Effects of the nonsteroidal anti-inflammatory drug piroxicam on energy metabolism in the perfused rat liver

• 1.1. The actions of piroxicam, a nonsteroidal and noncarboxylic anti-inflammatory drug, on the metabolism of the isolated perfused rat liver were investigated. The main purpose was to verify if piroxicam is also active on glycogenolysis and energy metabolism, as demonstrated for several carboxylic nonsteroidal anti-inflammatories.
• 2.2. Piroxicam increased oxygen consumption in livers from both fed and fasted rats.
• 3.3. Piroxicam increased glucose release and glycolysis from endogenous glycogen (glycogenolysis).
• 4.4. Gluconeogenesis from lactate plus pyruvate was inhibited.
• 5.5. The action of piroxicam on oxygen consumption was blocked by antimycin A, but not by atractyloside.
• 6.6. The action of piroxicam in the perfused rat liver metabolism seems to be a consequence of its action on mitochondria.
• 7.7. It can be concluded that inhibition of energy metabolism and stimulation of glycogenolysis are not specific properties of carboxylic nonsteroidal anti-inflammatory drugs.

     

Carbohydrate metabolism in several tissues of rainbow trout,Oncorhynchus mykiss,is modified during ovarian recrudescence

• 1.1. Several pathways of carbohydrate metabolism were evaluated in three different tissues—liver, gonad and kidney—of a hatchery-reared population of rainbow trout (Oncorhynchus mykiss) which characterised two different stages of their gonadal maturation, i.e. previtellogenesis and established exogenous vitellogenesis.
• 2.2. A fall in liver glycogen levels was observed during exogenous vitellogenesis. A decrease in activity of the enzymes involved in glycolysis and in the pentose phosphate shunt was also observed, suggesting that at the end of exogenous vitellogenesis the necessity of energy and reducing power has decreased compared to the situation at the onset of this period.
• 3.3. The main changes observed in gonad during vitellogenesis were the decreased activity of glycolysis and the pentose phosphate shunt as well as increased glycogen levels. The stored glycogen should be used later in association with the embryo development.
• 4.4. No major changes were observed in kidney metabolism throughout the vitellogenic process.
• 5.5. Exogenous vitellogenesis in rainbow trout is mainly associated with increased glycogen levels in the gonad and decreased metabolic activity in the liver.

     

NAD(P)H dehydrogenase from rabbit and rat liver: Purification and some properties

• 1.1. NAD(P)H dehydrogenase from rabbit liver was purified to electrophoretic homogeneity using a procedure also found applicable for the rat liver enzyme.
• 2.2. Rabbit and rat liver enzymes showed different behaviour in isoelectric focusing and different K_m values and turnover numbers.
• 3.3. Both enzymes were inhibited to similar extents by warfarin.
• 4.4. The rabbit enzyme is composed of two subunits of mol. wt 27,000 and contained 1 FAD group per subunit.
• 5.5. Some absorption and circular dichroism properties of the rat enzyme are shown.

     

Effects of high dietary methionine on activities of selected enzymes in the liver of kittens (felis domesticus)

• 1.1. Growing male kittens were fed an 18% casein diet supplemented with 2, 3, or 4% l-methionine (MET) for 6 weeks.
• 2.2. Free MET concentration in liver increased 30-fold and cystathionine two- to three-fold; the activity of adenosyl-MET transferase and cystathionase also increased but remained lower than previously found in rats.
• 3.3. Taurine concentration in liver decreased in cats fed excess MET and appeared to depend on taurine intake.
• 4.4. Alanine aminotransferase activity was high in all groups while serine dehydratase activity was very low.
• 5.5. Pyruvate kinase and malic enzyme activities which are normally low in cat liver increased after excess MET. Also, glucose 6-phosphate and 6-phosphogluconate dehydrogenases increased.
• 6.6. Cat liver metabolism showed limited adaptation to an excess dietary intake of methionine compared to that found in rats.

     

Functional groups in the social behavior of a cichlid fish,the Oscar,Astronotus ocellatus

Dummy conspecifics were presented to isolated adults of the cichlid fish Astronotus ocellatus to investigate the functional organization of cichlid social behavior. Body size and 15 dummy-elicited activities were recorded during 15 min sessions and analyzed by principal components analysis (PCA) to reveal their temporal organization. Five principal components explained almost 80% of the variation in dummy-elicited behavior, and these five factors define functional groups for

• 1.(a) investigation,
• 2.(b) attack,
• 3.(c) nesting,
• 4.(d) boldness,
• 5.(e)distress.

