Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of L-carnitine on respiratory chain enzymes in muscle of long distance runners were studied in 14 athletes. These subjects received placebo or L-carnitine (2 g orally b.i.d.) during a 4-week period of training. Athletes receiving L-carnitine showed a significant increase (p < 0.01) in the activities of rotenone-sensitive NADH cytochrome c reductase, succinate cytochrome c reductase and cytochrome oxidase. In contrast, succinate dehydrogenase and citrate synthase were unchanged. No significant changes were observed after placebo administration. The levels of both total and free carnitine from athletes receiving placebo were significantly decreased (p < 0.01) after treatment. By contrast, total and free carnitine levels were markedly increased (p < 0.01) after supplementation with L-carnitine. Our results suggest that L-carnitine induces an increase of the respiratory chain enzyme activities in muscle, probably by mechanisms involving mitochondrial DNA.
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PMID:Respiratory chain enzymes in muscle of endurance athletes: effect of L-carnitine. 132 42

The adaptation of mitochondrial ATP production rate (MAPR) to training and detraining was evaluated in nine healthy men. Muscle samples (approximately 60 mg) were obtained before and after 6 wk of endurance training and after 3 wk of detraining. MAPR was measured in isolated mitochondria by a bioluminometric method. In addition, the activities of mitochondrial and glycolytic enzymes were determined in skeletal muscle. In response to training, MAPR increased by 70%, with a substrate combination of pyruvate + palmitoyl-L-carnitine + alpha-ketoglutarate + malate, by 50% with only pyruvate + malate, and by 92% with palmitoyl-L-carnitine + malate. With detraining MAPR decreased by 12-28% from the posttraining rate (although not significantly for all substrates). No differences were found when MAPR was related to the protein content in the mitochondrial fraction. The largest increase in mitochondrial enzyme activities induced by training was observed for cytochrome-c oxidase (78%), whereas succinate cytochrome c reductase showed only an 18% increase. The activity of citrate synthase increased by 40% and of glutamate dehydrogenase by 45%. Corresponding changes in maximal O2 uptake were a 9.6% increase by training and a 6.0% reversion after detraining. In conclusion, both MAPR and mitochondrial enzyme activities are shown to increase with endurance training and to decrease with detraining.
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PMID:Adaptation of mitochondrial ATP production in human skeletal muscle to endurance training and detraining. 147 78

A quantitative study on the effect of senescence on mitochondrial DNA expression has been carried out by measuring the levels of the 12S rRNA and of the mRNA for the subunit I of cytochrome oxidase in several tissues of adult and senescent rats. The concentration of both RNA species/mitochondrial DNA molecule is significantly reduced in senescent brain and heart, as opposed to the respective adult tissues. No appreciable variation occurs in the liver. A 1-h pretreatment with acetyl-L-carnitine brings back the level of senescent brain and heart transcripts to that of adult tissues. The same treatment of adult rats does not cause significant changes in mitochondrial RNA content. These results suggest that the age-dependent impairment of both heavy-strand mitochondrial DNA transcription units is related to altered environmental conditions which acetyl-L-carnitine, a substance which acts by stimulating, directly or indirectly, the energy metabolism, is able to remove.
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PMID:Reduced transcription of mitochondrial DNA in the senescent rat. Tissue dependence and effect of L-carnitine. 215 75

The effect of acetyl-L-carnitine on the quantity of the messenger RNA for the subunit I of cytochrome oxidase in the liver mitochondria of hypothyroid rat was measured by Northern blot and solution hybridization. Three hours after pre-treatment of hypothyroid rat with acetyl-L-carnitine, the level of the transcript increased strongly. This effect was also obtained when acetyl-L-carnitine was administered to T3 pre-treated hypothyroid rats. These results add further evidence to the suggestion that acetyl-L-carnitine is able to stimulate mitochondrial transcription under altered metabolic conditions.
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PMID:Acetyl-L-carnitine increases cytochrome oxidase subunit I mRNA content in hypothyroid rat liver. 217 13

The effect of aging and subchronic treatment with acetyl-L-carnitine (50 mg/kg per day) was studied on mitochondrial bioenergetics and cholinergic metabolism in non-synaptic mitochondria and synaptosomes isolated from cerebral cortex, hippocampus and striatum of rats aged 4, 11 and 18 months. Respiratory activity and cytochrome oxidase specific activity were unaffected by aging in non-synaptic mitochondria. In synaptosomes, pyruvate dehydrogenase, choline acetyltransferase and acetylcholinesterase specific activity remained unchanged, but the high-affinity choline uptake decreased in cerebral cortex and striatum of 18-month-old rats. Acetyl-L-carnitine treatment increased the high-affinity choline uptake in cerebral cortex of 18-month-old rats. The treatment caused also an increase in cytochrome oxidase activity in all the three cerebral regions and in choline uptake in the hippocampus, parameters that were not directly affected by aging processes.
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PMID:Effect of aging and acetyl-L-carnitine on energetic and cholinergic metabolism in rat brain regions. 254 2

