i.e. also result in reperfusion. Reperfusion may increase injury over and above that sustained during ischemia. One of the suggested mechanisms of so-called reperfusion injury is the generation and action of reactive oxygen species (ROS). Although in clinical conditions timely reperfusion of the ischemic area is the cornerstone of treatment, there is a possible role of antioxidant therapy to limit ischemia-reperfusion injury. Aims. I. To investigate the protective efficacy of H290/51, a low molecular weight, hydrophilic compound with effects similar to Vitamin E and inhibiting lipid peroxidation, on hypoxia-reoxygenation injury of isolated cardiomyocytes. II. To study the effect of H290/51 on oxidative injury induced by exogenous ROS in isolated, perfused rat hearts. III. To examine its effect on ultrastructural changes in isolated rat hearts subjected to ischemia and reperfusion. IV. To assess the effect of inhibiting lipid peroxidation on functional and biochemical injury caused by global, normothermic ischemia-reperfusion in isolated rat hearts. Methods. I. Neonatal myocytes were cultured. On day 6 cells were rendered hypoxic for 1 hour followed by 4 hours of reoxygenation. Lactate dehydrogenase (LDH) leakage was assessed. II. Oxidative injury was induced in isolated rat hearts by perfusion with H2O2 for 10 min, followed by 50 minutes of recovery. Functional (heart rate [HR], coronary flow [CF], left ventricular end-diastolic pressure [LVEDP], left ventricular developed pressure [LVDP]) and biochemical ([LDH leakage], thiobarbituric acid parameters were measured. III. Isolated rat hearts were subjected to 30 minutes of global, normothermic ischemia, followed by 20 minutes of reperfusion. Hearts were sampled for electron microscopy. Quantitative stereological morphometry was employed. IV. Isolated rat hearts were subjected to 30 minutes of global, normothermic ischemia, followed by reperfusion for 20 minutes. Functional (HR, CF, LVDP, LVEDP) and biochemical (LDH leakage, TBARS) parameters were measured. Materials. A novel low molecular weight indenoindole derivative, H290/51 (cis-5, 5a, 6,10,b-tetrahydro-9-methoxy-7-methylindeno [2,1-b]indole) was selected as the antioxidant in the experiments. The compound is an inhibitor of lipid peroxidation, with balanced hydro- and lipophilicity, thus it can rapidly penetrate cell membranes to intracellular sites of ROS generation, lipid peroxidation and oxidant injury. Results. I. H290/51 inhibited LDH leakage in isolated cardiomyocytes induced by hypoxia-reoxygenation in a dose-dependent manner. II. H290/51 attenuated diastolic dysfunction as it inhibited the increase in LVEDP caused by H2O2. The protective effect was further evidenced by the inhibition of both LDH release and accumulation of TBARS after H2O2 exposure. III. Ischemia-induced increase in interstitial volume and in volume fractions of myocytes and interstitium was inhibited by H290/51. The difference was already present at the end of ischemia, but disappeared during reperfusion. IV. Ischemia caused an increase in LVEDP and decrease in LVDP and CF, and induced malignant arrhythmias. H290/51 effectively inhibited these changes if it was administered throughout the experiment including the stabilization period before ischemia, but was less potent when given only during reperfusion. Conclusion. Our study indicates that inhibiting lipid peroxidation by H290/51 counteracts several deleterious processes in an experimental myocardial ischemia/reperfusion injury model. Our data indicate that to some extent its antioxidant properties may be effective not only during reperfusion, but already during ischemia. Thus, a better preserved functional and morphological status of the myocardium during ischemia may yield a better capacity to survive reperfusion injury. The chemical properties of the compound, most importantly its balanced hydro- and lipophilicity and its small molecular weight result in its ability to rapidly reach the intracellular sites where induced free radicals are produced. Clinically, such properties might be of therapeutic value, and H290/51 may therefore be a promising candidate for clinical evaluation and further study

