首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
Summary Goldfish acclimated to normal oxygen levels and to 20°C were made anoxic and injected i.p. with U-14C-glucose, 6-14C-glucose, U-14C-lactate, 3-14C-lactate, 1-14C-acetate or 3,4-14C-glutamate. Radioactivity released into the water (total14C and14CO2) was monitored over a period of about 12 h. With the exception of 3,4-14C-glutamate from which only 4% was released, the release of14C from the other compounds was found to be over 30%. The fraction of the radioactivity released as CO2 varied with the compound injected but was high during the first 4 h after injection. It is argued that the acid-stable14C component is ethanol, which arises by the combined action of a modified pyruvate dehydrogenase and of alcohol dehydrogenase in muscle (Shoubridge and Hochachka 1980; Mourik et al. 1982).14CO2 release from 3-14C-lactate, 6-14C-glucose, 3,4-14C-glutamate and 1-14C-acetate cannot be explained by ethanol fermentation. Neither was there a stoichiometric relation between14CO2 and14C-ethanol release after U-14C-glucose and U-14C-lactate injection. It is concluded that at least 20% of the CO2 released is produced by Krebs cycle activity.  相似文献   

2.
The present study assesses the effects of starvation and refeeding on 1-[14C]-methyl aminoisobutyric acid (14C-MeAIB) uptake, 14C-total lipids, 14CO2 production from 14C-glycine, 14C-protein synthesis from 14C-leucine and Na+–K+-ATPase activity in jaw muscle of Neohelice granulata previously maintained on a carbohydrate-rich (HC) or high-protein (HP) diet. In N. granulata the metabolic adjustments during starvation and refeeding use different pathways according to the composition of the diet previously offered to the crabs. During starvation, 14CO2 production from 14C-glycine, and 14C-protein synthesis from 14C-leucine were reduced in HC-fed crabs. In crabs maintained on the HP or HC diet, 14C-total lipid synthesis increased after 15 days of starvation. In crabs fed HP diet, 14C-MeAIB uptake and Na+–K+-ATPase activity decreased in refeeding state. In crabs refeeding HC diet, 14C-MeAIB uptake and 14CO2 production decreased during the refeeding. In contrast, the 14C-protein synthesis increased after 120 h of refeeding. In both dietary groups, 14C-total lipid synthesis increased during refeeding. Changes in the carbon amino acid flux between different metabolic pathways in muscle are among the strategies used by this crab to face starvation and refeeding. Protein or carbohydrate levels in the diet administered to this crab modulate the carbon flux between the different metabolic pathways.  相似文献   

3.
We investigated the transport of 14C-methylaminoisobutyric acid (14C-MeAIB) and 14C-alanine oxidation in hepatopancreas and jaw muscle of Chasmagnathus granulata submitted to 24, 72, and 144 h of hypo- or hyperosmotic stress. While 14C-MeAIB uptake increased in jaw muscle and hepatopancreas from crabs submitted to hyperosmotic stress, it did not change in tissues from animals submitted to hypo-osmotic stress. Incubation of jaw muscle and hepatopancreas from control groups with 1 mM ouabain did not decrease 14C-MeAIB uptake. However, ouabain prevented 14C-MeAIB uptake in hepatopancreas at 24 h of hyperosmotic stress. In contrast, in jaw muscle from crabs submitted to the same conditions, 14C-MeAIB uptake was not prevented by ouabain in the incubation medium. Jaw muscle from the control group produced four times more 14CO2 from 14C-alanine than the hepatopancreas. During hypo-osmotic stress, amino acid oxidation does not seem to be one of the pathways implicated in the decrease of the amino acid pools in hepatopancreas and jaw muscle. In contrast, during hyperosmotic stress the reduction in 14C-alanine oxidation appears to be one of the mechanisms involved in the increase of the amino acid pool in the hepatopancreas.  相似文献   

4.
Viil  J.  Ivanova  H.  Pärnik  T.  Pärsim  E. 《Photosynthetica》2004,42(2):283-290
High CO2 concentrations (HC) in air induce partial deactivation of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO, EC 4.1.1.39). Under saturating irradiance, increase in [CO2] to 1 200 cm3 m–3 reduces the concentration of operating carboxylation centres by 20–30 %. At a further increase in [CO2], the activity remained on the same level. Under limiting irradiance, the lowest activity was reached at 600 cm3(CO2) m–3. The presence of oxygen diminished deactivation, but O2 failed to stimulate reactivation under high CO2. Conditions that favour oxygenation of ribulose-1,5-bisphosphate (RuBP) facilitated reactivation. Even HC did not act as an inhibitor. HC induces deactivation of RuBPCO by increasing the concentration of free reaction centres devoid of the substrate, which are more vulnerable to inhibition than the centres filled with substrates or products.  相似文献   

