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At least 19 recordsLinked to original sources
PubMed1996

Adaptive metabolic responses in females of the fighting breed submitted to different sequences of stress stimuli.

The objectives of this study were to evaluate the stress reaction and the metabolic adaptive effort in females of the fighting breed when submitted to different manipulation sequences. Nine 4- to 8-year-old bovine fighting breed females slaughtered to establish the basal levels of different blood parameters. A study was, then, conducted to examine the metabolic response in 30 2-year-old females, divided into 3 groups of 10 animals and submitted to different manipulations in each group: restraint- "open-field" -restraint, "open-field" -restraint, and transportation-restraint- "open-field" -restraint. The basal levels of the different blood parameters found were, in general, similar to the levels for cattle given in the literature. All the manipulations resulted in increases that were statistically different (p < 0.001) from basal levels, in terms of both cortisol plasma levels and the Specie Specific Experimental Response to Stress index (SSERTS). The stress of restraint (and the prior manipulations) seemed to mask the stress associated with the open-field and transport situations. In general, animals responded to 13 of the 15 parameters examined in the various experimental manipulations.

Adaptation, Physiological↗
PubMed2001

Adult cockatiels (Nymphicus hollandicus) metabolically adapt to high protein diets.

To determine the ability of cockatiels (Nymphicus hollandicus), a granivorous avian species, to adapt metabolically to high dietary protein levels, adult males (n = 26) were fed isocaloric diets containing 11, 20, 35 or 70% crude protein (CP) for 11 mo. Throughout the trial, body weight and breast muscle weight were maintained by 11, 20 or 70% CP. The 35% CP diet resulted in significantly greater body weight (P < 0.05) and whole-body lipid content (P < 0.05) compared with the 11% CP diet. The 20% CP diet resulted in greater breast muscle mass compared with 70% CP (P < 0.05). Activity of the amino acid catabolic enzymes alanine aminotransferase, aspartate aminotransferase and arginase as well as the gluconeogenic enzyme phosphoenolpyruvate carboxykinase were significantly increased with 70% CP (P < 0.05). Serum essential amino acids, urea and uric acid were also increased with 70% CP (P < 0.05), but the magnitude of their increase was similar to that found in omnivorous chickens fed a similar diet. There was no evidence of visceral gout, articular gout or renal pathology; however liver lesion severity, and specifically liver lipogranuloma severity, was significantly increased above 11% CP (P < 0.05). We conclude that cockatiels are able to up-regulate enzymes for amino acid catabolism as well as mechanisms for nitrogen excretion in response to high dietary protein levels, and that high dietary protein levels are not associated with kidney dysfunction in this avian species.

Adaptation, Physiological↗
PubMed1996

Chronic hypoxia induces adaptive metabolic changes in neonatal myocardium.

The effect of chronic hypoxia on neonatal myocardial metabolism remains undefined. With a new neonatal piglet model, we determined changes in myocardial metabolism during global ischemia after chronic hypoxia. Five-day-old piglets (N = 30) were randomly assigned to two groups and exposed to an atmosphere of 8% oxygen or to room air for 28 days before they were killed. Left ventricular myocardium was then analyzed at control and at 15-minute intervals during 60 minutes of global normothermic ischemia to determine high-energy phosphate levels, glycogen stores, and lactate accumulation. Time to peak ischemic myocardial contracture was measured with intramyocardial needle-tipped Millar catheters as a marker of the onset of irreversible ischemic injury. Results showed an initially greater level of myocardial adenosine triphosphate in the hypoxic group (27 +/- 1.2 vs 19 +/- 1.8 micromol/gm dry wt, p = 0.001) and a delay in adenosine triphosphate depletion during 60 minutes of global ischemia compared with the control group. Initial energy charge ratios (1/2 adenosine diphosphate + adenosine triphosphate/adenosine monophosphate + adenosine diphosphate + adenosine triphosphate) were also greater in the hypoxic group (0.96 +/- 0.01 vs 0.81 +/- 0.04, p = 0.01) and remained so throughout global ischemia. Initial glycogen stores were greater in the hypoxic group (273 +/- 13.3 vs 215 +/- 14.7 micromol/gm dry weight, p = 0.02) when compared with the control group. Lactate levels in the hypoxic group were initially higher (19.1 +/- 6.4 vs 8.9 +/- 3.1 micromol/gm dry weight, p = 0.001) compared with control levels and remained elevated throughout 60 minutes of ischemia. Time to peak ischemic contracture was prolonged in the hypoxic group (69.5 +/- 1.8 vs 48.9 +/- 1.4 minutes, p = 0.001) compared with the controls group. These data show that chronic hypoxia results in significant myocardial metabolic adaptive changes, which in turn result in an improved tolerance to severe normothermic ischemia. These beneficial effects are associated with elevated baseline glycogen storage levels and an accelerated rate of anaerobic glycolysis during ischemia.

