Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nonsynaptic mitochondria isolated from rat brain hippocampus were compared with those obtained by means of the same preparative procedure from cerebral cortex and striatum. Protein recovery, marker enzyme activities (lactate dehydrogenase, citrate synthase, and acid phosphatase), state 4 respiration, and response to hypoosmotic shock showed no difference among the three cerebral regions, suggesting homogeneous behavior during the subfractionation procedure. Cholinergic markers--choline acetyltransferase, acetylcholinesterase activities, and high-affinity choline uptake--evaluated on synaptosomes showed the classic regional pattern with an enrichment in the striatum (striatum much greater than hippocampus). The coupling state of the mitochondrial fractions was maintained (respiratory control ratios ranging from 3.62 to 5.08 with glutamate + malate as oxidizable substrates), showing a metabolic competence sufficient to perform metabolic studies. Regional differences were found in state 3, uncoupled state of respiration, and cytochrome oxidase activity. Hippocampus showed the lower values (hippocampus less than striatum less than cortex). A possible role of this lower capacity of mitochondrial energy metabolism in determining the sensitivity of hippocampal neurons to ischemia or epileptic seizures is suggested.
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PMID:Oxidative metabolism of nonsynaptic mitochondria isolated from rat brain hippocampus: a comparative regional study. 283 1

Effects of dietary copper deficiency in rats on respiratory enzymes of isolated rat liver mitochondria have been studied. After 2 weeks of Cu-depletion, cytochrome c oxidase (EC 1.9.3.1) activity had declined by 42% and between 4 and 8 weeks exhibited between 20 and 25% of the activity of control mitochondria. Activities of NADH cytochrome c reductase (EC 1.6.99.3) and succinate cytochrome c reductase (EC 1.3.99.1), were unaffected initially but declined by 32 and 46%, respectively, after 8 weeks of Cu-depletion. After 4 weeks there was a significant (34%) decline in succinate supported state 3 respiration with only a modest (18%) decline in state 4 respiration. The ADP:O ratio was unaffected by Cu-depletion after 6 and 8 weeks of dietary Cu-restriction. State 3 respiration was significantly reduced after 6 weeks when glutamate/malate or beta-hydroxybutyrate were used as substrates, whereas state 4 respiration and ADP:O ratios were unaffected. The fall in state 3 respiration was of sufficient magnitude at 8 weeks to cause a significant decline in the respiratory control ratio with all substrates. Comparisons between the relative activities of cytochrome c oxidase and reductase activities in Cu-deficient preparations, the relatively specific effect of the deficiency on state 3 respiration with all substrates tested and the ability to increase significantly oxygen consumption in excess of maximal state 3 respiration by the uncoupler 2,4-dinitrophenol suggest that the defect in Cu-deficient mitochondria cannot be attributed solely to the decreased activity of cytochrome c oxidase.
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PMID:Studies on the effects of copper deficiency on rat liver mitochondria. II. Effects on oxidative phosphorylation. 286 80

Rates of ADP stimulated respiration for various substrates were determined in mitochondria isolated from the livers of female Sprague-Dawley rats following 8 weeks of treatment with daily swimming, ethanol consumption, or both. All rats were fed an American Institute of Nutrition (AIN) type liquid diet with the ethanol treated rats receiving 35% of the calories as ethanol. Chronic exposure to ethanol depressed both state 3 respiration with glutamate as a substrate and cytochrome oxidase activity. Respiratory control ratios and P:O ratios, however, were unaffected by the ethanol exposure. Exercise alone had no effect on hepatic mitochondrial function. There were also no significant alterations in oxidative function of hepatic mitochondria from rats which were endurance-trained by swimming while receiving the ethanol diet. This lack of alteration in mitochondrial function was in spite of the fact that these rats consumed an identical amount of ethanol as those which incurred mitochondrial dysfunction. These results indicate that regular exercise has the potential to attenuate the ethanol induced decline in hepatic mitochondria.
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PMID:Effects of exercise and ethanol on liver mitochondrial function. 288 Nov 81