5.
Aerobic and anaerobic metabolism in Entamoeba histolytica   总被引:4,自引:0,他引:4  
Respiration by Entamoeba histolylica is confirmed. A doubling of the rate of oxygen uptake was observed upon the addition of d-glucose to cells in which the glycogen reserve had been partially depleted. In cells metabolizing endogenous substrates the rate of oxygen uptake was not influenced by sodium cyanide or sodium succinate. It was slightly depressed when d-mannose was the added sugar. The end products, CO2, ethanol, and acetate accounted for essentially all of the glucose carbon utilized in both aerobic and anaerobic experiments. The radioactivity from uniformly labelled 14C-glucose was found in these products. Three times as much ethanol as acetate was produced in the anaerobic experiments and in the aerobic experiments this ratio was approximately reversed.  相似文献   

6.
The degradation rate of [synthetic-14C]-lignin to 14CO2 by Phanerochaete chrysosporium in cultures buffered with 0.01 M 2,2-dimethylsuccinate (DMS) was twice that in 0.01 M o-phthalate-buffered cultures. This difference could be totally accounted for by o-phthalate inhibition of the activity of the ligninolytic system. 14CO2 production from ring-, sidechain-, and methoxyl-labeled lignins was inhibited, the degree of inhibition being dependent on o-phthalate concentration. Oxidations of 14C-glucose, 14C-acetovanillone, and 14C-apocynol were not inhibited; thus o-phthalate is not a general inhibitor, and might inhibit activities involved in attack of the lignin polymer. DMS is a suitable buffer for the ligninolytic system. Degradation rates of ring-labeled lignin to 14CO2 of 10–15% in 24 h were obtained consistently over the pH range 3.6–4.5, with an optimum near pH 4.0.Non-Standard Abbreviations DMS dimethylsuccinate  相似文献   

7.
Partitioning of 14C was assessed in sweet chestnut seedlings (Castanea sativa Mill.) grown in ambient and elevated atmospheric [CO2] environments during two vegetative cycles. The seedlings were exposed to 14CO2 atmosphere in both high and low [CO2] environments for a 6-day pulse period under controlled laboratory conditions. Six days after exposure to 14CO2, the plants were harvested, their dry mass and the radioactivity were evaluated. 14C concentration in plant tissues, root-soil system respiratory outputs and soil residues (rhizodeposition) were measured. Root production and rhizodeposition were increased in plants growing in elevated atmospheric [CO2]. When measuring total respiration, i.e. CO2 released from the root/soil system, it is difficult to separate CO2 originating from roots and that coming from the rhizospheric microflora. For this reason a model accounting for kinetics of exudate mineralization was used to estimate respiration of rhizospheric microflora and roots separately. Root activity (respiration and exudation) was increased at the higher atmospheric CO2 concentration. The proportion attributed to root respiration accounted for 70 to 90% of the total respiration. Microbial respiration was related to the amount of organic carbon available in the rhizosphere and showed a seasonal variation dependent upon the balance of root exudation and respiration. The increased carbon assimilated by plants grown under elevated atmospheric [CO2] stayed equally distributed between these increased root activities. ei]H Lambers  相似文献   

