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)

The impact of reduced muscle oxidative capacity on peak oxygen consumption and isometric performance was evaluated using an isolated rat hindlimb preparation perfused with a high oxygen delivery. Capacity for electron transport was reduced with chloramphenicol (CAP), an inhibitor of mitochondrial gene-coded protein synthesis. The activity of cytochrome oxidase, a mitochondrial cristae component, was reduced approximately 45% (P less than 0.005) in the mixed-fiber-type plantaris muscle. Several facets of muscle remodeling were also evident with the 10- to 14-day CAP treatment, including decreased citrate synthase activity, increased capillarity, and increased numbers of type IIc fibers. Perfusion of CAP (n = 6) and control (n = 7) rat hindlimbs of similar size with similar total flows (10-11 ml/min) and oxygen contents (20-21 vol%) resulted in similarly high oxygen deliveries to contracting muscles of the hindlimbs (CAP, 9.66 +/- 0.83 mumols.min-1.g-1; control, 8.74 +/- 0.75). Performance of the gastrocnemius-plantaris-soleus group declined in a similar fashion for both groups during increasingly intense near-steady-state tetanic contraction (100 ms at 100 Hz) conditions of 4, 8, 15, 30, 45, and 60 per minute. Oxygen consumption was similar for both groups at rest and increased similarly at each contraction condition. Peak oxygen consumption was not different between CAP (5.34 +/- 0.55 mumols.min-1.g-1) and control (5.74 +/- 0.43) groups and required only 56-68% of the oxygen delivered. This implies that rat skeletal muscle can suffer a significant reduction in its electron transport capacity without impairing peak oxygen consumption and muscle performance.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Impact of reduced cytochrome oxidase activity on peak oxygen consumption of muscle. 216 65

Patients treated for aneurysmal subarachnoid hemorrhage show, in the long-term follow up, an elevated rate of cognitive disturbances that are mainly related to the impact of the initial bleeding: the neurotoxic effects of blood deposition in subarachnoidal spaces may result in a diffuse encephalopathy, but the intrinsic mechanism and the biochemical correlates are not known. In the present study we have evaluated mitochondrial function after experimental induction of subarachnoid hemorrhage. Mitochondrial function was evaluated in four different rat brain areas (frontal cortex, occipital cortex, hippocampus, and brain stem) after experimental isobaric subarachnoid hemorrhage in rats. Subarachnoid hemorrhage was induced by injecting 0.07 mL of arterial autologous blood into the cisterna magna. Intracranial pressure did not significantly increase. The nonsynaptic mitochondrial fraction was isolated from different rat brain areas, and the maximal rate of enzymatic reactions of some key enzymatic activities related to the Krebs cycle [nicotinamide adenine dinucleotide (oxidized form) (NAD+)-isocitrate dehydrogenase, citrate synthase, and succinate dehydrogenase] and of the electron transfer chain (cytochrome oxidase) were evaluated. The nonsynaptic mitochondrial fraction was utilized also to check parameters related to the mitochondrial respiration: state 3, state 4, uncoupled state, respiratory control ratio, and adenosine 5'-diphosphate/oxygen ratio. The biochemical parameters were measured at 1 and 72 hours after the subarachnoidal injection of blood. Subarachnoid hemorrhage did not affect the mitochondrial enzymatic activities both at 1 and 72 hours, while the mitochondrial enzymatic activities parameters were significantly affected: in particular, a significant decrease of respiratory control ratio in all tested brain areas was demonstrated. The increased mitochondrial vulnerability in the delayed phases could be one of the biochemical correlates of post-hemorrhagic encephalopathy.
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PMID:Experimental isobaric subarachnoid hemorrhage: regional mitochondrial function during the acute and late phase. 221 48

In vitro translation of maize scutellar polysome-bound RNA and poly(A)+RNA produces a precursor for the mitochondrial superoxide dismutase (SOD-3) of maize, which can be immunoprecipitated with SOD-3 monospecific antibodies. The precursor SOD-3 (preSOD-3) has both a greater molecular weight and a more positive isoelectric point than the mature (purified) SOD-3. These differences were not observed for the cytosolic isozyme (SOD-4) which was similarly synthesized and isolated. PreSOD-3 specifically associates with maize mitochondria when incubated in vitro, whereas SOD-4 does not. The ionophore valinomycin (at concentrations of over 1 microM) inhibits the uptake of preSOD-3 into mitochondria. The integrity of the mitochondrial preparations was determined by assay of oxygen consumption, citrate synthase, and cytochrome-c oxidase activity.
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PMID:In vitro synthesis, importation and processing of Mn-superoxide dismutase (SOD-3) into maize mitochondria. 244 81