The neuronal uptake and laminar distribution of cortically injected tritium-labeled gamma-aminobutyrate (GABA), aspartic acid, glutamate and glycine was examined in the prestriate cortex of squirrel monkeys. The intent of this investigation was not to examine the role of these amino acids as neurotransmitters, but to correlate the distribution of tritium-labeled neurons with their levels of cytochrome oxidase activity. A comparison of the number of these labeled neurons was made between the metabolically active "puff" and the less active "nonpuff" regions. In addition, these results were contrasted with the findings in area 17. With each tritiated amino acid tested, labeled neurons that had either high or low levels of cytochrome oxidase activity were present in all laminae. However, the density of labeled neurons varied between lamina for a given amino acid as well as between different amino acids. While many neurons that were cytochrome oxidase-reactive were also tritium-labeled, cytochrome oxidase activity was not a prerequisite for the sequestering of tritium label. In fact, many of the labeled neurons exhibited relatively low levels of cytochrome oxidase activity. Similar to area 17, few aspartate- or glutamate-labeled neurons were present in laminae II-III. The number of labeled neurons for both amino acids increased in laminae IV-VI, with the greatest increase observed in laminae V-VI. Gamma-aminobutyrate-labeled neurons were more prevalent in laminae I and upper II than in the other laminae, whereas in area 17, a greater proportion of the labeled neurons were found in laminae V-VI. With the exception of the uppermost laminae, where GABA-labeled neurons were more abundant, the number of glycine-labeled neurons was significantly greater throughout most laminae than with the other amino acids examined. The density of glycine-labeled neurons in lamina IV, however, was significantly less than the number observed in lamina III even though lamina III was farther away from the injection site which was at the boundary between laminae V-VI. Glycine-labeled neurons were, on average, larger than those labeled with any other amino acid. Similar to area 17, more GABA- and glycine-labeled neurons were observed within the puff regions than in nonpuff regions. No puff/nonpuff differences were observed in the distribution of leucine-injected controls. Labeled neurons for each amino acid included stellate-, fusiform- and pyramidal-shaped cells, each of varying sizes. However, outside the intensely labeled injection sites, no GABA-labeled pyramidal cells were observed.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Neuronal uptake and laminar distribution of tritiated aspartate, glutamate, gamma-aminobutyrate and glycine in the prestriate cortex of squirrel monkeys: correlation with levels of cytochrome oxidase activity and their uptake in area 17. 289 Jan 20

Using immunohistochemical techniques, we demonstrate aspartate aminotransferase (AAT)-like immunoreactivity in cone pedicles and ganglion cells of the cat retina. An identical pattern was seen when we stained for cytochrome oxidase activity, a marker for neurons which have a high metabolic activity. Tetrodotoxin selectively blocked the cytochrome oxidase labeling of ganglion cells. AAT is a key enzyme in the metabolism of aspartate and glutamate and has been proposed as a marker for neurons which use aspartate/glutamate as a neurotransmitter. Due to the close correlation between AAT-like immunoreactivity and cytochrome oxidase activity, we suggest that, at least in the retina, AAT-like immunoreactivity in fact labels cells which have a high metabolic activity.
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PMID:Localization of aspartate aminotransferase and cytochrome oxidase in the cat retina. 298 10

Glucagon has been shown to increase further the enhanced tolerance for hypoxia of mice with elevated blood ketones and to stimulate ketone utilization by rat brain slices, suggesting that glucagon may affect brain metabolism. In addition to stimulating gluconeogenesis, glucagon alters the metabolism of mitochondria isolated from liver and heart. This study was designed to test whether glucagon can act directly and selectively on brain mitochondrial substrate oxidation. Mitochondria were isolated from normal murine brains using differential centrifugation through Ficoll gradients. Glucagon (3.6 microM) stimulated respiration in the presence of glutamate, and glutamate plus beta-hydroxybutyrate, but not in the presence of glutamate plus malate, succinate or beta-hydroxybutyrate alone. With glutamate as the substrate the hormone significantly increased State 3 oxygen consumption rates from control values of 91 mol O2/mol of cytochrome aa3/min to 117 mols O2/mol/aa2/min (p less than 0.0001), and also increased State 4 rates slightly but significantly. Glucagon did not change mitochondrial respiratory control ratios, but increased estimated rates of ATP synthesis from 434 (control) to 597 mols ADP consumed/mol aa3/min (p less than 0.0001). The data indicate that in vitro glucagon has a direct and substrate-specific stimulatory effect on isolated brain mitochondria. These substrate-specific effects were not altered when respiration was studied in the presence of postmitochondrial supernatant or exogenous 3',5'-cyclic AMP, indicating that glucagon, in addition to an in vivo action via activation of membrane-bound adenylate cyclase, can act, at least in vitro, directly and selectively on brain mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Substrate-specific stimulation by glucagon of isolated murine brain mitochondrial oxidative phosphorylation. 300 83

Iron deficiency anemia was induced by dietary means in weanling guinea pigs. A 25% higher ventricular wall mass per 100 g body mass was seen after 6 weeks of feeding. Myocardial performance was determined in isolated perfused hearts using an isovolumic Langendorff preparation. All hearts exhibited a 25% decrease in left ventricular developed pressure (LVDP) and decreased dP/dt when substrate was switched from 10 mM pyruvate to 16.6 mM glucose. The glucose reduction in LVDP resulted from decreased systolic pressure, which completely reversed when hearts again metabolized pyruvate. With glucose as substrate, left ventricular developed pressure-end diastolic volume relationships were indistinguishable. However, with pyruvate, iron-deficient hearts appeared to be less responsive to the increased energy demands required by elevated diastolic volumes. Rates of state 3 respiration were 18% below control with glutamate + malate as substrate, and 38% lower with pyruvate + malate in mitochondria isolated from anemic animals. No differences in respiration were noted with succinate. Cytochrome a + a3 content, cytochrome oxidase activity and total mitochondrial protein content appeared to be unchanged. In contrast, cytochromes b, c + c1, and the flavoproteins were significantly decreased. The data suggest that iron deficiency anemia induces cardiac hypertrophy with a fixed but defective mitochondrial population, potentially placing the heart in an energetic imbalance. These differences in mitochondrial function were expressed by decreased myocardial performance when the heart metabolizes pyruvate, an exclusively aerobic substrate.
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PMID:Substrate-dependent functional defects and altered mitochondrial respiratory capacity in hearts from guinea pigs with iron deficiency anemia. 303 Apr 18