8.
A comparison of branchial enzyme profiles indicates that the gills of Periophthalmodon schlosseri would have a greater capacity for energy metabolism through glycolysis than those of Boleophthalmus boddaerti. Indeed, after exposure to hypoxia, or anoxia, there were significant increases in the lactate content in the gills of P. schlosseri. In addition, exposure to hypoxia or anoxia significantly lowered the glycogen level in the gills of this mudskipper. It can be deduced from these results that the glycolytic flux was increased to compensate for the decrease in ATP production through anaerobic glycolysis. Different from P. schlosseri, although there was an increase in lactate production in the gills of B. boddaerti exposed to hypoxia, there was no significant change in the branchial glycogen content, indicating that a reversed Pasteur effect might have occurred under such conditions. In contrast, anoxia induced an accumulation of lactate and a decrease in glycogen in the gills of B. boddaerti. Although lactate production in the gills of these mudskippers during hypoxia was inhibited by iodoacetate, the decreases in branchial glycogen contents could not account for the amounts of lactate formed. The branchial fructose-2,6-bisphosphate contents of these mudskippers exposed to hypoxia or anoxia decreased significantly, leaving phosphofructokinase and glycolytic rate responsive to cellular energy requirements under such conditions. The differences in response in the gills of B. boddaerti and P. schlosseri to hypoxia were possibly related to the distribution of phosphofructokinase between the free and bound states.Abbreviations ADP adenosine diphosphate - ALD aldolase - ALT alanine transaminase - AST aspartate transaminase - ATP adenosine triphosphate - CS citrate synthase - EDTA ethylenediaminetetra-acetic acid - EGTA ethylene glycol tetra-acetic acid - F6P fructose-6-phosphate - F-1,6-P2 fructose-1,6-bisphosphate - F-2,6-P2 fructose-2,6-bisphosphate - FBPase fructose-1,6-bisphosphatese - GAPDH glyceraldehyde-3-phosphate dehydrogenase - GDH glutamate dehydrogenase - -GDH -glycerophosphate dehydrogenase - GPase glycogen phosphorylase - HK hexokinase - HOAD 3-hydroxyacyl-CoA dehydrogenase - IDH isocitrate dehydrogenase - IOA iodoacetic acid - LDH lactate dehydrogenase - LO lactate oxidizing activity - MDH malate dehydrogenase - 3-PG 3-phosphoglyceric acid - PEP phosphoenolpyruvate - PEPCK phosphoenolpyruvate carboxykinase - PGI phosphoglucose isomerase - PGK phosphoglycerate kinase - PFK 6-phosphofructo-1-kinase - PIPES piperazine-N, N-bis-(2-ethanesulphonic acid) - PK pyruvate kinase - PMSF phenylmethylsulphonyl fluoride - PR pyrurate reducing activity - SE standard error - SW seawater - TPI triosephosphate isomerase  相似文献   

9.
The influence of phosphate deficiency on the sugar accumulation and sugar partitioning in the root cells of bean (Phaseolus vulgaris L.) was studied. Bean plants were cultured 17 - 19 d on a phosphate-sufficient and phosphate-deficient nutrient medium. Phosphate deficit in the growth medium resulted in increased sugar concentration for about 30 % in the apoplastic and cytoplasmic compartments as well as in the vacuoles of root cells. However, the distribution of sugars between apoplast and cytoplasm compartment and vacuole was not affected by decreased phosphate concentration. About 20 % of sugars were found in the apoplast and cytoplasm, about 80 % in the vacuole. Low phosphate concentration enhanced influx of exogenous 14C-sucrose into meristematic and elongation zones of root. The 14C-labelled sugar content in the root tips increased for about 60 % as compared to control plants. Phosphate deficiency increased also 14C-glucose uptake and content in the root tips. However, the amount of 14CO2 liberated during respiration of P-deficient roots (after feeding with uniformly labelled 14C-glucose) was lower than 14CO2 respired by control plants, thus a large part of accumulated sugars seems to be metabolically inactive. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

10.
Summary The mechanisms of glycolytic rate control during hibernation in the ground squirrel Spermophilus lateralis were investigated in four tissues: heart, liver, kidney, and leg muscle. Overall glycogen phosphorylase activity decreased significantly in liver and kidney to give 50% or 75% of the activity found in the corresponding euthermic organs, respectively. The concentration of fructose-2,6-bisphosphate (F-2,6-P2) decreased significantly in heart and leg muscle during hibernation to 50% and 80% of euthermic tissue concentrations, respectively, but remained constant in liver and kidney. The overall activity of pyruvate dehydrogenase (PDH) in heart and kidney from hibernators was only 4% of the corresponding euthermic values. Measurements of phosphofructokinase (PFK) and pyruvate kinase (PK) kinetic parameters in euthermic and hibernating animals showed that heart and skeletal muscle had typical rabbit skeletal M-type PFK and M1-type PK. Liver and kidney PFK were similar to the L-type enzyme from rabbit liver, whereas liver and kidney PK were similar to the M2 isozyme found primarily in rabbit kidney. The kinetic parameters of PFK and PK from euthermic vs hibernating animals were not statistically different. These data indicate that tissue-specific phosphorylation of glycogen phosphorylase and PDH, as well as changes in the concentration of F-2,6-P2 may be part of a general mechanism to coordinate glycolytic rate reduction in hibernating S. lateralis.Abbreviations ADP adenosine diphosphate - AMP adenosine monophosphate - ATP adenonine triphoshate - EDTA ethylenediaminetetra-acetic acid - EGTA ethylene glycol tetra-acetic acid - F-6-P fructose 6-phosphate - F-1,6-P2 fructose 1,6-bisphosphate - F-2,6-P2 fructose-2,6-bisphosphate - K a activation coefficient - I50 concentration of inhibitor which reduces control activity by 50% - PDH pyruvate dehydrogenase - PEP phosphoenolpyruvate - PFK 6-phosphofructo-1-kinase - PK pyruvate kinase  相似文献   