Nest-oriented and attack modal action patterns are not mutually inhibitory during this time frame, and biting does not appear to function exclusively during an attack on a conspecific. Comparison with previous studies of New and Old World cichlids suggests evolutionary conservation of the functional organization of social behavior.     

Effect of hibernation on liver and kidney metabolism in 13-lined ground squirrels

• 1.1. Metabolic rates and adenine nucleotide content of liver and kidney from hibernating ground squirrels were measured and compared to rats to study the biochemical adaptation to hibernation.
• 2.2. High rates of renal and hepatic gluconeogenesis were observed in squirrels, particularly from propionate and glycerol compared to rat.
• 3.3. During hibernation and starvation soluble phosphoenolpyruvate carboxykinase activity was increased in both liver and kidney.
• 4.4. Although metabolic rates are decreased during hibernation the results suggest that the enzymic complement is maintained at high activity even during torpor.

     

Evidence for extracellular deamination of adenosine in the rat heart

• 1.1. In rat heart perfused with adenosine (10⁻⁶M), dilazep (10⁻⁴M) inhibited incorporation of adenosine into nucleotides (an index of nucleoside transport and phosphorylation) to a greater extent (70%) than metabolism to inosine and uric acid (40%) and actually increased the recovery of inosine to 30% of the adenosine infused.
• 2.2. Extrapolating for complete inhibition of transport suggested that 60% of adenosine metabolism was intracellular and 40% extracellular.
• 3.3. Static incubations of atria also gave an estimate for extracellular metabolism of 40%.
• 4.4. Adenosine deaminase was localised by immunocytochemistry to the extracellular surface of endothelial cells of small coronary arteries.
• 5.5. Extracellular deamination may explain the lack of effect of nucleoside transport inhibitors on responses to adenosine in rat heart.

     

Metabolism of benzo[a]pyrene and persistence of DNA adducts in the brown bullhead (Ictalurus nebulosus)

• 1.1. The in vitro metabolism of [³H]benzo[a]pyrene (BP) and [¹⁴C]benzo[a]pyrene-7,8-dihydrodiol (BP-7,8-diol) by liver of brown bullhead (Ictalurus nebulosus) was characterized, as was the formation and persistence of BP-DNA adducts in vivo.
• 2.2. Compared to rat liver microsomes, bullhead liver microsomes produced relatively larger amounts of BP-7,8-diol (predominantly the [−] enantiomer) and smaller amounts of BP-4,5-diol.
• 3.3. BP phase I metabolites were efficiently converted by freshly isolated bullhead hepatocytes to conjugates, predominantly glucuronides.
• 4.4. BP-7,8-diol was metabolized by hepatocytes 4-fold more rapidly than was BP and was converted to approximately equal amounts of glucuronides, glutathione conjugates and sulfates.
• 5.5. BP-DNA adducts formed in bullhead liver with a lag time of several days and maximum adduct formation at 25–30 days. The major adduct was anti-BPDE-deoxyguanosine.

     

The energetics of shedding: Energy content of snake skin

• 1.1. The weight and energy content of sloughed skins of 92 individual snakes of 22 different species in three families were measured.
• 2.2. Weight and total energy content of shed skins were highly correlated with body weight.
• 3.3. The heat of combustion (kJ/g) of sloughed skins varied significantly among families and was higher in species having unkeeled scales than in those with keeled scales.
• 4.4. The presence of keels significantly affected weight of skins, even when skin weight is adjusted for covariance with body weight.
• 5.5. Neither body weight nor ambient temperature significantly affected the heat of combustion of sloughed skins.
• 6.6. The energy content of shed skin, expressed as a proportion of daily metabolism, decreased with ambient temperature, but the effect is minimized in large snakes.
• 7.7. Small snakes expended relatively less energy in sloughed skins than large snakes when the expenditure is expressed in terms of total daily metabolized energy.

     

Effect of polarized light on the ERG circadian rhythm in crayfish

• 1.1. Crayfish subjected to constant darkness and temperature displayed an electroretinographic circadian rhythm with both non-polarized and polarized light stimuli.
• 2.2. In the ERG circadian rhythm associated with polarized light there was an observed reduction in period and increment in both amplitude and activity: rest ratio.
• 3.3. The change from non-polarized to polarized light also produced phase advances or delays in the ERG circadian rhythm depending on the circadian time when the change was introduced.
• 4.4. Separate recording of HI and HII ERG components showed that HII is always less conspicuous and more easily saturable than HI circadian rhythm.
• 5.5. These results support that: (a) the detection of polarized light contributes to extend the differences between night and day; (b) the two structures involved in the generation of HI and HII ERG components, i.e. the rhabdom and the retinular cell, operate as two independent elements of the circadian system responsible of ERG circadian rhythm.