Theranostic Copolymers Neutralize Reactive Oxygen Species and Lipid Peroxidation Products for the Combined Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) results in the generation of reactive oxygen species (ROS) and lipid peroxidation product (LPOx), including acrolein and 4-hydroxynonenal (4HNE). The presence of these biochemical derangements results in neurodegeneration during the secondary phase of the injury. The ability to rapidly neutralize multiple species could significantly improve outcomes for TBI patients. However, the difficulty in creating therapies that target multiple biochemical derangements simultaneously has greatly limited therapeutic efficacy. Therefore, our goal was to design a material that could rapidly bind and neutralize both ROS and LPOx following TBI. To do this, a series of thiol-functionalized biocompatible copolymers based on lipoic acid methacrylate and polyethylene glycol monomethyl ether methacrylate (FW ∼950 Da) (O950) were prepared. A polymerizable gadolinium-DOTA methacrylate monomer (Gd-MA) was also synthesized starting from cyclen to facilitate direct magnetic resonance imaging and in vivo tracking of accumulation. These neuroprotective copolymers (NPCs) were shown to rapidly and effectively neutralize both ROS and LPOx. Horseradish peroxidase absorbance assays showed that the NPCs efficiently neutralized H2O2, while R-phycoerythrin protection assays demonstrated their ability to protect the fluorescent protein from oxidative damage. 1H NMR studies indicated that the thiol-functional NPCs rapidly form covalent bonds with acrolein, efficiently removing it from solution. In vitro cell studies with SH-SY5Y-differentiated neurons showed that NPCs provide unique protection against toxic concentrations of both H2O2and acrolein. NPCs rapidly accumulate and are retained in the injured brain in controlled cortical impact mice and reduce post-traumatic oxidative stress. Therefore, these materials show promise for improved target engagement of multiple biochemical derangements in hopes of improving TBI therapeutic outcomes

Effect of N-acetylcysteine ​​and therapeutic hypothermia on ischemia-reperfusion injury after experimental cardiac arrest

Terapeutická hypotermie (TH) je doposud jedinou klinicky využívanou intervencí, která působí tlumivě prakticky na všechny projevy ischemicko-reperfuzního poškození po srdeční zástavě. V experimentálních modelech zabývajících se danou problematikou byl mnohokrát prokázán pozitivní vliv exogenních antioxidantů na průběh ischemicko-reperfuzního poškození a jeho prevenci. Naším cílem bylo na prasečím modelu posoudit, zda vysoké dávky intravenózního N-acetylcysteinu (NAC) povedou k redukci ischemicko-reperfuzní poškození po experimentální srdeční zástavě jak v monoterapii, tak v kombinaci s TH. Zvířata byla randomizačně rozdělena do 5 skupin: aplikace NAC a TH (skupina A), aplikace NAC během srdeční zástavy (skupina B), navození TH (skupina C), bez intervence (skupina D) a aplikace NAC po obnově spontánní cirkulace (skupina E). V této práci se nám nepodařilo prokázat aditivní efekt NAC v kombinaci s TH. Aplikace NAC během srdeční zástavy vedla ke statisticky významnému snížení oxidativního stresu, avšak zároveň vlivem anafylaktické reakce vedla k vysoké úmrtnosti ve skupině B a ke změnám v hemodynamických parametrech u skupiny E. Klíčová slova: Terapeutická hypotermie, srdeční zástava, N-acetylcystein, ischemicko-reperfuzní poškození, kardiopulmonální resuscitace, oxidativní stres, kyslíkové radikályTherapeutic hypothermia (TH) is the only clinically used intervention that suppresses nearly all manifestations of ischemia-reperfusion injury after cardiac arrest. Experimental models has proven that exogenous antioxidants have positive impact on ischemia-reperfusion injury and it is able to prevent it as well. Results in this thesis are based on application of high dosages of N-acetylcystein (NAC) on ischemia-reperfusion injury after experimental cardiac arrest in a porcine model. It was used as a form of monoteraphy or in combination with TH. During the experiment animals were randomized into 5 groups: administration of NAC and TH (group A), administration of NAC during cardiac arrest (group B), induction of TH (group C), without any intervention (group D) and administration of NAC after return of spontaneous circulation (group E). We were not able to confirm additive effect of NAC in combination with TH. Administration of NAC during cardiac arrest led to statistically important reduction of oxidative stress but in the same time anafylactic reaction led to higher mortality in group B and changes in hemodynamical parameters in group E. Key words: Therapeutic hypothermia, cardiac arrest, N-acetylcysteine, ischemia-reperfusion injury, cardiopulmonary resuscitation, oxidative stress, oxygen radicalsKatedra fyziologieDepartment of PhysiologyPřírodovědecká fakultaFaculty of Scienc