11.
Tobacco pith-phloem explants and callus were incubated in 14C-glucose, 14C-acetate or 14C-bicarbonate on different days in culture in the dark. 14CO2 production and 14C incorporation into ethanol-insoluble components were generally greater in the subcultured callus than in the pith-phloem explants during days 0 to 5 in culture. Greatest radioactivity from all substrates was in the ethanol-soluble portion, which was further fractionated into lipids, amino acids, sugars and organic acids. Although incorporation into the different fractions varied with the substrate, the patterns of labelling were relatively similar in the two tissues. The greater wound metabolism in the subcultured callus in comparison to the pith-phloem explant during the induction phase of callus formation was correlated with the earlier visible initiation of cell proliferation in the subcultured tissue.  相似文献   

12.
Ghost crabs Ocypode ceratophthalmus were exercised in air and water to measure CO2 and O2 exchange rates using the method of instantaneous measurements of oxygen consumption rate (MO2) where applicable. Average heart rate increased from 100 to nearly 400 pulses per minute after five minutes of exercise on a treadmill at a run rate of 0.133 m s?1. It took less than a minute for oxygen taken up through the lung epithelium from the air inside the branchial cavity to reach the maximal oxygen consumption rate of 26.1 mmol O2 kg?1 h?1. Resting MO2 was 4.06 mmol O2 kg?1 h?1 in air, but decreased to 3.37 mmol O2 kg?1 h?1 in seawater. Radioactive CO2 from injected l-lactate is released linearly by the lung. The percent accumulated 14-CO2 in exhaled air, plotted against time, intersects zero time on the x -axis, indicating rapid gas exchange at the lung surface. The P 50 values for native haemocyanin of 4.89 mm Hg before exercise, and 8.99 mm Hg after exercise, are typical of a high-affinity haemocyanin usually associated with terrestrial crabs. The current notion that Ocypode ceratophthalmus drown when submerged in seawater was not substantiated by our experiments. MO2 in seawater increased from 3.37 mmol O2 kg?1 h?1 for resting crabs to 5.72 mmol O2 kg?1 h?1 during exercise. When submerged by wave-seawater in the natural environment and during exercise in respirometer-seawater O. ceratophthalmus do not swim but, having a specific density of 1.044, float nearly weightless with a minimum of body movements.  相似文献   

13.
The aim of this work was to examine the response of wheat plants to a doubling of the atmospheric CO2 concentration on: (1) carbon and nitrogen partitioning in the plant; (2) carbon release by the roots; and (3) the subsequent N uptake by the plants. The experiment was performed in controlled laboratory conditions by exposing fast-growing spring wheat plants, during 28 days, to a 14CO2 concentration of 350 or 700 L L–1 at two levels of soil nitrogen fertilization. Doubling CO2 availability increased total plant production by 34% for both N treatment. In the N-fertilized soil, the CO2 enrichment resulted in an increase in dry mass production of 41% in the shoots and 23% in the roots; without N fertilization this figure was 33% and 37%, respectively. In the N-fertilized soil, the CO2 increase enhanced the total N uptake by 14% and lowered the N concentration in the shoots by 23%. The N concentration in the roots was unchanged. In the N-fertilized soil, doubling CO2 availability increased N uptake by 32% but did not change the N concentrations, in either shoots or roots. The CO2 enrichment increased total root-derived carbon by 12% with N fertilization, and by 24% without N fertilization. Between 85 and 90% of the total root derived-14C came from respiration, leaving only 10 to 15% in the soil as organic 14C. However, when total root-derived 14C was expressed as a function of root dry weight, these differences were only slightly significant. Thus, it appears that the enhanced carbon release from the living roots in response to increased atmospheric CO2, is not due to a modification of the activity of the roots, but is a result of the increased size of the root system. The increase of root dry mass also resulted in a stimulation of the soil N mineralization related to the doubling atmospheric CO2 concentration. The discussion is focused on the interactions between the carbon and nitrogen allocation, especially to the root system, and the implications for the acquisition of nutrients by plants in response to CO2 increase.Abbreviations N soil fertilization without nitrogen - N soil fertilization with nitrogen  相似文献   

