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)

Strategies for balancing energy storage and expenditure during pregnancy were examined in the Djungarian hamster. In expt 1, pregnant hamsters lost nearly 50% of their body lipid stores, even though they showed significant increases in body weight and food intake during the latter half of pregnancy. The increase in body weight was accounted for by the growth of the uteri, fetuses, and placentas. The water and fat-free dry contents of the maternal carcasses did not differ from those of the unmated controls. In expt 2, brown fat cytochrome-c oxidase activity (mitochondrial content) was significantly lower in the late- but not early-pregnant females relative to the nonpregnant controls. Specific GDP-binding levels did not differ significantly among these groups. Thus an overall decrease in total thermogenic activity in brown fat would be expected during late pregnancy. The loss of carcass lipid, despite decreased brown fat thermogenesis and increased food intake, suggests that substantial increases in energy expenditure occur in pregnant females that are not related to heat production in brown fat. The present results are not consistent with traditional models of energy balance during pregnancy. Some of the inconsistencies may be related to differences between hoarding and nonhoarding families of rodents, whereas others may be due to the fact that the traditional model is based on a possibly exceptional species, the laboratory rat.
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PMID:Body composition, food intake, and brown fat thermogenesis in pregnant Djungarian hamsters. 303 61

The ATP/ADP-antiporter inhibitors and ADP decrease the palmitate-induced stimulation of the mitochondrial respiration in the controlled state. The degree of inhibition decreases in the order: carboxyatractylate greater than bongkrekic acid, palmitoyl-CoA, ADP greater than atractylate. GDP is ineffective. The inhibiting concentration of carboxyatractylate coincides with this arresting the state 3 respiration. Carboxyatractylate inhibition decreases when the palmitate concentration increases. Stimulation of controlled respiration by FCCP or gramicidin D at any concentration of these uncouplers is carboxyatractylate-resistant, whereas that by low concentrations of DNP is partially suppressed by carboxyatractylate. These data together with observations that palmitate does not increase H+ conductance in bilayer phospholipid membranes and in cytochrome oxidase-asolectin proteoliposomes indicate that the ATP/ADP-antiporter is somehow involved in the uncoupling by low concentrations of fatty acids (or DNP), whereas that by FCCP and gramicidin D is due to their effect on the phospholipid bilayer. It is suggested that the antiporter facilitates translocation of palmitate anion across the mitochondrial membrane.
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PMID:Carboxyatractylate inhibits the uncoupling effect of free fatty acids. 333 58

The presence of and biochemical background for the so-called 'unmasking' phenomenon in rat brown-fat mitochondria was investigated (i.e. the apparent increase in [3H]GDP binding to the 'uncoupling' protein thermogenin, without a concomitant increase in the amount of the protein). It was found that an unmasking could be observed both 1 h after norepinephrine injection and after 1 h cold stress, provided that the rats were preacclimated to 28 degrees C. The unmasking could be observed both when a filtration method and when a centrifugation method for determination of [3H]GDP-binding capacity were used; however, the absolute values were higher with the filtration method. Based on observations of slower cytochrome-c oxidase sedimentation during centrifugation, the possibility that the matrix volume of brown-fat mitochondria isolated from warm-acclimated animals was smaller than that of cold-stressed animals was investigated with 3H2O. The cold stress increased the matrix volume from being nearly non-existent to about 1 microliter/mg. A preswelling procedure in an ionic medium could similarly increase the matrix volume in mitochondria from warm-acclimated animals but was without significant effect in the already swollen mitochondria from cold-stressed animals or from animals adapted to a lower temperature. In mitochondria from warm-acclimated animals, the ionic preswelling procedure was fully able to increase the apparent amount of GDP binding to that observed in mitochondria from cold-stressed animals, but it was practically without effect on GDP binding in mitochondria from cold-stressed animals or from animals acclimated to a lower temperature. It is concluded that the apparent 'unmasking' phenomenon, observed when the tissue is less activated than in normal control situations, is not (as hitherto anticipated) due to a specific change in thermogenin as such, but is a reflection of a general mitochondrial phenomenon.
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PMID:Apparent unmasking of [3H]GDP binding in rat brown-fat mitochondria is due to mitochondrial swelling. 356 83

The effects of different food deprivation regimens on the thermogenic activity and capacity of brown adipose tissue in the golden hamster have been investigated. Thermogenesis in the tissue was assessed by measurements of tissue cytochrome-c oxidase activity, mitochondrial GDP binding, and the specific mitochondrial concentration of uncoupling protein. The thermogenic activity and capacity of brown adipose tissue were found to be markedly reduced in fasted or underweight hamsters. Measurements of cytochrome-c oxidase activity indicate that the reductions were caused exclusively by a loss in mitochondrial mass, uncoupling protein concentration and GDP binding to mitochondria remaining unchanged. The decrease in brown adipose tissue thermogenesis was associated with a reduction in the capacity for nonshivering thermogenesis in the whole animal. Hamsters recovered from weight losses without increasing their food intake, and the recovery was accompanied by a normalization in mitochondrial mass in brown adipose tissue. Mitochondrial mass was, however, restored only after 10 days of ad libitum refeeding. These results suggest that the reduction in energy expenditure in the fasted hamster could relate to a decrease in brown adipose tissue thermogenesis, in addition to the previously reported decreases in resting metabolic rate and locomotor activity. Reductions in thermogenesis may also represent a further mechanism by which energy stores recover in the golden hamster without postfast hyperphagia.
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PMID:Thermogenic activity and capacity of brown fat in fasted and refed golden hamsters. 357 61