Exposure of rats to elevated temperature of 28 degrees C or 35 degrees C for 3 days six hours daily resulted in a decreased rate of oxidation with succinate or glutamate + malate as substrates, by the mitochondria of liver. The higher decrease was observed in environment temperature of 35 degrees C. There was no change in ADP/O ratio. The activities of NADH: cytochrome c reductase and cytochrome oxidase were stimulated but activities of succinate dehydrogenase and succinate cytochrome reductase were decreased.
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PMID:Influence of increased environmental temperature on oxidation processes in rat liver mitochondria. 303 73

The effect of hypoxia and post-hypoxic recovery were studied in gastrocnemius muscle of young-adult and mature beagle dogs. Furthermore, the possible interference of pharmacological treatment with nicergoline was evaluated in these conditions. Muscular glycolytic fuels, intermediates and end-products (glycogen, glucose, glucose 6-phosphate, pyruvate, lactate), Kreb's cycle intermediates (citrate, alpha-ketoglutarate, succinate, malate) and related free amino acids (glutamate, alanine), ammonium ion, energy store and mediators (ATP, ADP, AMP and creatine phosphate), and the energy charge potential were evaluated. Furthermore, in the crude extract and/or mitochondrial fraction of another portion of the same gastrocnemius muscle the maximum rate (Vmax) of some muscular enzymes related to the anaerobic glycolytic pathway (hexokinase, lactate dehydrogenase), the Kreb's cycle (citrate synthase, malate dehydrogenase), the aminoacid pool related to the Krebs' cycle (glutamate dehydrogenase and aspartate aminotransferase), the electron transfer chain (cytochrome oxidase) and NAD+/NADH exchanges (total NADH cytochrome c reductase) was evaluated. Some glycolytic metabolites and Krebs' cycle intermediates were modified by acute hypoxia, while free amino acids and energy mediators remained practically unchanged. The pharmacological treatment maintained the glucose and succinate muscular concentrations within the normal range, during hypoxia. The behaviour of muscular metabolites during hypoxia and/or post-hypoxic recovery is an age-related event. In fact, only in young-adult animals did the altered values return to normal in post-hypoxic recovery. In the present experimental conditions, only minor changes were observed as far as muscular enzyme activities are concerned. In any case, some enzyme activities tested showed different Vmax in young-adult dogs in comparison with mature ones.
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PMID:Effect of hypoxia, aging and pharmacological treatment on muscular metabolites and enzyme activities. 322 9

The principally mitochondrial enzyme glutamate dehydrogenase (GDH) exhibited low-intensity, uniform immunoreactivity in neurons and intense heterogeneous labeling of glial cells of rat brain. Simultaneous peroxidase labeling for GDH and immunoautoradiography for glial fibrillary acidic protein (GFAP) confirmed the astrocytic localization of the enzyme. Immunoreactivity in astrocytes, but not in neurons, required the presence of Triton X-100 as a solubilizing agent. Most of the intensely labeled glial processes were localized to regions previously reported as containing moderate to high densities of binding sites for the excitatory amino acids, L-glutamate or L-aspartate, and glutamatergic fibers. These included several forebrain regions, such as the superficial layers of the rostral neocortex, dorsal neostriatum, nucleus accumbens, septohippocampal nucleus, intralaminar thalamic nuclei, and external capsules. However, the central gray of the midbrain, the nuclei of the reticular formation, brain stem regions projecting to the cerebellum, and cranial nuclei of the trigeminal and vagal nerves also exhibited intense glial labeling for GDH, even though some of these regions are known to receive only weak glutamatergic projections. A second factor determining the distribution of GDH appeared to be neuronal activity, as assessed by correspondence with reported high densities of cytochrome oxidase. We conclude that GDH enriched in glial populations exists in a subcellular compartment distinct from that of neurons and may serve as one of the enzymes involved in glutamatergic transmission. Deficiencies of glial GDH and the consequent cytotoxic effects of high levels of excitatory amino acids may contribute to a number of neurodegenerative disorders.
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PMID:Regional distribution of astrocytes with intense immunoreactivity for glutamate dehydrogenase in rat brain: implications for neuron-glia interactions in glutamate transmission. 330 25


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