14.
Silvola  Jouko  Ahlholm  Urpo 《Plant and Soil》1995,(1):547-553
Birch seedlings (Betula pendula) were grown for four months in a greenhouse at three nutrient levels (fertilization of 0, 100 and 500 kg ha-1 monthy) and at four CO2 concentrations (350, 700, 1050 and 1400 ppm). The effect of CO2 concentration on the biomass production depended on the nutrient status. When mineralization of the soil material was the only source of nutrients (0 kg ha-1), CO2 enhancement reduced the biomass production slightly, whereas the highest production increase occurred at a fertilization of 100 kg ha-1, being over 100% between 350 and 700 ppm CO2. At 500 kg ha-1 the production increase was smaller, and the production decreased beyond a CO2 concentration of 700 ppm. The CO2 concentration had a slight effect on the biomass distribution, the leaves accounting for the highest proportion at the lowest CO2 concentration (350 ppm). An increase in nutrient status led to a longer growth period and increased the nutrient concentrations in the plants, but the CO2 concentration had no effect on the growth rhythm and higher CO2 reduced the nutrient concentrations.  相似文献   

15.
Photosynthetic14CO2 assimilation, ribulose 1, 5-bisphosphate carboxylase (RuBPC), phosphoenol pyruvate carboxylase (PEPC) and dry matter (DM) production were examined in wheat under varying levels and forms of nitrogen.14CO2 assimilation increased gradually after germination reaching a peak value at anthesis, followed by a sharp decline. A similar pattern was observed for both the carboxylases, RuBPC and PEPC activities. Increase in nitrogen levels, in general, brought about a significant increase over the control (zero-nitrogen) in14CO2 assimilation, RuBPC, PEPC activities and DM production. There were no significant differences in RuBPC activity and14CO2 assimilation with respect to the forms of nitrogen. Significantly higher PEPC activity and DM was observed in plants supplied with nitrate-nitrogen (NO3-N), as compared to those supplied with ammonium-nitrogen (NH4-N). The significance of PEPC activity in C3 photosynthesis is discussed in relation to DM distribution.  相似文献   

16.
14CO2 assimilation, 14C incorporation into glycolate and glycolate accumulation in -HPMS treated bean leaves at various O2 and CO2 concentrations were studied. In 1% CO2 oxygen concentration had no significant effect on glycolate accumulation and 14C incorporation into glycolate. In the CO2 concentration range of 0.03% to 0.01%, increased oxygen concentration decreased not only 14CO2 assimilation but also glycolate accumulation and 14C incorporation into glycolate. In 1% and 0.1% CO2, no matter what O2 concentration was supplied, and in 0.03% CO2 with 2% and 21% O2, all of the glycolate accumulated was formed from newly assimilated carbon. In 0.01% CO2 and 2%, 21% and 100% O2, and in 0.03% CO2 with 100% O2, a substantial portion of the glycolic acid that accumulated in leaves originated from endogenous unlabelled substrates. These findings are discussed in terms of possible changes in the ratio of RuBP carboxylation to RuBP oxygenation and of changes of RuBP pool size, induced by changing O2 and CO2 concentrations.This work was supported by the Polish Academy of Sciences, Contract No. 10.2.10.  相似文献   