The effects of acute and chronic exposure to different environmental temperatures on the total tissue cytochrome oxidase activity, level of mitochondrial GDP binding, and specific mitochondrial concentration of uncoupling protein have been investigated in rat brown adipose tissue, a radioimmunoassay being used to measure uncoupling protein. Acclimation at different temperatures for 3 wk produced parallel changes in GDP binding, the concentration of uncoupling protein, and the activity of cytochrome oxidase, each parameter rising with decreasing temperature between thermoneutrality (29 degrees C) and 4 degrees C. Acute exposure of warm-acclimated (29 degrees C) rats to the cold (4 degrees C) led to a rapid increase in GDP binding without any alteration in the amount of uncoupling protein. The increase in binding was accompanied by an increase in the rate of acetate-induced swelling of the mitochondria. The concentration of uncoupling protein in warm-acclimated rats was significantly raised only after 48 h exposure to cold. When cold-acclimated rats were exposed acutely to the warm, there was a rapid decrease in GDP binding without any alteration in the amount of uncoupling protein. It is concluded that after alterations in environmental temperature the concentration of uncoupling protein in brown adipose tissue mitochondria changes much more slowly than GDP binding and that binding can therefore be dissociated from the amount of the protein.
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PMID:Effect of warm or cold exposure on GDP binding and uncoupling protein in rat brown fat. 382 41

The thermogenic activity of interscapular brown adipose tissue has been assessed at different stages of pregnancy in mice. In late pregnancy there was a hypertrophy of the tissue which reversed at parturition. Neither the total protein content nor the total cytochrome oxidase activity of the tissue changed significantly throughout pregnancy or into early lactation (2-3 days, post-partum). However, mitochondrial GDP binding, an index of the activity of the proton conductance pathway, was significantly decreased at the end of pregnancy with a further decrease in early lactation. Moderate food restriction had no effect on either cytochrome oxidase activity or mitochondrial GDP binding at the end of pregnancy, as compared with pregnant animals fed ad libitum. Food restriction did, however, prevent the hypertrophy of brown adipose tissue in late pregnancy. It is concluded that brown adipose tissue thermogenesis is not significantly decreased in the pregnant mouse until shortly before parturition, even in animals subject to food restriction. It is also concluded that the normal dietary stimulation of thermogenesis in response to hyperphagia is suppressed in the pregnant animal.
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PMID:Brown adipose tissue thermogenesis during pregnancy in mice. 396 51

Hamsters consuming a "cafeteria diet" had more brown adipose tissue than did chow-fed hamsters. The growth of the brown fat depots in cafeteria-fed hamsters was accompanied by increases in tissue protein and cytochrome oxidase. To assess the thermogenic capacity of brown fat mitochondria, the binding of GDP to isolated mitochondria was measured. Mitochondrial GDP binding was not affected by feeding the cafeteria diet for 4 wk, but more prolonged cafeteria feeding for 8 wk did, however, increase the binding of GDP to isolated mitochondria. The morphology of brown adipose tissue was altered during cafeteria feeding. The brown adipose tissue of cafeteria-fed hamsters had more large unilocular cells than did the brown adipose tissue of chow-fed hamsters. In addition, the average adipocyte diameter was greater in brown adipose tissue of cafeteria-fed hamsters. These data support the presence of a dietary regulation of brown adipose tissue growth in hamsters. The growth of brown adipose tissue in hamsters eating the cafeteria diet appears to result largely from proliferation of adipocytes, as evidenced by the increases in tissue protein and cytochrome oxidase during cafeteria feeding, but some hypertrophy of the adipocytes also occurs. A dietary regulation of brown fat thermogenic capacity is also apparent but this regulation is evident only after more prolonged periods of cafeteria feeding. Hamsters eating a cafeteria diet increase their caloric intake but have the same or greater body weight gain efficiency as do chow-fed animals. The absence of dietary stimulation of thermogenesis may underlie the similar efficiencies of weight gain in chow- and cafeteria-fed hamsters.
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PMID:Brown adipose tissue in cafeteria-fed hamsters. 397 Jan 95

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

The effect of acclimation at different temperatures on the activity of interscapular brown adipose tissue has been investigated in the hamster, a hibernator. Between 31 degrees and 4 degrees C the cytochrome oxidase activity of the tissue increased 4- to 5-fold, mitochondrial GDP binding per mg of mitochondrial protein doubled, and the amount of uncoupling protein rose from 1.7% to 5.4% of total mitochondrial protein. It is concluded that there are clear adaptive changes induced by temperature in brown adipose tissue of the hamster, but the changes are limited in comparison with those in the mouse.
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PMID:Adaptive changes in the concentration of the mitochondrial 'uncoupling' protein in brown adipose tissue of hamsters acclimated at different temperatures. 632 Sep 22

The post-natal development of interscapular brown adipose tissue (BAT) was studied in the guinea pig by monitoring changes in DNA, triglycerides and mitochondrial protein as well as the activity of cytochrome oxidase and atractyloside insensitive GDP-binding. The results demonstrate that neonatal brown fat develops into a tissue with the gross characteristics of white adipose tissue. In this respect the post-natal development of guinea pig BAT is analogous to that of the tissue in man. Furthermore the apparent transformation is not irreversible since cold exposure (+4 degrees C) of adult guinea pigs for six weeks resulted in restoration of cytochrome oxidase, GDP-binding, etc, to levels characteristic of neonatal BAT. However, the interscapular fat pad temperature response to noradrenaline and the presence of 32 000 mol. wt mitochondrial inner membrane protein indicate that the tissue retains thermogenic activity even in warm acclimated adult guinea pigs.
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PMID:Post-natal development of interscapular (brown) adipose tissue in the guinea pig: effect of environmental temperature. 651 Nov 66


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