     

The development of thermoregulation in the marsupial brushtail possum Trichosurus vulpecula

• 1.1. The adult possums showed a circadian rhythm of body temperature with a peak in temperature around midnight and a nadir at noon.
• 2.2. The young possum within the pouch displayed a circadian rhythm with the highest temperatures during the day and the lowest in the early evening.
• 3.3. Although the body temperature of the young possum exceeded that of the mother occasionally, for the major part of the 24 hr the body temperature of the young was lower than that of the mother.
• 4.4. The young possum could maintain a steady body temperature between 140 and 167 days post partum. A circadian rhythm of temperature was observed between 157–190 days post partum.
• 5.5. All adipose tissue examined with the light and electron microscope had the morphology of white adipose tissue.

     

Erg circadian rhythm in the course of ontogeny in crayfish

• 1.1. The objective of the present work was to study the ontogeny of the ERG circadian rhythm in crayfish.
• 2.2. Long-term recordings of ERG and shielding retinal pigments position measured from the instar, the second instar, the third instar and the adult crayfish were obtained.
• 3.3. In the youngest animals (1–8 days old) an ultradian rhythm (15min-4hr periods) in the ERG amplitude was detected.
• 4.4. Older animals showed a progressive increment in the period length before they exhibited a circadian pattern. This last appeared, the first time, in 30-day-old animals and showed noticeable differences in the adult crayfish. At the same time, the crayfish began to show photomotor reflex. Later on (140-day-old crayfish) the circadian rhythm attained its final parameters.
• 5.5. The SD was used as a measure of lability in periods. The 4 hr ultradian rhythm and the 22.4 hr circadian rhythm showed the lowest SD indicating that they are the most precise period values.
• 6.6. Our results support the idea that the ERG circadian rhythm results from the coupling among high frequency (ultradian) oscillators, particularly those of 4 hr periods and that the coupling depends on the action of neurosecretions released from the sinus gland.

     

Monoclonal antibodies against rat liver mitochondrial phospholipase a2: Epitope analysis and application in western blotting

• 1.1. Eight cell-lines producing monoclonal antibodies, raised against rat liver mitochondrial phospholipase A₂, were investigated with respect to epitope-recognition. It was shown that all antibodies tested were directed to an identical epitope.
• 2.2. This epitope is a conformational one, since treatment of phospholipase A₂ with the reducing agent dithiothreitol lowered the antibody binding significantly.
• 3.3. To increase sensitivity, Western blot analyses have to be performed on protein samples lacking dithiothreitol or β-mercaptoethanol. The conditions described in this report allow the detection of the phospholipase A₂ in rat liver homogenates.
• 4.4. When rat liver mitochondrial phospholipase A₂ was purified by Ultrogel AcA 54 gelfiltration, a nearly homogeneous protein preparation was obtained, as judged by SDS-PAGE. Western blot analysis of this preparation, however, clearly indicated the phospholipase A₂ to correspond to a hardly visible protein band.

     

The metabolic output of avian (Sturnus vulgaris,Calidris alpina) adipose tissue liver and skeletal muscle: Implications for BMR/body mass relationships

• 1.1. The oxygen uptake rate of avian adipose tissue, liver and skeletal muscle slices were measured.
• 2.2. The energy consumption of fat was less than one tenth that of liver and muscle.
• 3.3. Thus, interspecific allometric equations for the prediction of basal metabolic rate from body mass will not be accurate throughout the avian annual cycle unless changes in body composition are taken into account.

     

Influence of handling and/or anaesthesia on stress response in rainbow trout. Effects on liver primary metabolism

• 1.1. The overall effect of handling, anaesthesia and sham injection on some blood metabolites, liver glycogen and several key enzymes involved in liver carbohydrates and nitrogen metabolism was studied in rainbow trout. In addition, the possible role of anaesthesia (MS222) itself as a stress-inductor or suppressor was also studied.
• 2.2. Stress resulted in hyperglycaemia and initially in liver glycogen depletion, as well as increasing plasma amino acid levels.
• 3.3. Glycogen stores subsequently recovered while amino acid concentration fell.
• 4.4. These changes seemed to correlate with the increased activity of liver fructose 1,6-bisphosphatase, glucose 6-phosphate dehydrogenase, alanine aminotransferase and glutamate dehydrogenase, thus supporting the hypothesis that gluconeogenic flux from amino acids increases in stressed trouts.
• 5.5. Anaesthesia, under the same experimental conditions, did not seem to mediate in stress production, but rather resulted in stress suppression.