Animals↗
PubMed1990

Some aspects of metabolic adaptations in lipid metabolism during starvation are mimicked by epinephrine in rat adipocytes.

1. The effects of fasting on the neutral lipid synthesis to insulin and/or epinephrine in isolated fat cells have been examined using [1-14C]glucose. 2. The ability of adipocytes from starved rats to synthesize fatty acids from both labeled substrates was markedly diminished compared to adipocytes from control rats. 3. The response of lipogenic stimulation to insulin at all concentrations tested was greatly diminished in adipocytes from 24 hr starved rats. 4. [1-14C]glucose utilization rates in the absence or in the presence of insulin were not significantly different in adipocytes from 24 hr starved rats as compared with control adipocytes, although basal and insulin stimulated glyceride-glycerol synthesis were significantly higher in starved adipocytes. 5. Epinephrine acutely inhibited [1-14C]acetate incorporation into fatty acids for insulin-stimulated lipogenesis in control adipocytes, in contrast, this lipolytic agent strongly increased [1-14C]glucose conversion to triacylglycerols. 6. In both cases, the differences in lipid synthesis capacities found in both nutritional states were abolished by epinephrine.

Acetates↗
PubMedDate not supplied

[Mechanism of metabolic adaptation].

The paper presents results of investigations on some mechanisms of metabolic adaptation in mammals. There are four sections in the tissue metabolic system of acid-base homeostasis: polyamines as factors of metabolic adaptation; significance of carbon dioxide for metabolic response formation in hypobiosis; polyamines metabolism in hypobiosis. Peculiarities of intermediate metabolism have been analyzed in animal tissues under the changes in H+, CO2 and HCO3- concentrations. Basing on a new interpretation of the experimental data and detected regularity in the metabolism, conclusion on the existence of a new acid-base homeostasis system in the tissues has been made. The results of polyamines metabolism investigations in the mammals under the stress have been described. The experimental data make us to believe that changes in polyamines synthesis and ODC activity in particular, is a part of stereotype nonspecific response to any stress impacts and one of the factors of cell metabolic adaptation. Some new data on mechanisms of formation and control of metabolic status of animals in the natural and artificial hibernation have been presented. The key idea is that in the state of hypobiosis the carbon dioxide (HCO3-) appears as a regulatory factor of metabolic adaptation, which is able to realize its action directly via affecting numerous biochemical events. The participation of polyamines in adaptive metabolic response to hybernation factors is suggested. Some peculiarities of ornithine decarboxilase and transglutaminase activity during the different stages of genuine and artificial hypobiosis have been demonstrated.

Acid-Base Equilibrium↗
PubMed1994

Metabolic adaptation of renal carbohydrate metabolism. V. In vivo response of rat renal-tubule gluconeogenesis to different diuretics.

We have studied the effects of the diuretics mersalyl, furosemide and ethacrynic acid on renal gluconeogenesis is isolated rat-kidney tubules and on the activities of the most important gluconeogenic and glycolytic enzymes in both fed and fasted rats. Mersalyl (15 mg.kg-1 animal weight) significantly decreased the rate of gluconeogenesis in well-fed rats (68%) as well as in 24 and 48-h fasted ones (33 and 37% respectively). This inhibition occurred when lactate, pyruvate, glycerol or fructose were used as substrates. Ethacrynic acid at a dose of 50 mg.kg-1 animal weight provoked a transient inhibition of renal glucose production by almost 20% but only in fed rats with lactate as substrate, whereas the same dose of furosemide did not affect this metabolic pathway. Parallel to these changes, mersalyl caused a significant inhibition in the maximum activity of the most important gluconeogenic enzymes, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase and glucose 6-phosphatase, in both fed and fasted rats. Neither ethacrynic acid nor furosemide produced any variations in the activities of these enzymes. The activity of the glycolytic enzymes phosphofructokinase and pyruvate kinase was not modified by these diuretics. Nevertheless, the activity of the thiol-enzyme glyceraldehyde 3-phosphate dehydrogenase was severely inhibited by mersalyl and to a lesser extent by the other diuretics. This inhibition was higher in fasted than fed rats. Hence, we conclude that the inhibitory effect of mersalyl on renal gluconeogenesis is due, at least partly, to a decrease in the flux through the gluconeogenic enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Metabolic adaptation of renal carbohydrate metabolism. IV. The use of site-specific liver gluconeogenesis inhibitors to ascertain the role of renal gluconeogenesis.

