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L Arola

Publications and source records attributed to L Arola.

At least 55 records · Page 3Linked to original sources
PubMed1989

Effects of a high lipidic diet on murine energetic reserves in food deprivation.

Female mice were fed for one month either control or cafeteria diets. Then they were subjected to food deprivation for up to 36 hours and their weight loss, tissue lipid, glycogen and protein were determined together with their plasma glycose, amino acids, urea, lipoproteins and ketone bodies. Cafeteria mice were able to cope with prolonged starvation with altered plasma composition and important loss of lipids and protein, sparing to a certain degree their glucose and amino acids. Control-fed mice, however, showed a intense ketosis and significant losses of nitrogen. The results obtained showed a higher ability of cafeteria mice to handle and use lipids, that evolves in a better suitability to resist food deprivation with less extensive alterations in their fuel and nitrogen homeostasis.

Animals↗
PubMed1989

Characterization of the inhibition effect induced by nickel on glucose-6-phosphate dehydrogenase and glutathione reductase.

Kinetic characterization of the inhibition effect of nickel on glucose-6-phosphate dehydrogenase (EC 1.1.1.49) (G-6-PD) and glutathione reductase (GR; EC 1.6.4.2) from Saccharomyces cerevisiae was made. The effect of nickel on G-6-PD activity is consistent with a mixed-type inhibition pattern, with a competitive character, since the inequality ki,int greater than ki,slope shows an inverse relation between varied substrate concentrations and fractional inhibition. An inhibition effect of nickel on GR activity, when NADPH is the varied substrate, is also consistent with a mixed-type inhibition pattern. However, pure competitive inhibition is found on GR reaction when oxidized glutathione is the varied substrate. This investigation shows the highest sensibility of GR before the inhibitory effect of nickel, in agreement with the experimental values of inhibition constants found in this study, where constants related to the GR system are lower than the ones of the G-6-PD system.

Glucosephosphate Dehydrogenase↗
PubMed1989

Alterations of energy metabolism induced by hexadecane in mice.

Two groups of young male OF-1 mice were fed for 60 days with cafeteria or, as controls, with standard pellet diet respectively. At that time, both groups were daily treated with hexadecane (HDK) on the skin. HDK induced a drastic body weight loss much higher in cafeteria than control mice. White adipose tissue were exhausted after 4 days of treatment in controls but not after 10 days in cafeteria ones. HDK resulted in mobilization of liver glycogen in both groups while muscle glycogen decreased slightly in the end. Hexadecane treatment did not result in massively enhanced nitrogen metabolism, as the actual oxidation of amino acids decreased considerably as indicated by the low levels of plasma urea. The results could be explained by powerful and lasting effects of hexadecane on thermogenesis and metabolic reserve balance. The use of this material for pharmacological manipulation of body weight appeared difficult.

3-Hydroxybutyric Acid↗
PubMed1989

Brown adipose tissue (Na+-K+)-ATPase activity and substrate uptake during the breeding cycle of rats.

Brown adipose tissue (Na+-K+)-ATPase activity, in vitro glucose and 2-aminoisobutyric acid uptake, as well as mitochondrial GDP-binding and succinate dehydrogenase activity were determined in order to study the relationship between these parameters and the thermogenic status. Analysis were carried out on control animal, pregnant rats, dams and pups during lactation, GDP-binding, (Na+-K+)-ATPase and glucose uptake were found to be decreased in brown adipose tissue from pregnant rats and dams, and increased in pups, 2-aminoisobutyric acid uptake was only increased in pups, but no changes were observed in the other experimental groups tested. GDP-binding and (Na+-K+)-ATPase activity showed a parallelism which suggests that the enzyme is a good index of thermogenic status of the animal.

Adipose Tissue, Brown↗
PubMed1989

Initial permeability of the 19-day foetus to nickel.

The administration of 63NiCl2 to 19-day pregnant rats produced a limited transfer of nickel to the foetus. An experimental model based on the incubation of the conceptuses still connected to the maternal organism resulted in an appreciable net transfer of nickel through the amniotic membranes. The placenta retained a significant amount of radioactive nickel as did the lining of the uterine wall. The circulation of nickel through the foetus following the direction maternal blood----placenta----foetus----amniotic membranes----endometrium----maternal venous blood, is postulated. This transfer could provide an additional protection to placental barrier against metal toxicity.

Animals↗
PubMed1989

Zn(II), Cd(II) and Cu(II) interactions on glutathione reductase and glucose-6-phosphate dehydrogenase.

Kinetic characterization of the inhibition effects of Cd(II), Cu(II) and Zn(II) on glutathione reductase (GSSGR; EC 1.6.4.2.) and glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) from Saccharomyces cerevisiae was made. No inhibition effect was found with Zn(II) on these enzymatic systems. The effect of Cd(II) (up to 0.16 mM) and Cu(II) (up to 0.008 mM) on GSSGR activity is consistent with a pure competitive inhibition or an uncompetitive pattern, when the varied substrate is the oxidized glutathione or the NADPH, respectively. Only Cd(II) (up to 1.0 mM) showed an inhibition effect on G6PD system, which is consistent with a mixed-type inhibition pattern. When NADP+ changes over an extensive range of concentration, the inhibition effect shows an uncompetitive character. Furthermore, when G-6-P is the varied substrate, the character of the mixed-type inhibition is competitive.

