Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rat homologue of a mitochondrial ATP-dependent protease Lon was cloned from cultured astrocytes exposed to hypoxia. Expression of Lon was enhanced in vitro by hypoxia or ER stress, and in vivo by brain ischemia. These observations suggested that changes in nuclear gene expression (Lon) triggered by ER stress had the potential to impact important mitochondrial processes such as assembly and/or degradation of cytochrome c oxidase (COX). In fact, steady-state levels of nuclear-encoded COX IV and V were reduced, and mitochondrial-encoded subunit II was rapidly degraded under ER stress. Treatment of cells with cycloheximide caused a similar imbalance in the accumulation of COX subunits, and enhanced mRNA for Lon and Yme1, the latter another mitochondrial ATP-dependent protease. Furthermore, induction of Lon or GRP75/mtHSP70 by ER stress was inhibited in PERK (-/-) cells. Transfection studies revealed that overexpression of wild-type or proteolytically inactive Lon promoted assembly of COX II into a COX I-containing complex, and partially prevented mitochondrial dysfunction caused by brefeldin A or hypoxia. These observations demonstrated that suppression of protein synthesis due to ER stress has a complex effect on the synthesis of mitochondrial-associated proteins, both COX subunits and ATP-dependent proteases and/or chaperones contributing to assembly of the COX complex.
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PMID:Transmission of cell stress from endoplasmic reticulum to mitochondria: enhanced expression of Lon protease. 1208 77

Homocystinuria is an inherited metabolic disease biochemically characterized by tissue accumulation of homocysteine (Hcy). Mental retardation, ischemia and other neurological features, whose mechanisms are still obscure are common symptoms in homocystinuric patients. In this work, we investigated the effect of Hcy administration in Wistar rats on some parameters of energy metabolism in the hippocampus, a cerebral structure directly involved with cognition. The parameters utilized were 14CO2 production, glucose uptake, lactate release and the activities of succinate dehydrogenase and cytochrome c oxidase (COX). Chronic hyperhomocysteinemia was induced by subcutaneous administration of Hcy twice a day from the 6th to the 28th day of life in doses previously determined in our laboratory. Control rats received saline in the same volumes. Rats were killed 12 h after the last injection. Results showed that Hcy administration significantly diminished 14CO2 production and glucose uptake, as well as succinate dehydrogenase and COX activities. It is suggested that impairment of brain energy metabolism may be related to the neurological symptoms present in homocystinuric patients.
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PMID:Impairment of energy metabolism in hippocampus of rats subjected to chemically-induced hyperhomocysteinemia. 1269 99

Rats fed with ethanol and a nutritious diet intragastrically develop liver pathologic changes associated with cyclic elevation of blood and urinary ethanol levels (BAL and UAL cycle). At the peaks of the UAL cycle, the livers are hypoxic. When the liver portal hepatic blood flow is temporarily clamped for 2 min and then released, the livers at the peak UAL fail to recover completely compared to the control livers and the livers at the UAL cycle troughs. Viagra was fed to the ethanol-fed rats to enhance the effects of nitric oxide. Since nitric oxide is known to increase hepatic blood flow, it was anticipated that Viagra would prevent the liver hypoxia at the UAL cycle peaks and also improve the post-clamp recovery from the post-clamp ischemia challenge. Viagra tended to improve the post-clamp recovery of the liver surface pO2 levels of the ethanol-fed rats probably by slowing O2 consumption as result of NO inhibition of mitochondrial cytochrome c oxidase activity. However, Viagra increased the pathology score when fed with ethanol. For this reason, Viagra is a two-edged sword. On the one hand, it tended to be protective in the post-ischemic injury in the ethanol-fed rats and on the other hand, it enhanced the liver injury caused by ethanol. Viagra did not affect the UAL cycle.
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PMID:The effect of Viagra (sildenafil citrate) on liver injury caused by chronic ethanol intragastric feeding in rats. 1571 34

We have investigated the dynamics of cytochrome c oxidase (COX) activity in the cerebrospinal fluid (CSF) and the erythrocyte haemolysate (EH) in 85 patients suffering from brain infarction (BI), reversible (RIA), or transient (TIA) ischemic attack from the perspective of mitochondrial affection in ischemia. In all patients, the COX activity was decreased in the CSF, especially within the first two days, indicating an acute inactivation or modification of mitochondrial proteins, probably mediated by free radicals. The gradual elevation of COX activity until the seventh day suggested that these changes may be reversible. The increase in the COX activity was established in the EH, with the highest values found in the BI, somewhat lower in the RIA, and the lowest in the TIA group, respectively. This could indicate a systemic compensatory response to an acute ischemia. Thus, COX activity in the CSF and EH in acute ischemia could be an indicator of brain metabolic dysfunction.
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PMID:Dynamics of cytochrome c oxidase activity in acute ischemic stroke. 2759 45