The in vitro and in vivo effects of several different inhibitors of carbohydrate metabolism have been studied. The in vitro addition of 5-methoxyindole-2-carboxylic acid (MICA), pent-4-enoic acid, and quinolinic acid to the perfusion medium significantly inhibited liver gluconeogenesis in 48-hour-starved rats (100% inhibition when MICA and quinolinic acid were added at 0.8 and 2.4 mM, respectively). In vivo the level of inhibition varied greatly depending upon whether MICA was administered by intragastric tube or intraperitoneal injection. In all cases the inhibitory capacity of MICA on liver gluconeogenesis was significantly higher when injected intraperitoneally. On the other hand, the administration of MICA produced a significant, dose-dependent, increase in renal gluconeogenesis in both fed and 48-hour-starved rats, more so when the inhibitor was administered by intraperitoneal injection.

Animals↗
PubMed2005

Adaptative metabolic response of human colonic epithelial cells to the adverse effects of the luminal compound sulfide.

Hydrogen sulfide (H(2)S), a bacterial metabolite present in the lumen of the large intestine, is able to exert deleterious effects on the colonic epithelium. The mechanisms involved are still poorly understood, the reported effect of sulfide being its capacity to reduce n-butyrate beta-oxidation in colonocytes. In this work, we studied both the acute effect of the sodium salt of H(2)S on human colonic epithelial cell metabolism and the adaptative response of these cells to the pre-treatment with this agent. Using the human colon carcinoma epithelial HT-29 Glc(-/+) cell model, we found that the acute effect of millimolar concentrations of NaHS was to inhibit l-glutamine, n-butyrate and acetate oxidation in a dose-dependent manner. Using micromolar concentrations of NaHS, a comparable effect but largely reversible was observed for O(2) consumption and cytochrome c oxidase activity. Pre-treatment with 1 mM NaHS induced several adaptative responses. Firstly, increased lactate release and decreased cellular oxygen consumption evidenced a Pasteur-like effect which only partly compensated for the altered mitochondrial ATP production. Thus, a decrease in the proliferation rate with a constant adenylate charge was observed. Secondly, in these pre-treated cells, NaHS induced a hypoxia-like effect on cytochrome c oxidase subunits I and II which were decreased. Thirdly, a mild uncoupling of mitochondrial respiration possibly resulting from an increase of UCP 2 protein was observed. The NaHS antimitotic activity was not due to cellular apoptosis and/or necrosis but to a proportional slowdown in all cell cycle phases. These results are compatible with a metabolic adaptative response of the HT-29 colonic epithelial cells to sulfide-induced O(2) consumption reduction which, through the maintenance of a constant energetic load and an increased mitochondrial proton leak, would participate in the preservation of cellular viability.

Adaptation, Physiological↗
PubMed1989

Metabolic adaptation of the renal carbohydrate metabolism. III. Effects of high protein diet on the gluconeogenic and glycolytic fluxes in the proximal and distal renal tubules.