Binding, Competitive↗
PubMed1988

In vitro glucose and 2-aminoisobutyric acid uptake by rat interscapular brown adipose tissue.

The dependence upon substrate and insulin concentrations, as well as on sodium and potassium concentrations in the medium of the uptake of glucose and 2-aminoisobutyric acid, was determined for fragments of brown and white adipose tissues incubated in vitro. Brown adipose tissue showed a high capacity for glucose uptake at high glucose concentrations, this uptake being dependent on both glucose and insulin concentration. White adipose tissue showed much more limited uptake capabilities. The presence of Na+ and K+ had little effect on the uptake. The uptake of 2-aminoisobutyric acid was similar in both adipose tissues, being enhanced by physiological levels of insulin and depressed by ouabain. This amino acid transport was dependent on Na+ and K+ concentrations, and the overall transporting capability was two to three orders of magnitude lower than that for glucose. It was concluded that amino acids could not play a significant role as bulk thermogenic substrates for brown adipose tissue, as their transporters lack the plasticity of response to high substrate and insulin concentrations which characterize brown adipose tissue uptake of glucose.

Adenosine Diphosphate↗
PubMed1988

Some pitfalls and considerations of plasma ammonia estimation.

Several approaches to the estimation of plasma ammonia have been tested and compared: indophenol, Nessler, iodometric techniques were studied as well as enzymatic spectrophotometric and radiometric methods. Their lower safe limits of estimation were determined and it was found that most of them were not viable for plasma estimations because of its very low ammonia levels. The need for a concentration/purification step and the lack of repetability in this phase at very low concentrations, made very unreliable the utilization of all methods studied except for the enzymatic radiometric method tested that was barely usable for plasma ammonia estimations.

Ammonia↗
PubMed1988

Combined pregnancy and starvation effects on rat tissue iron, zinc and copper contents.

The essential metal copper, zinc and iron content in starved virgin and pregnant rat tissue has been studied. The copper content of the whole rat, which was actually increased in pregnant rats, decreased in starved pregnant rats. The differences were significant in 19-day pregnant rats. The total copper content of the conceptus was not affected by starvation. Iron distribution and net tissue content showed the same pattern as that of copper. With regard to zinc, however, there was a decrease of its content associated with starvation in rat tissue. This decrease was statistically significant on the 21st day of gestation both in the mother and in fetuses, which marks a difference compared with the copper-iron pattern. It must be pointed out, however, that--with the significant exception of zinc--the maternal stores of the metals are enough to supply the fetus during starvation despite significant reductions in the maternal reserves.

Animals↗
PubMed1988

Glutamine and ammonium handling by anaesthetized rats.

The infusion of ether anesthaetized rats with 0.2 M (1 mmols in total) ammonium acetate or glutamine were compared with the infusion of 0.2 M NaCl. The levels of circulating glucose, amino acids, lactate, urea and ammonium were measured as well as liver glycogen and tissue amino acids and the liver and muscle activities of carbamoyl phosphate synthetases I and II, glutamate dehydrogenase, glutamine synthetase and adenylate deaminase. Neither treatment altered the glucose and glycogen homeostasis. The infusion of ammonium did not result in increases in circulating ammonium, but resulted in increased circulating urea after a short delay; the infusion of glutamine resulted also in urea production but much later on. Glutamine infusion also resulted in increased tissue free amino-acid levels. There was little alteration in enzyme activities, except for decreased glutamine synthetase and adenylate deaminase activity in muscle of glutamine-infused rats and higher tissue carbamoyl phosphate synthetase II. The results agree with a fast removal of infused ammonium, and maintenance of glutamine, with their channeling towards urea production at a rate comparable with that of infusion, that did not alter significantly the homeostasis of the experimental animals.

AMP Deaminase↗
PubMed1988

Rapid detoxification of infused ammonium by the anesthetized rat.

Anaesthetized rats were given an i.v. overload of 200 mmoles of ammonium acetate. Plasma ammonium levels were not altered for up to 20 minutes after the end of the infusion. The load of ammonium, however, increased the overall non-protein nitrogen content of circulating plasma, as for the increase in urea and amino acids (alanine, phenylalanine, aspartate + asparagine and glutamate + glutamine). The activities of glutamine synthetase was found increased in liver, muscle and kidney; and glutamate dehydrogenase increased in liver and decreased in muscle and kidney. Adenylate deaminase decreased in all the studied tissues. The fast enzyme and plasma metabolite adaptations to ammonium overload were all in the sense of favoring the incorporation of ammonium into amino acids (later into urea) as well as to avoid their deamination, thus effectively removing the excess ammonium from the bloodstream.

