Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have used a new technique for extraction of myocardial membranes (0.25 M sucrose, 0.6 M KCl) to isolate particulate and soluble proteins and enzymatic activities in an effort to quantify changes characteristic of progressive ischemia. Myocardial blood flow (MBF) was measured with microspheres (15 micrometer diameter) in all samples of tissue used for assay of proteins and enzymatic activities; MBF to the moderately ischemic areas (M-ischemia) was 53% of control (H-control); MBF to the severely ischemic areas (L-ischemia) was 9% of control. Significant decreases (P less than 0.001) in content of protein were seen in all post 1,000 g pellets and supernatant fluids in the L-ischemia zones; particulate lysosomal enzymatic activity was significantly decreased (P less than 0.001) in all four post 1,000 g pellets (2,500 g to 140,000 g) of the L-ischemic areas (for N-acetyl-beta-glucosaminidase and beta-glucuronidase). The increase in percent free activity of lysosomal enzymes (index of loss of latency) also was highly significant (P less than 0.001) in all particulate fractions of the L-ischemic areas. In addition, about 45% of the total activity of the microsomal marker enzyme, rotenone-insensitive NADH cytochrome C reductase (RINCR), was found in the 140,000 g pellet of H-control tissue (9.9 micronmol/min per g); this activity fell to 8.1 micronmol/min per g in M-ischemic areas (P less than 0.001) and to 5.3 micronmol/min per g in L-ischemic areas (P less than 0.001). This study demonstrates that changes in myocardial proteins, lysosomes, and other membrane-bound enzymes (RINCR) may provide reproducible bichemical parameters for assessing ischemic myocardial injury.
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PMID:Effects of well-defined ischemia on myocardial lysosomal and microsomal enzymes in a canine model. 21 2

We have previously shown that the polyethylene glycol conjugated superoxide dismutase (SOD), which has a plasma half-life of more than 24 h, protects the blood perfused rabbit heart against injury during ischaemia and reperfusion. However, the profile for the dose-dependency of protection was bell-shaped with loss of efficacy below 6000 and above 30,000 U/kg. In the present study, isolated rabbit hearts, perfused with blood from support rabbits, were subjected to a 2 min infusion with St Thomas' Hospital cardioplegic solution followed by 60 min of global ischaemia (37 degrees C) and 60 min of reperfusion. PEG-SOD was administered 1 h or 12-24 h before ischaemia. We assessed the effect of PEG-SOD on ischaemia- and reperfusion-induced changes in: (i) the tissue content of reduced glutathione (GSH), oxidized glutathione (GSSG) and malondialdehyde (MDA) and (ii) the activity of CuZn-SOD, Mn-SOD and glutathione peroxidase and reductase (GPD and GRD). Ischaemia and reperfusion reduced tissue GSH content by 70% and increased GSSG content by 400% (from their fresh aerobic values of 13.1.9 and 0.09 +/- 0.01 nmol/mg protein, respectively). PEG-SOD, given intravenously at various doses to donor and support rabbits 1 h or 12-24 h before ischaemia, protected against these changes with a bell-shaped dose-response relationship. Thus, with 0, 3000, 6000, 12,000, 30,000 and 60,000 U/kg, GSH content was 4.1 +/- 0.4, 4.8 +/- 0.4, 8.5 +/- 0.5, 12.3 +/- 1.6, 12.3 +/- 1.6 and 5.0 +/- 0.5 nmol/mg protein in the 1 h pretreatment group and 4.1 +/- 0.4, 4.2 +/- 0.5, 10.4 +/- 1.5, 11.2 +/- 1.1, 11.4 +/- 0.7 and 4.7 +/- 0.6 nmol/mg protein in the 12-24 h pretreatment group (means +/- S.E.M.). For GSSG the corresponding values were 0.36 +/- 0.04, 0.34 +/- 0.03, 0.12 +/- 0.01, 0.12 +/- 0.01, 0.11 +/- 0.01 and 0.41 +/- 0.03 nmol/mg protein for the 1 h group and 0.36 +/- 0.04, 0.35 +/- 0.02, 0.15 +/- 0.01, 0.12 +/- 0.01, 0.11 +/- 0.01 and 0.34 +/- 0.02 nmol/mg protein for the 12-24 h group. Ischaemia and reperfusion had no effect on tissue MDA content or CuZn-SOD, GDP and GRD activity, and in general, PEG-SOD also lacked significant effect on any of these variables at any dose studied. However, Mn-SOD activity was severely reduced by ischaemia and reperfusion (from 42 +/- 7 U/mg protein in fresh aerobic controls to 6 +/- 1 U/mg protein at the end of reperfusion).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:PEG-SOD and myocardial antioxidant status during ischaemia and reperfusion: dose-response studies in the isolated blood perfused rabbit heart. 143 18