The adaptive response of renal metabolism of glucose was studied in isolated rat proximal and distal renal tubules after a high protein-low carbohydrate diet administration. This nutritional situation significantly stimulated the gluconeogenic activity in the renal proximal tubules (about 1.5 fold at 48 hours) due, in part, to a marked increase in the fructose 1,6-bisphosphatase (FBPase) and phosphoenolpyruvate carboxykinase (PEPCK) activities. In this tubular fragment, FBPase activity increased only at subsaturating fructose 1,6-bisphosphate concentration (30% at 48 hours) which involved a significant decrease in the Km (31%) for its substrate without changes in the Vmax. This enzymatic behaviour is probably related to modifications in the activity of the enzyme already present in the renal cells. Proximal PEPCK activity progressively increased at all substrate concentrations (almost 2 fold at 48h of high protein diet) which brought about changes in Vmax without changes in Kim. These changes are in agreement with variations in the cellular concentration of the enzyme. Neither gluconeogenesis nor the gluconeogenic enzymes changed in the distal fractions of the renal tubules. On the other hand, a high protein diet did not apparently modify the glycolytic ability in any fragment of the nephron, although a significant increase in the phosphofructokinase (PFK) and pyruvate kinase (PK) activities was found in the distal renal tubules. This short term regulation involved a significant decrease from 24 hours in the Km value of distal PFK (almost 40%) without changes in Vmax. The kinetic behaviour of distal PK was mixed. In the first 24h after high protein diet a significant decrease in the Km for phosphoenolpyruvate was found (30%) without variation in the Vmax, however during the second 24 hours the activity of this glycolytic enzyme increased significantly (almost 1.3 fold) without modifications in its Km value. On the contrary, this nutritional state did not modify the kinetic behaviour of any glycolytic enzyme in the proximal regions of the renal tubules.

Animals↗
PubMed2000

Metabolic adaptations to environmental changes in Caenorhabditis elegans.

Metabolic adaptations to environmental changes were studied in Caenorhabditis elegans. To assess adjustments in enzyme function, maximum activities of key enzymes of main metabolic pathways were determined. After a 12 h incubation at varying temperatures (10, 20 degrees C) and oxygen supplies (normoxia or anoxia), the activities of the following enzymes were determined at two measuring temperatures in tissue extracts: lactate dehydrogenase (LDH; anaerobic glycolysis), 3-hydroxyacyl-CoA-dehydrogenase (HCDH; fatty acid oxidation), isocitrate dehydrogenases (NAD-IDH, NADP-IDH; tricarboxylic acid cycle) and isocitrate lyase (ICL; glyoxylate cycle). Incubation at 20 degrees C induced a strong increase in maximum LDH activity. Anoxic incubation caused maximum HCDH and NADP-IDH activities and, at 10 degrees C incubation, LDH activity to increase. Maximum NAD-IDH and ICL activities were not influenced by any type of incubation. In order to study the time course of metabolic adaptations to varying oxygen supplies, relative quantities of free and protein-bound NADH were determined in living C. elegans using time-resolved fluorescence spectroscopy. During several hours of anoxia, free and protein-bound NADH showed different time courses. One main result was that just at the moment when the protein-bound NADH had reached a constant level, and the free NADH started to increase rapidly, the worms fell into a rigor state. The data on enzyme activity and NADH fluorescence can be interpreted on the basis of a two-stage model of anaerobiosis.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1987

Basal metabolic rate of Indian men: no evidence of metabolic adaptation to a low plane of nutrition.

Basal metabolic rate (BMR) was measured in 58 men of a rural Indian population who had low body weight and body fat stores. Comparisons of subgroups of subjects of different socio-economic status and different nutritional status showed no evidence of differences in BMR when corrected for differences in body weight and body fat content. This suggests that metabolic adaptation did not account for differences in absolute BMR between subgroups of this population. The BMR values agreed well with values predicted by equations based on BMR measurements in Asian men of higher body weight, but were below values predicted by the new FAO/WHO/UNU prediction equations by an average of 12.1 per cent (P less than 0.0001). This overprediction could be a reflection of allometric or climatic influences on BMR rather than evidence for metabolic adaptation to a low plane of energy nutrition.

Adaptation, Physiological↗
PubMed1988

Metabolic adaptation of the renal carbohydrate metabolism. I. Effects of starvation on the gluconeogenic and glycolytic fluxes in the proximal and distal renal tubules.