We reported a girl with mitochondrial encephalomyopathy, who had various neuromuscular symptoms including dilated cardiomyopathy, generalized convulsions, myoclonus, muscular weakness and growth retardation. Lactate levels in the serum and CSF were elevated. Muscle biopsy showed scattered ragged-red fibers, and complex I (NADH-CoQ reductase) and complex IV (cytochrome c oxidase) were markedly reduced. Although she was treated with coenzyme Q, DL-carnitine and sodium succinate, she died of progressive congestive heart failure at 9 10/12 years of age.
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PMID:[A case of mitochondrial encephalomyopathy with cardiomyopathy due to decreased complex I and IV activities]. 255 57

Carnitine was administered to a group of patients in shock, and the activities of cytochrome oxidase and succinate cytochrome c reductase in muscle needle biopsies from these patients were compared to those activities present in a non-carnitine treated control group of patients. Carnitine seemingly exerted a significant protective action on cytochrome oxidase activity during the initial phases of shock, but not to such an extent on succinate cytochrome c reductase activities.
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PMID:Effects of L-carnitine administration on mitochondrial electron transport activity present in human muscle during circulatory shock. 299 47

An increase in liver: body-weight and in hepatic triacylglycerol content, together with changes in the fatty acid profiles of hepatic phospholipids, were observed as a result of moderate riboflavin deficiency in sucking rat pups. Oxygen consumption by hepatic mitochondria, with palmitoyl L-carnitine as substrate, was not significantly impaired. Mitochondria from interscapular brown adipose tissue, however, showed a marked impairment of O2 consumption, with palmitoyl L-carnitine as substrate, in the riboflavin-deficient pups. This impairment was also apparent after uncoupling with carbonyl cyanide p-trifluoromethoxyphenylhydrazone, but was not consistently observed after the addition of GDP to suppress uncoupled oxidation. It was much less evident, and did not reach statistical significance, for the mitochondria of brown adipose tissue of the corresponding deficient dams. Binding of 3H-labelled GDP by brown adipose tissue mitochondria was unaffected by riboflavin deficiency in the pups, suggesting that the effect on O2 consumption is more likely to be due to impaired integrity of the mitochondrial respiratory chain, than to impairment of the specific capacity for uncoupling of respiration which is characteristic of brown adipose tissue mitochondria. Total cytochrome c oxidase (EC 1.9.3.1) activity of the brown adipose tissue of riboflavin-deficient pups was not significantly reduced. A small but significant impairment was observed in the stimulation of whole-body O2 consumption by injected noradrenaline in the riboflavin-deficient pups, suggesting that the impairment of brown adipose tissue mitochondrial function may be accompanied by impaired physiological capacity in vivo.
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PMID:Effect of riboflavin deficiency on lipid metabolism of liver and brown adipose tissue of sucking rat pups. 406 55

In the first part of this study, in four dogs the left latissimus dorsi was equipped to perform in vivo contraction measurements and the right latissimus dorsi served as control. After a control period, the dogs received L-carnitine intravenously for 8 wk. We found that carnitine caused the percentage of type I fibers to increase from 30 to 55% in the left latissimus dorsi but no change in the right latissimus dorsi. In the left latissimus dorsi, the contraction speed (percentage ripple) decreased from 75 to 30% and cytochrome-c oxidase activity increased 1.6-fold. No changes occurred in the right latissimus dorsi. To verify these observations, we performed a second study with placebo control for 8 wk, and only the left latissimus dorsi was subjected to weekly electrical stimulation. In the carnitine-treated dogs, the stimulated muscle showed an increase in the percentage of type I fibers from 16 to 35% and the ripple decreased from 92 to 77%. These measures did not change in the placebo-treated dogs. We concluded that weekly short-term stimulation does not lead to a change in fiber type; however, carnitine combined with minimal stimulation of the muscle leads to a significant shift in muscle fiber type composition toward a muscle with an increased content of type I fibers.
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PMID:L-carnitine combined with minimal electrical stimulation promotes type transformation of canine latissimus dorsi. 804 43

The effect of aging and treatment with acetyl-L-carnitine on the activity of cytochrome oxidase and adenine nucleotide translocase in rat heart mitochondria was studied. It was found that the activity of both these mitochondrial protein systems was reduced (by around 30%) in aged animals. Treatment of aged rats with acetyl-L-carnitine almost completely reversed this effect. Changes in the mitochondrial cardiolipin content appear to be responsible for these effects of acetyl-L-carnitine.
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PMID:Effect of aging and acetyl-L-carnitine on the activity of cytochrome oxidase and adenine nucleotide translocase in rat heart mitochondria. 807 May 66


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