We have investigated the effects of hypoxia and myocardial ischemia/reperfusion on the structure and function of cytochrome c oxidase (CcO). Hypoxia (0.1% O(2) for 10 h) and cAMP-mediated inhibition of CcO activity were accompanied by hyperphosphorylation of subunits I, IVi1, and Vb and markedly increased reactive O(2) species production by the enzyme complex in an in vitro system that uses reduced cytochrome c as an electron donor. Both subunit phosphorylation and enzyme activity were effectively reversed by 50 nm H89 or 50 nm myristoylated peptide inhibitor (MPI), specific inhibitors of protein kinase A, but not by inhibitors of protein kinase C. In rabbit hearts subjected to global and focal ischemia, CcO activity was inhibited in a time-dependent manner and was accompanied by hyperphosphorylation as in hypoxia. Additionally, CcO activity and subunit phosphorylation in the ischemic heart were nearly completely reversed by H89 or MPI added to the perfusion medium. Hyperphosphorylation of subunits I, IVi1, and Vb was accompanied by reduced subunit contents of the immunoprecipitated CcO complex. Most interestingly, both H89 and MPI added to the perfusion medium dramatically reduced the ischemia/reperfusion injury to the myocardial tissue. Our results pointed to an exciting possibility of using CcO activity modulators for controlling myocardial injury associated with ischemia and oxidative stress conditions.
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PMID:Protein kinase A-mediated phosphorylation modulates cytochrome c oxidase function and augments hypoxia and myocardial ischemia-related injury. 1630 65

In spite of opposing changes in rates of adenosine triphosphate turnover, hypertrophy and atrophy of the heart are accompanied by the same changes in gene expression, resembling a fetal genotype. Fetal hearts are characterized by increased ischemia tolerance. We assessed respiratory capacity of mitochondrial subpopulations from unloaded and pressure-overloaded hearts before and after 15 minutes of normothermic ischemia. Unloading was achieved by heterotopic rat heart transplantation and overloading by aortic banding. Respiratory chain gene expression (NADH dehydrogenase, cytochrome c oxidase [COX]) were analyzed by reverse transcriptase-polymerase chain reaction. Subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM) were isolated by differential centrifugation. Citrate synthase was used as mitochondrial marker enzyme. Adenosine diphosphate-stimulated oxygen consumption (state 3) was measured with a Clark-type electrode. Unloading resulted in atrophy, overloading in hypertrophy. State 3 was reduced in atrophied hearts both in SSM and IFM (SSM: 204 +/- 79 vs 804 +/- 147 natoms oxygen min(-1) mL(-1), P < .001; IFM: 468 +/- 158 vs 1141 +/- 296 natoms oxygen min(-1) mL(-1), P < .05), but was unchanged in hypertrophied hearts. NADH dehydrogenase and COX expression was also decreased with atrophy and was unchanged with hypertrophy. Ischemia caused decreased recovery of citrate synthase in isolates of SSM (P < .05) but not of IFM. State 3 in control hearts was reduced in IFM (-41%, P < .01) and SSM (-19%, not significant). This ischemia-induced decrease was less pronounced in SSM (-2%) and IFM (-22%) of atrophied and IFM (-23%) of hypertrophied hearts. Subsarcolemmal mitochondria of hypertrophied hearts displayed the greatest ischemia-induced decrease of state 3 (-32%, P < .05). In conclusion, (1) long-term changes in workload differentially affect maximal respiratory capacity and ischemia tolerance of isolated mitochondria. The changes are not parallel to the changes in energy requirements. (2) Mitochondria of atrophied hearts appear to be more resistant against ischemia than controls.
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PMID:Differential changes in respiratory capacity and ischemia tolerance of isolated mitochondria from atrophied and hypertrophied hearts. 1683 47

Carbon monoxide (CO), which is produced endogenously in the breakdown of heme, has been recognized as an important physiological second messenger similar to NO. Additionally, pharmacological delivery of CO is protective in numerous models of injury, including ischemia/reperfusion, transplantation, hemorrhagic shock, and endotoxemia. However, the mechanism of action of CO is only partially elucidated focused primarily on how it modulates the cellular response to stress. The purpose of these investigations is to test the hypothesis that CO acts via inhibition of cytochrome c oxidase leading to the generation of low levels of reactive oxygen species (ROS) that in turn mediate subsequent adaptive signaling. We show here that CO increases ROS generation in RAW 264.7 cells, which is inhibited by antimycin A and is absent in respiration-deficient rho0 cells. CO inhibits cytochrome c oxidase, while maintaining cellular ATP levels and increasing mitochondrial membrane potential. The addition of antioxidants or inhibition of complex III of the electron transport chain by antimycin A attenuates the inhibitory effects of CO on lipopolysaccharide (LPS)-induced TNF-alpha and blocked CO-induced p38 MAPK phosphorylation, which we previously have shown to be important in the anti-inflammatory effects of CO.
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PMID:Carbon monoxide signals via inhibition of cytochrome c oxidase and generation of mitochondrial reactive oxygen species. 1726 72