The influence of starvation on renal carbohydrate metabolism was studied in the proximal and distal fragments of the nephron. Starvation induced a double and opposite adaptation mechanism in both fractions of the renal tubule. In renal proximal tubules, the gluconeogenic flux was stimulated progressively during a period of 48 hours of starvation (2.15 fold), due, in part, to a significant increase in the fructose 1,6-bisphosphatase and phosphoenolpyruvate carboxykinase activities although with different characteristics. Fructose 1,6-bisphosphatase activity from this tubular fragment increased only at subsaturating subtrate concentration (68%) which involved a significant decrease in the Km (35%) for fructose 1,6-bisphosphate while there was no change in Vmax. This behaviour clearly indicates that it is related to modifications in the activity of the preexistent enzyme in the cell. Proximal phosphoenolpyruvate carboxykinase activity increased proportionally at both substrate concentrations (86 and 89% respectively) which brought about changes in Vmax without changes in Km, all of which are in accordance with variations in the cellular levels of the enzyme. In the renal distal tubules, the glycolytic capacity drastically decreased throughout the starvation time. At 48 hours 65% of inhibition was shown. We have found a short term regulation of phosphofructokinase activity by starvation which involves an increase in Km (2.2 fold) without changes in Vmax, as a result of these kinetic changes, an inactivation of phosphofructokinase was detected at subsaturating concentration of fructose 6-phosphate. On the contrary, this nutritional state did not modify the kinetic behaviour of renal pyruvate kinase. Finally, neither proximal glycolytic nor distal gluconeogenic capacities and related enzymes activities were changed during starvation.

Animals↗
PubMed1983

Metabolic adaptations of the fetus and newborn.

During the perinatal period metabolic adaptations take place which insure that substrates for energy production and growth are available in the immediate postnatal period. The fetus receives a constant infusion of glucose, fatty acids and protein by the placenta. Late in gestation the accumulation of storage fuels such as glycogen and adipose tissue anticipate the abrupt cessation of substrate supply from the placenta at the time of birth. Postnatally an increase in endogenous production of glucose in the form of glycogenolysis and gluconeogenesis become important for maintenance of glucose homeostasis. Increase utilization of fatty acids in ketone bodies as energy substrates also become important in the postnatal period. These metabolic adaptations are mediated by the development of new enzyme activities as well as by changes in hormonal millieu and substrate availability.

Animals↗
PubMed1989

Metabolic adaptation of the renal carbohydrate metabolism. II. Effects of a high carbohydrate diet on the gluconeogenic and glycolytic fluxes in the proximal and distal renal tubules.

The effects of a high carbohydrate diet on the renal gluconeogenic and glycolytic capacities and on the activities of the main enzymes of the carbohydrate metabolism, fructose 1,6-bisphosphatase, phosphofructokinase and pyruvate kinase have been studied. These parameters have been analysed in two separate and isolated fractions of the renal tubule, the proximal convoluted (PCT) and the distal convoluted (DCT) zones. The results presented in this study show a rapid adaptation capacity of the kidney in response to the high amount of dietary carbohydrate, which are characterized by a decrease in the glucose production and fructose 1,6-bisphosphatase activity in the proximal tubules, and an increase in the glycolytic flux and phosphofructokinase and pyruvate kinase activities in the distal tubules. The changes in these enzyme activities took place only at subsaturating substrate concentrations and not at maximum velocity which suggest that they are probably due to an allosteric and/or covalent modifications and so, they are independent of variations in the cellular levels of the enzymes.

Animals↗
PubMed2003

Removal of organic pollutants and metabolic adaptation of microorganisms by micro-aeration.

Aerobic systems are high rate processes for wastewater treatment, but they consume much power for aeration. Several low-cost anaerobic systems have been developed for mid- and low-income countries. The removal efficiencies of nutrients, particulate matter, and pathogens are not satisfactory for the anaerobic systems. Micro-aeration is a type of low-cost aerobic application which enhances oxygen transfer through water surface. Trickling was found the most efficient method of micro-aeration and batch experiments were performed to evaluate the effectiveness. When soluble organic carbon was removed, ORP7 (redox potential rectified to pH at 7) were around -120 or +260 mV. When soluble organic carbon increased due to organic overload, ORP7 was around +30 mV. At +30 mV, carbon fraction of biomass increased to 0.54 (higher than average value of 0.46). It was presumable that the ORP7 of -120, +260, and +30 mV were anaerobic, aerobic, and internal storage mode, respectively. Maximum reaction rate of aerobic condition was four times as high as that of anaerobic condition. At internal storage mode, the rate was halved from aerobic mode. It is concluded that microorganisms adapt the metabolic systems to conform to the redox environment, which can be evaluated by ORP. Organic overload results metabolic shift to internal storage mode which retards mineralization of organic matter.

Bacteria, Aerobic↗