Liver injury by 30-min ischemia following reperfusion was examined biochemically and histopathologically. A greater increase in the level of LDH was observed after 1-hr reperfusion. However, the level of LDH decreased in proportion to the period of reperfusion, while the levels of GOT and GPT were also increased rapidly and reached its peak at 12 hr following reperfusion and were almost restored to the control level by 48 hr. A similar increase was obtained in the lipid peroxides of the liver. In addition, cyt. P-450 content and NADPH cyt. c reductase activity decreased in proportion to the period of reperfusion up to 12 hr and then recovered by 96 hr. On the other hand, heme oxygenase activity was significantly increased by ischemia-reperfusion. The ischemia-reperfused liver resulted in various morphological changes with the period of reperfusion. The destruction of Disse's space, vacuolization of the cytoplasm and nonviable hepatocytes were observed after 12-hr reperfusion. These results indicate the greatest damages of the liver induced by 30-min ischemia following reperfusion is observed after 12-hr or 24-hr reperfusion. The liver injury by ischemia-reperfusion could be a useful experimental model to develop for future studies.
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PMID:[An injury of the liver caused by ischemia-reperfusion in rat liver. Report 2: Relationship between the damage of the liver and during the period of reperfusion]. 146 2

Low-temperature electron paramagnetic resonance (EPR) spectroscopy and spin traps were used to measure paramagnetic species generation in rat hearts and isolated mitochondria. The hearts were freeze-clamped at 77 K during control perfusion by the Langendorff procedure, after 20-30 min of normothermic ischemia or 10-30 s of reperfusion with oxygenated perfusate. All EPR spectra measured at 4.5-50 K exhibited signals of both mitochondrial free radical centers and FeS proteins. The analysis of spectral parameters measured at 243 K showed that free radicals in heart tissue were semiquinones of coenzyme Q10 and flavins. The appearance of a typical "doublet" signal at g = 1.99 in low-temperature spectra indicated that a part of ubisemiquinones formed a complex with a high potential FeS protein of succinate dehydrogenase. Ischemia decreased the free radical species in myocardium approximately 50%; the initiation of reflow of perfusate resulted in quick increase of the EPR signal. Mitochondria isolated from hearts during control perfusion and after 20-30 min of ischemia were able to produce superoxide radicals in both the NADH-coenzyme Q10 reductase and the bc1 segments of the respiratory chain. The rate of oxyradical generation was significantly higher in mitochondria isolated from ischemic heart.
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PMID:Free radical metabolites in myocardium during ischemia and reperfusion. 165 95

Cellular damage of various organs by ischemia following reperfusion is assumed to be at least in part due to lipid peroxidation in biomembranes, and oxygen-derived free radicals play a major role. The level of lipid peroxides in liver tissue increased during 90-min ischemia. When reflow of hepatic blood was allowed, a greater increase in the lipid peroxides was observed. Similar increases were obtained in several serum markers (GOT, GPT and LDH) during the period of ischemia or ischemia-reperfusion. In addition, levels of cytochrome p-450 and NADPH cyt. c reductase activity decreased in proportion to the decrease in microsomal proteins during ischemia or ischemia-reperfusion. On the other hand, superoxide dismutase in blood was significantly increased by ischemia-reperfusion. Rats died within 2 days after liver ischemia of 90 min, while all animals subjected to 30-min ischemia survived. Histopathological examinations indicated that extensive coagulation with erythrocytes occurred and the extent was dependent on the time of ischemia. The liver injury by ischemia-reperfusion could be a useful experimental model for studying liver injury induced by free radicals, for developing hepatoprotective drugs, or for investigating liver transplantation.
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PMID:[An injury of the liver caused by ischemia-reperfusion in rat liver]. 190 28