17.
Metabolic fate of lactate after strenuous exercise which lasted 2-3 min was investigated in rats and mice. 14C-labeled lactate or glucose was injected into the aorta of rats through an catheter. 14C-glucose was injected intraperitoneally into the mice after supramaximal exercise. The mice ran twice with a 4 hr interval to investigate muscle 14C-lactate metabolism which was produced from muscle 14C-glycogen. A great deal of blood and muscle 14C-lactate was expired as 14CO2 after the exercise. The results indicate that oxidative removal is the major fate of lactate metabolism after strenuous exercise and that blood glucose is the major substrate for muscle glycogen resynthesis. Light intensity exercise after strenuous exercise (active recovery) enhances oxidative removal of blood and muscle lactate. Gluconeogenesis from lactate to glycogen within the skeletal muscle is not a major pathway of muscle lactate metabolism, while high intensity training can activate this pathway.  相似文献   

18.
Tolbutamide partially inhibited the growth but increased the glycogen content of Tetrahymena pyriformis in logarithmically growing cultures. Tolbutamide slightly increased 14CO2 production from [1-14C] and [6-14HC] glucose and [2-14C] pyruvate, but had little effect on the oxidation of [1-14C] acetate when any of these substrates were added to the proteose-peptone medium in which the cells had been grown. Measurement of 14CO2 production from [1-14C] and [2-I4C]-glyoxylate showed that this substrate was primarily oxidized via the glyoxylate cycle, with little if any oxidation occurring via the peroxisomal glyoxylate oxidase. Addition of tolbutamide inhibited the glyoxylate cycle as indicated by a marked reduction in label appearing in CO2 and in glycogen from labeled acetate. In control cells, addition of acetate strongly inhibited the oxidation of [2-14C]-pyruvate whereas addition of pyruvate had little effect on the oxidation of [1-14C]-acetate. Acetate was more effective than pyruvate in preventing the growth inhibitory and glycogen-increasing effects of tolbutamide. The data suggest that one effect of tolbutamide may be to interfere with the transfer of isocitrate and acetyl CoA across mitochondrial membranes.  相似文献   

19.
Harrison PW  Kruger NJ 《Phytochemistry》2008,69(17):2920-2927
The aim of this study was to examine whether flux through the pathways of carbohydrate oxidation is accurately reflected in the pattern of 14CO2 release from positionally labelled [14C]substrates in conventional radiolabel feeding studies. Heterotrophic cell suspension cultures of Arabidopsis thaliana were used for this work. The presence of an alkaline trap to capture metabolically generated 14CO2 had no significant effect on the ratio of 14CO2 release from specifically labelled [14C]substrates, or on the metabolism of [U-14C]glucose by the cells. Although the amount of 14CO2 captured in a conventional time-course study was only about half of that released from a sample acidified at an equivalent time point, the ratios of 14CO2 released from different positionally labelled [14C]glucose and [1-14C]gluconate were the same in untreated and acidified samples. Less than 5% of radioactivity supplied to the growth medium as [14C]bicarbonate was incorporated into acid-stable compounds, and there was no evidence for appreciable reassimilation of 14CO2 generated intracellularly during oxidation of [1-14C]gluconate by the cells. It is concluded that the ratio of label captured from specifically labelled [14C]glucose is a valid and convenient measure of the relative rates of oxidation of the different positional carbon atoms within the supplied respiratory substrate. However, it is argued that failure to compensate for the incomplete absorption of 14CO2 by an alkaline trap may distort estimates of respiration that rely on an absolute measure of the amount of 14CO2 generated by metabolism.  相似文献   

20.
This paper reports the determination of the ability of rat heart cells in culture to release [14C]palmitate from its triglyceride and to oxidize this fatty acid and free [14C]palmitate to 14CO2 when the cells are actively beating and when they stop beating after aging in culture. In addition, the levels of glucose, glycogen, and ATP were determined to relate the concentration of these metabolites with beating and with cessation of beating. When young rat heart cells in culture are actively beating, they oxidize free fatty acids at a rate parallel with cellular ATP production. Both fatty acid oxidation and ATP production remain constant while the cells continue to beat. Furthermore, glucose is removed from the growth medium by the cells and stored as glycogen. When cultured cells stop beating, a decrease is seen in their ability to oxidize free fatty acids and to release them from their corresponding triglycerides. Concomitant with decreased fatty acid oxidation is a decrease in cellular levels of ATP until beating ceases. Midway between initiation of cultures and cessation of beating the cells begin to mobilize the stored glycogen. When the growth medium is supplemented with cortisol acetate and given to cultures which have ceased to beat, reinitiation of beating occurs. Furthermore, all decreases previously observed in ATP levels, fatty acid oxidation, and esterase activity are restored.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号