     

Effect of methyl methacrylate on mitochondrial function and structure

• 1.1. Treatment of isolated rat liver mitochondria with methyl methacrylate (MM) produced membrane disruption as evidenced by the release of citrate synthase, and changes in the ultrastructure of mitochondria.
• 2.2. At concentration 0.1%, MM uncoupled oxidative phosphorylation as evidenced by stimulation of state 4 respiration supported either by pyruvate plus malate or succinate (+rotenone) and ATP-ase activity in intact mitochondria.
• 3.3. At concentration 1% MM stimulated ATP-ase activity in intact mitochondria and succinate (+rotenone) oxidation at state 4 and was without effect on this substrate oxidation at state 3.
• 4.4. MM inhibited pyruvate plus malate oxidation either at state 3 or in the presence of uncoupling agents.
• 5.5. MM inhibited the NADH oxidase of electron transport particles at a concentration which failed to inhibit either succinic oxidase or the NADH-ferricyanide reductase activity.
• 6.6. The data presented suggest that in the isolated mitochondria MM inhibits NADH oxidation in the vicinity of the rotenone sensitive site of complex I.
• 7.7. The general conclusion is that MM may block an electron transport and to uncouple oxidative phosphorylation in rat liver mitochondria. The overall in vitro effect would be to prevent ATP synthesis which could result in cell death under in vivo conditions.

     

Variations in tissue reserves,plasma metabolites and pancreatic hormones during fasting in immature carp (Cyprinus carpio)

• 1.1. Immature carp were subjected to 2-month fasting periods. Mobilization of reserves in liver and muscle, and the energy contribution of each reserve were studied. Changes in plasma glucose, amino acids, insulin and glucagon levels were determined throughout the experiment.
• 2.2. No changes were observed in plasma glucose, insulin or glucagon at 19 days of fasting, but plasma amino acids increased. At 50 days of fasting, both plasma glucagon and amino acids increased, liver glycogen decreased and muscle proteolysis began.
• 3.3. Between 50 and 67 days of fasting, plasma glucose and insulin decreased significantly, while glucagon and amino acids continued to increase. Strong muscular proteolysis was observed while liver glycogen stabilized.
• 4.4. The contribution of each reserve in liver and muscle to energy production throughout fasting is considered.

     

Carbohydrate metabolism during osmoregulation in Chasmagnathus granulata dana, 1851 (crustacea,decapoda)

• 1.1. Since glucose is one of the main energetic substrates for general metabolic processes in crustaceans, analysis of carbohydrate levels can furnish information on the energy metabolism of intact animals during osmoregulation.
• 2.2. Different groups of Chasmagnathus granulata were transferred to different salinities (0 and 40%), and the glucose and glycogen concentrations in blood, gills, muscle and hepatopancreas were determined at the beginning of the experiment and 24, 72, 168 and 360 hr after the salinity changes.
• 3.3. Differences in tissues carbohydrate levels were observed between summer and winter, that reflected differences in reserve mobilization.
• 4.4. In the summer, hypo- and hyperosmotic shocks induced an increase in carbohydrate levels in almost all tissues studied, indicating gluconeogenesis.
• 5.5. In the winter, a carbohydrate mobilization occurred only in the gills and hepatopancreas after both osmotic shocks.
• 6.6. Thus, the substrate reserve used for energy production required for osmoregulation seems to be dependent on the season and tissues.

     

The energy burden of the bopyrid parasite Argeia pauperata (Crustacea,isopoda) on the grass shrimp Crangon franciscorum (Crustacea,crangonidae)

• 1.1. The relationship between host and parasite rates of energy metabolism was used to estimate the energy burden of Argeia pauperata on its host Crangon franciscorum.
• 2.2. Respiration rates of the host were not significantly affected by the parasite even though the caloric turnover rate of the parasite was more than three times that of the host.
• 3.3. The ratios of both energy expenditure and size of the parasite to those of the host were positively correlated with host size.