White mice, 18-20 g, were fed purified diets containing two weight percent safflower oil plus ten weight percent menhaden, corn, or olive oil for 2 wk. Menhaden oil ingestion resulted in significantly higher levels of 22:6(n-3) and 20:5(n-3), particularly 22:6(n-3), and lower levels of 20:4(n-6) and 18:2(n-6) in cardiac sarcoplasmic reticulum (SR) phospholipids than did corn or olive oil ingestion. These changes in fatty acid composition resulted in a significant decrease in the value of the n-6/n-3 fatty acid ratio of cardiac SR phospholipids. The ratio was 2.8 versus 0.2 in choline phospholipids and 1.9 versus 0.2 in ethanolamine phospholipids in SR of mice fed corn or menhaden oil, respectively. This reduction in the n-6/n-3 fatty acid ratio was associated with a lower relative activity of Ca2+-Mg2+ ATPase, and a lower initial rate of calcium transport and maximum calcium uptake in SR vesicles from mice fed menhaden oil rather than olive or corn oils. The specific activity of NADPH cytochrome C reductase (EC 1.6.2.3) of cardiac SR was not affected by dietary lipids. These data indicate that modification of SR by 22:6(n-3) may change the SR bilayer structure resulting in alteration of the calcium transport properties of SR vesicles. In addition, our results suggest that reduction of calcium flux across cardiac SR following fish oil consumption may also reduce the susceptibility of myocytes to rapid changes in calcium concentrations which may occur during ischemia and reperfusion.
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PMID:Ca2+-Mg2+ ATPase of mouse cardiac sarcoplasmic reticulum is affected by membrane n-6 and n-3 polyunsaturated fatty acid content. 252 49

With a variety of forms of ischemic and toxic tissue injury, cellular accumulation of Ca2+ and generation of oxygen free radicals may have adverse effects upon cellular and, in particular, mitochondrial membranes. Damage to mitochondria, resulting in impaired ATP synthesis and diminished activity of cellular energy-dependent processes, could contribute to cell death. In order to model, in vitro, conditions present post-ischemia or during toxin exposure, the interactions between Ca2+ and oxygen free radicals on isolated renal mitochondria were characterized. The oxygen free radicals were generated by hypoxanthine and xanthine oxidase to simulate in vitro one of the sources of oxygen free radicals in the early post-ischemic period in vivo. With site I substrates, pyruvate and malate, Ca2+ pretreatment, followed by exposure to oxygen free radicals, resulted in an inhibition of electron transport chain function and complete uncoupling of oxidative phosphorylation. These effects were partially mitigated by dibucaine, a phospholipase A2 inhibitor. With the site II substrate, succinate, the electron transport chain defect was not manifest and respiration remained partially coupled. The electron transport chain defect produced by Ca2+ and oxygen free radicals was localized to NADH CoQ reductase. Calcium and oxygen free radicals reduced mitochondrial ATPase activity by 55% and adenine nucleotide translocase activity by 65%. By contrast oxygen free radicals alone reduced ATPase activity by 32% and had no deleterious effects on translocase activity. Dibucaine partially prevented the Ca2+-dependent reduction in ATPase activity and totally prevented the Ca2+-dependent translocase damage observed in the presence of oxygen free radicals. These findings indicate that calcium potentiates oxygen free radical injury to mitochondria. The Ca2+-induced potentiation of oxygen free radical injury likely is due in part to activation of phospholipase A2. This detrimental interaction associated with Ca2+ uptake by mitochondria and exposure of the mitochondria to oxygen free radicals may explain the enhanced cellular injury observed during post-ischemic reperfusion.
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PMID:Mechanism of calcium potentiation of oxygen free radical injury to renal mitochondria. A model for post-ischemic and toxic mitochondrial damage. 287 85