We have mapped the sites of ischemia/reperfusion-induced phosphorylation of cytochrome c oxidase (CcO) subunits in rabbit hearts by using a combination of Blue Native gel/Tricine gel electrophoresis and nano-LC-MS/MS approaches. We used precursor ion scanning combined with neutral loss scanning and found that mature CcO subunit I was phosphorylated at tandem Ser115/Ser116 positions, subunit IVi1 at Thr52 and subunit Vb at Ser40. These sites are highly conserved in mammalian species. Molecular modeling suggests that phosphorylation sites of subunit I face the inter membrane space while those of subunits IVi1 and Vb face the matrix side.
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PMID:Site specific phosphorylation of cytochrome c oxidase subunits I, IVi1 and Vb in rabbit hearts subjected to ischemia/reperfusion. 1734 28

Ischemic preconditioning (IPC) strongly protects against ischemia-reperfusion injury; however, its effect on subsequent myocardial oxygenation is unknown. Therefore, we determine in an in vivo mouse model of regional ischemia and reperfusion (I/R) if IPC attenuates postischemic myocardial hyperoxygenation and decreases formation of reactive oxygen/nitrogen species (ROS/RNS), with preservation of mitochondrial function. The following five groups of mice were studied: sham, control (I/R), ischemic preconditioning (IPC + I/R, 3 cycles of 5 min coronary occlusion/5 min reperfusion) and IPC + I/R N(G)-nitro-L-arginine methyl ester treated, and IPC + I/R eNOS knockout mice. I/R and IPC + I/R mice were subjected to 30 min regional ischemia followed by 60 min reperfusion. Myocardial Po(2) and redox state were monitored by electron paramagnetic resonance spectroscopy. In the IPC + I/R, but not the I/R group, regional blood flow was increased after reperfusion. Po(2) upon reperfusion increased significantly above preischemic values in I/R but not in IPC + I/R mice. Tissue redox state was measured from the reduction rate of a spin probe, and this rate was 60% higher in IPC than in non-IPC hearts. Activities of NADH dehydrogenase (NADH-DH) and cytochrome c oxidase (CcO) were reduced in I/R mice after 60 min reperfusion but conserved in IPC + I/R mice compared with sham. There were no differences in NADH-DH and CcO expression in I/R and IPC + I/R groups compared with sham. After 60 min reperfusion, strong nitrotyrosine formation was observed in I/R mice, but only weak staining was observed in IPC + I/R mice. Thus IPC markedly attenuates postischemic myocardial hyperoxygenation with less ROS/RNS generation and preservation of mitochondrial O(2) metabolism because of conserved NADH-DH and CcO activities.
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PMID:Ischemic preconditioning prevents in vivo hyperoxygenation in postischemic myocardium with preservation of mitochondrial oxygen consumption. 1751 95

Controversy surrounds proper classification of neurodegeneration occurring acutely following neonatal hypoxia-ischemia (HI). By ultrastructural classification, in the first 24 h after neonatal hypoxia-ischemia in the 7-day-old (p7) rat, the majority of striatal cells die having both apoptotic and necrotic features. There is formation of a functional apoptosome, and activation of caspases-9 and -3 occurring simultaneously with loss of structurally intact mitochondria to 34.7+/-25% and loss of mitochondrial cytochrome c oxidase activity to 34.7+/-12.7% of control levels by 3 h after hypoxia-ischemia. There is also loss of the mitochondrial motor protein, kinesin. This combination of activation of apoptosis pathways simultaneous with significant mitochondrial dysfunction may cause incomplete packaging of nuclear and cytoplasmic contents and a hybrid of necrotic and apoptotic features. Evidence for an intermediate biochemistry of cell death including expression of the 17 kDa isoform of caspase-3 in dying neurons lacking a classic apoptotic morphology and degradation of the neuronal cytoskeletal protein spectrin by caspase-3 and calcium-activated calpains yielding 120 kDa and 145/150 kDa fragments, respectively, is also found. In summary, neonatal hypoxia-ischemia triggers apoptotic cascades, and simultaneously causes mitochondrial structural and functional failure. The presence of a "continuum" phenotype of cell death that varies on a cell-by-cell basis suggests that the phenotype of cell death is dependent on the energy available to drive the apoptotic pathways to completion.
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PMID:Failure to complete apoptosis following neonatal hypoxia-ischemia manifests as "continuum" phenotype of cell death and occurs with multiple manifestations of mitochondrial dysfunction in rodent forebrain. 1796 29


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