AMP Deaminase↗
PubMed1987

Combined effects of pregnancy and Lewis lung carcinoma bearing upon essential metal tissue content in inbred mice.

The essential metal (Cu, Zn, Fe, Ca, Mg, Na and K) tissue content in Lewis-lung-carcinoma-bearing mice was compared with that of pregnant mice as well as with controls and with mice both pregnant and cancerous. All comparisons were done on day 17 after inoculation/Impregnation on C57BL/6 age-matched female mice. Despite unchecked tumour growth and metastasizing ability, pregnancy effectively prevented the tissue-wasting effect of the tumour. The economy of all the essential metals studied followed practically the same pattern. The combined tumour-bearing and pregnancy situation was much closer to that of pregnancy than to the tumour-bearing alone, either at individual tissue concentration level or at that of the whole animal, in the maternal tissue and metal stores and tissue concentrations in front of the cachexic effect of tumour-bearing. Neither fetal nor tumour growth nor their metal content were impaired by the presence of the tumour/concepta. The maternal processes that allow for a higher fetal uptake of substrates seem to increase--at least in the case of iron--the ability of the tumour to accumulate some metals.

Animals↗
PubMed1987

Essential metal balance and retention during the second half of pregnancy in the rat.

The daily copper, zinc, iron, magnesium, calcium, sodium and potassium retention from the diet in rats during the second half of pregnancy have been determined and compared with those of adult virgin male and female rats. Pregnant rats had higher mean magnesium and potassium daily retentions than virgin females. The retention of essential metals changed along the second half of pregnancy towards lower values for copper and magnesium and higher ones for potassium. The net absolute metal retention followed the same trends. All other metals studied showed little global differences versus controls without clearly identifiable trends. The results suggest that metal retention is an adaptative element in maintaining the pregnant rat's metal supply, as the considerable metal retention in the first half of pregnancy is modulated in the second half according to the actual needs of the maternofetal unit.

Animals↗
PubMed1987

(Na+-K+)-ATPase activities in rat tissues during pregnancy.

(Na+-K+)-ATPase activities of liver, hind leg skeletal muscle, brain, perirenal white adipose tissue, interscapular brown adipose tissue and blood as well as placenta, fetal liver and fetal blood were determined in virgin rats and pregnant rats on days 12, 19 and 21 of gestation in order to evaluate its relative contribution either to metabolite transport processes or/and to thermogenesis during pregnancy. No changes were found in (Na+-K+)-ATPase activity in liver, blood and white adipose tissue in pregnant rats versus controls. (Na+-K+)-ATPase activity from muscle, brain and interscapular brown adipose tissue decreased during pregnancy and placenta showed an increase of (Na+-K+)-ATPase on day 21 of gestation in respect to day 12. No significant changes were observed either in fetal liver or fetal blood.

Adipose Tissue↗
PubMed1987

Serum protein changes in cafeteria mice induced by starvation.

Serum protein changes in cafeteria and control mice induced by starvation have been studied. Animals were subjected to food deprivation at 0, 3, 6, 9, 12, 18, 24 or 36 hours. Results show a more stabilized situation in cafeteria mice than controls particularly in protein metabolism. Serum protein composition changed very little during starvation, suggests a lower protein and amino acid catabolism induced by the high adaptation to consume lipids.

Animals↗
PubMed1987

Essential metal status of rat lactating dams.

The tissue levels of copper, iron, zinc, magnesium and calcium in lactating rat dams from the day of parturition to the post-weaning period have been studied. The data obtained suggests that the metallic status of the dams is well maintained during lactation despite the heavy losses through the milk to their pups. In this period, the dam is also able to refill her own tissue metal stores, partly depleted during pregnancy, probably through higher intake/retention of the metals from the diet.

Animals↗
PubMed1986

Effects of lactation on circulating plasma metabolites in 'cafeteria-fed' rats.

1. The effects of 'cafeteria feeding' on primiparous Wistar rats during lactation have been studied by measuring circulating levels of glucose, amino acids, lactate, urea and ammonia as well as glycogen levels in liver and muscle. 2. No significant changes in glucose levels were observed despite alterations in blood glucose compartmentation. 3. Compared with controls, the dams given the cafeteria diet had higher liver glycogen stores which were more easily mobilized at the peak of lactation. 4. Rats given the cafeteria diet showed a lower amino acid utilization than controls and adequately maintained circulating levels, as determined by the lower circulating levels of ammonia and urea. 5. No significant differences in body-weight were observed in the period studied despite increasing dam weight after weaning in the cafeteria-fed group. 6. The size of pups of cafeteria-fed dams was greater than that of controls, and the differences were marked after weaning, when the metabolic machinery of the cafeteria pup maintained high protein accretion and body build-up using fat as the main energy substrate characteristic of the preweaning stage. The controls, however, changed to greater utilization of amino acids as an energy substrate and adapted to high-protein (low-biological-quality) diets with a significantly different pattern of circulating nitrogen distribution.

Amino Acids↗