The in vitro metabolism of [1-13C]glucose by Ascaris suum third and fourth-stage larvae was analyzed under different gas phases using 13C nuclear magnetic resonance spectroscopy (13C-NMR). Third-stage larvae (L3) incubated under a gas phase of 85% N2/5% O2/10% CO2 produced trace amounts of [13C]succinate, and molted to fourth-stage larvae (L4) between days 3 and 4 in vitro. However, they appeared to arrest as L3s when incubated under air, or 85% N2/5% O2/10% CO2 in the presence of 2 mM potassium cyanide, or 95% N2/5% CO2. Day 12 L4 (eight days after molting) incubated under 85% N2/5% O2/10% CO2, or 95% N2/5% CO2, or 94% N2/1% O2/5% CO2, produced succinate, acetate, propionate and the branched-chain fatty acids 2-methylvalerate and 2-methylbutyrate by fermentative pathways characteristic of adult body wall muscle. In contrast, when Day 12 L4 were incubated under air, only trace amounts of these acids were detected in the incubation medium. Thus, L4 are capable of synthesizing end-products typical of the adult even in the presence of oxygen, as long as the CO2 tensions are above 5%. As would be predicted, activities of enzymes involved in aerobic metabolism, including citrate synthase, isocitrate dehydrogenase, and cytochrome oxidase, decreased dramatically as L4s underwent the final ecdysis and matured to the adult stage. More importantly, activities of enzymes typical of anaerobic metabolism, including phosphoenolpyruvate carboxykinase and malic enzyme, were substantially elevated in L3s (over their levels in second-stage larvae), and appeared to have reached their adult levels in L3s prior to the third molt, even though L3s still exhibited cyanide sensitivity. Since L3s and L4s have enzymes involved in both aerobic and anaerobic pathways, it is possible that the L3s contain two populations of mitochondria, one which functions aerobically and a second which functions anaerobically.
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PMID:Effect of gas phase on carbohydrate metabolism in Ascaris suum larvae. 250 8

To study the metabolic and functional changes that occur during training with inspiratory flow resistive loads, a chronically instrumented unanesthetized sheep preparation was used. Sheep were exposed to resistances ranging from 50 to 100 cmH2O.l-1.s, for 2-4 h/day, 5-6 days/wk, for a total of 3 wk. Load intensity was adjusted to maintain arterial Po2 (PaO2) above 60 Torr and arterial PCO2 (PaCO2) below 45 Torr. Training produced significant (P less than 0.05) increases in citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, and cytochrome oxidase in the costal and crural diaphragm of the trained sheep (n = 9) compared with control sheep (n = 7). Phosphofructokinase did not increase. In the quadriceps, citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, and phosphofructokinase did not change with training but cytochrome oxidase increased significantly (P less than 0.01). Function of the diaphragm was assessed in a subset of five sheep exposed to the same severe load 1 wk before and 2 days after the final training session. After training, sheep had a lower PaCO2 (10-40%), generated a higher transdiaphragmatic pressure (20-40%), and could sustain this level of transdiaphragmatic pressure for 0.5-2 h longer. The respiratory duty cycle was 10-15% lower, whereas minute ventilation and tidal volume were 20-30% higher in the posttraining test. We conclude that 1) training with inspiratory flow resistive loads improves the performance of the respiratory neuromuscular system and 2) the shift in enzyme profile of the diaphragm is at least in part responsible for this improvement.
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PMID:Metabolic and functional adaptation of the diaphragm to training with resistive loads. 254 Jan 38

In synaptosomes from rat cerebral cortex, the potential catalytic activity of some enzymes related to energy metabolism--namely, phosphofructokinase and citrate synthase--is not affected by aging. In contrast, the maximum velocity (Vmax) of cytochrome oxidase and of pyruvate dehydrogenase decreases in aged rats. A marked increase is found in the Vmax of glucose 6-phosphate dehydrogenase in aged rats and could be related to the availability of NADPH for antiperoxidative processes. Pretreatments of experimental animals with certain drugs were done to investigate the plasticity of enzyme proteins during aging. Papaverine, which acts on macrocirculation, is ineffective, but delta-yohimbine acting on microcirculation and metabolism and almitrine acting on oxygen availability both could interfere with the potential activity of some enzymes. However, their influence differs with the age of the rats.
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PMID:Age-related modification of enzyme activities in synaptosomes isolated from rat cerebral cortex. 254 Mar 42