Hypercholesterolemia was induced in New Zealand white rabbits by feeding them a 0.5% cholesterol-enriched rabbit chow for 2 wk. Half of the cholesterol-fed rabbits were given lovastatin, a potent inhibitor of hydroxymethylglutaryl-coenzyme A reductase (HMG-CoA reductase), the rate limiting enzyme in cholesterol biosynthesis, and the other half were given its vehicle (i.e., DMSO). At the end of 2 wk, the rabbits underwent experimental myocardial ischemia or a sham ischemia procedure. Ischemic animals fed the cholesterol-enriched diet for 2 wk experienced much greater cardiac damage than ischemic rabbits fed the control diet, despite the absence of any atherosclerosis. Lovastatin was shown to protect the ischemic rabbit myocardium by three different indices of ischemic damage: (a) maintenance of creatine kinase (CK) activity in the ischemic myocardium; (b) reduced loss of free amino-nitrogen containing compounds from the ischemic myocardium; and (c) blunting the rise of plasma CK activity. These effects were not due to differences in myocardial oxygen demand between the groups. Arteries isolated from animals fed the cholesterol-enriched diet developed defects in endothelium-dependent relaxation in both large vessels as well as coronary resistance vessels. Acute hypercholesterolemia increases the severity of myocardial ischemia while at the same time impairing endothelium-dependent relaxation. These deleterious changes can be significantly attenuated by treatment with lovastatin.
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PMID:Cardiovascular effects of acute hypercholesterolemia in rabbits. Reversal with lovastatin treatment. 291 50

The possibility that myocardial ischaemia alters the defence mechanisms against oxygen toxicity has been investigated. Ischaemia was induced in isolated, perfused rabbit hearts by reducing coronary flow from 25 ml/min to 1 ml/min for 90 min. Two different degrees of ischaemic damage have been achieved using either spontaneously beating or electrically stimulated hearts. The effects of post-ischaemic reperfusion were also followed for 30 min. Tissue activity of superoxide dismutase (SOD), glutathione peroxidase and reductase (GPD and GRD) have been determined together with tissue content of reduced and oxidized glutathione (GSH and GSSG) and of protein SH groups. The changes in myocardial ATP and CP content and release of CPK and of GSH and GSSG were also determined. Systolic and diastolic pressures were continuously monitored. In the spontaneously beating hearts ischaemia induced a reduction of tissue GSH and protein SH groups. On reperfusion there was a recovery of mechanical function, a transient release of GSH into the coronary effluent and an increase of tissue GSH. In the paced hearts, ischaemia resulted in 50% reduction of mitochondrial SOD activity together with a reduction of tissue GSH and protein SH groups. Reperfusion induced a massive release of CPK and of GSH and GSSG, a further reduction of tissue GSH concomitant with an increase of GSSG and no recovery of mechanical function. GPD and GRD activity were not affected by ischaemia and reperfusion. These data indicate that severe ischaemia induces a reduction of the protective mechanisms against oxygen toxicity.
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PMID:Oxygen-mediated myocardial damage during ischaemia and reperfusion: role of the cellular defences against oxygen toxicity. 406 39

Ischemic myocardium was produced by occluding the left circumflex coronary artery in anesthetized dogs. Autolyzed myocardium was produced by incubating transmural samples of canine left ventricle at 37 degrees C. Tissue pH was recorded continuously in each model using a microcombination pH electrode impaled into the midmyocardium. The activities of the five mitochondrial inner membrane enzyme complexes of electron transport and coupled oxidative phosphorylation were assayed as a function of time of ischemia or autolysis. While the activities of complex II (succinate-CoQ reductase) and IV (cytochrome c oxidase) were completely stable, that of complex I (NADH-CoQ reductase) decreased markedly, but largely only after 20 min of ischemia or autolysis. At 20 min and beyond, the decrease in the activity of complex I paralleled closely the decrease in whole mitochondrial oxygen uptake with NAD-linked substrates in both models. The activity of complex III (CoQH2-c reductase) decreased at a more gradual rate during ischemia or autolysis, and its rate of decrease paralleled that of succinate-supported oxygen uptake. The activity of complex V (oligomycin-sensitive ATPase) decreased most rapidly (by 40% in only 5 min of autolysis) but nearly leveled off beyond 20 min in the two models. A strikingly similar pattern of differential enzyme lability was observed in isolated control mitochondria incubated at lowered pH values. The results demonstrate 1) differential enzyme lability within the mitochondrial inner membrane, 2) a connection between severity of acidosis and the degree of enzyme activity loss, and 3) the usefulness of simple tissue autolysis as an analogue of in situ myocardial ischemia.
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PMID:Mitochondrial complexes I, II, III, IV, and V in myocardial ischemia and autolysis. 630 12


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