The effect of Ca2+-homopantothenate (HOPA) treatment (250 mg/kg for 5 d) has been studied by evaluating the specific activity of enzymes related to: glycolytic pathway (hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase), tricarboxylic acid cycle (citrate synthase, malate dehydrogenase), mitochondrial electron transfer chain (succinate dehydrogenase, cytochrome oxidase), NADH redox state (NADH cytochrome c reductase), acetylcholine metabolism (acetylcholinesterase), and glutamate metabolism (glutamate dehydrogenase). The enzymatic activity assays were performed on homogenate in toto, nonsynaptic mitochondria and synaptosomes isolated from: cerebral cortex, hippocampus, striatum, hypothalamus, medulla oblongata, and cerebellum of normoxic rats and rats submitted to intermittent normobaric hypoxia (90:10, N2:O2). In normoxic rats, HOPA was unable to induce any modification. Hypoxia per se induced a decrease in the activity of synaptosomal cytochrome oxidase in cerebral cortex, hippocampus, and cerebellum.
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PMID:Effect of Ca2+-homopantothenate and mild hypoxia on some enzyme activities evaluated in subcellular fractions from different rat brain regions. 254 16

When pharmacological or basic neurochemical systematic characterization of mitochondrial enzymatic systems correlated to energy transduction processes is attempted, studies must be based on subcellular fractions with a high degree of purity from specific brain areas and from individual animals. Distinct populations of mitochondria heterogenous with respect to biochemical enzyme characteristics from rat brain hippocampus are described. Two mitochondrial populations were derived from synaptosomes by lysis and a third consists of free non-synaptic mitochondria. The maximum rate of some cerebral enzyme activities which are part of energy transduction (citrate synthase, malate dehydrogenase; total NADH-cytochrome c reductase, cytochrome oxidase) and amino acid metabolism (glutamate dehydrogenase) were tested on these mitochondrial populations of 8- and 16-week-old rats. A comprehensive analysis of the data suggests that extensive but highly diversified catalytic expressions of the enzymes studied occur in the hippocampus. This is true even when a short period of the rat life span is studied. Hence the varying pattern of evolution of the differing cerebral mitochondria, probably a consequence of different metabolic functions, should be taken into account in any pharmacological study on these systems.
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PMID:Enzyme activities in perikaryal and synaptic mitochondrial fractions from rat hippocampus during development. 255 73

The purposes of the present study were to characterize the histochemical and enzymatic profiles of various hindlimb skeletal muscles, as well as to determine maximal O2 consumption (VO2max) and respiratory exchange ratios (R) during steady-state exercise in the obese Zucker rat. The changes that occurred in these parameters in response to a 6-wk training program were then assessed. Obese rats were randomly assigned to a sedentary or training group. Lean littermates served as a second control. Training consisted of treadmill running at 18 m/min up an 8% grade, 1.5 h/day, 5 day/wk for 6 wk. During week 6, VO2max and R during a steady-state run (74% max) were determined. After 2 days of inactivity, hindlimb muscles were excised, stained for fiber type and capillaries, and assayed for hexokinase, citrate synthase, cytochrome oxidase, and beta-hydroxyacetyl-CoA dehydrogenase. The obese sedentary rats demonstrated greater oxidative enzyme activities per gram of muscle tissue than their lean littermates, greater R values during submaximal exercise of the same relative intensity, and greater absolute VO2max values. Training resulted in a 20-56% increase in oxidative enzymes, a 10% increase in VO2max, and an increase in capillary density in the soleus and plantaris. There was no alteration in R values during exercise at 74% VO2max or in fiber type composition in response to exercise training. Results suggest that the muscle of the obese Zucker rat manifests a greater oxidative capacity than the muscle of its lean littermates. The apparent inability of the obese rat to increase its use of fat during submaximal exercise of the same relative intensity in response to training remains to be elucidated.
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PMID:Muscle morphological and biochemical adaptations to training in obese Zucker rats. 255 20

23-month-old male rats were trained by running for 20 weeks. The oxidation rates of succinate, glutamate+malate, palmitoylcarnitine, and pyruvate and the activities of lactate dehydrogenase, citrate synthase, isocitrate dehydrogenase and cytochrome oxidase were measured in the subendocardium and subepicardium and in the right ventricle. Regional differences of substrate oxidation rates in the myocardium of old sedentary or trained rats were less than in young rats, suggesting that regional differences in the cardiac work load disappear during ageing. Training did not improve oxidation rates, in contradiction to some previous results.
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PMID:Effects of training on regional substrate oxidation in the hearts of ageing rats. 256 Sep 87


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