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X Remesar

Publications and source records attributed to X Remesar.

At least 163 records · Page 9Linked to original sources
PubMed1983

Adenylate deaminase activity in the tissues of the rat during its breeding cycle.

The adenylate deaminase activity of muscle, liver, kidney, brain, intestine, stomach and adipose tissue have been measured during pregnancy, lactation and post-lactation of the rat. No significant changes have been found in muscle and kidney, with depressed values in the liver of pregnant rats--in agreement with the loss of metabolic rôle in nitrogen handling during this period--. Adipose tissue changes as well as those of skin actually followed anatomical changes in fat content of both tissues. Stomach and intestine patterns were significantly different, with a maximum for the bowel at mid-lactation.

AMP Deaminase↗
PubMed1982

Glycogen and glycogen enzymes in the liver and striated muscle of rats under altered thyroid states.

Changes induced in liver and striated muscle glycogen and glycogen enzymes (glycogen synthetase, glycogen phosphorylase and alpha-amylase) by hypothyroidism and hyperthyroidism in rats have been determined. There were no changes in liver glycogen synthetase, phosphorylase and amylase activities in the hypothyroid group. Hyperthyroid rats showed lower liver glycogen synthetase, phosphorylase a and amylase activities. In muscle, hypothyroid rats had lower phosphorylase activity. In the hyperthyroid group glycogen synthetase was increased.--The results presented do not completely agree with the glycogen levels found in both tissues studied, and they are obviously more related to other factors such as glucose availability. It can be concluded that under the conditions studied, the glycogen enzyme levels could not alone explain the variations of glycogen levels.

Amylases↗
PubMed1982

Glutamine synthetase activity in rat tissues during pregnancy and lactation.

The glutamine synthetase activities of liver, striated muscle, kidney, brain, stomach, adipose tissue, small intestine and skin of rats during pregnancy, lactation and post-lactation were investigated as a probe of glutamine--and thus of ammonia--metabolism under a situation of altered amino acid utilization. There were significant increases in muscle activity in mid-pregnancy and in post-lactation. A transient relative decrease was observed in muscle enzyme on day 20 of lactation, compensated by an increase in small intestine activity. The results are discussed in light of the transporting role of nitrogen between peripheral and splanchnic tissues attributed to glutamine, as well as to the detoxyfying role of the enzyme for removal of nitrogen generated by the conceptus and by catabolism of amino acids under the increasing demand for energetic fuels in the peak of lactation.

Animals↗
PubMed1982

Amino-acid enzyme activities in liver and kidney of developing rats.

The amino-acid enzymes (aspartate-, alanine- and tyrosine transaminases, serine dehydratase, glutamate dehydrogenase, glutamine synthetase, adenylate deaminase and arginase) activities in the liver and kidney of developing rats (days 19 and 21 after conception and 1, 5, 10, 20 and 30 after birth) compared with adults were determined in crude homogenates. Most enzymes attained the adult levels early after birth or at weaning, showing a marked trend towards amino-acid nitrogen conservation during late foetal and specially during the neonatal period, increasing their activity during lactation. It is postulated that these changes are closely related to availability of low grade protein in diet as well as to maturation of amino-acid homeostasis maintenance for growth.

AMP Deaminase↗
PubMed1982

Changes induced in rat plasma composition by lactation.

Changes in rat plasma composition in post-partum period were studied from day 1 to post weaning recovery situation (day 40). Urea levels showed a significant increase at the peak of lactation, and glycerol levels showed a decrease towards late lactation. Changes in the plasma aminogram were more marked during the maximal intensity of lactation (days 10-20) and in postlactation. Low trypthophan levels were sustained throughout the lactation period. The combined amino acids showed significant increases on day 10 of lactation, and increases in non-essential and total amino acids in post-lactation (40 days). These results point towards increased amino-acid utilization during lactation.

3-Hydroxybutyric Acid↗
PubMed1981

Glutamine synthetase activity in the organs of fed and 24-hours fasted rats.

Glutamine synthetase activity in several rat tissues had been measured. Liver contains the highest specific activity followed by stomach, brain, kidneys, intestine, skin, adipose tissue and striated muscle - that had the lowest specific activity both with regard to tissue, protein and DNA weight. Per unit of animal weight, liver and muscle contain similar activities, 24 Hours of fasting induced a significant decrease in liver, stomach, intestine and skin glutamine synthetase, compensated by an increase in muscle activity. During fasting, the splanchnic glutamine synthetase activity is lowered and that of peripheral tissues is increased, thus favoring a net glutamine flux from peripheral to splanchnic organs.

Animals↗
PubMed1981

Adenylate deaminase activity in the rat. Effect of 24 hours of fasting.

The adenylate deaminase activity of liver, kidneys, brain, striated muscle, stomach, intestine, skin and adipose tissue of fed and 24 hours fasted rats has been studied. The level of activity of the enzyme in muscle is at least an order of magnitude higher than in other organs. Fasting induced a significant increase in the muscle adenylate deaminase activity, while in kidneys, skin, small intestine, liver and adipose tissue, significant decreases were observed and practically no changes were found in brain and stomach. The possible incidence of these changes upon the overall alpha-amino nitrogen economy of the fasted animals is discussed.

AMP Deaminase↗
PubMed1981

Metabolic effects of short term food deprivation in the rat.

The effects of food deprivation for up to 24 hours on plasma metabolic parameters in the rat have been studied. Liver dry weight and glycogen content dropped significantly from 3 hours of food deprivation onwards. Total muscle glycogen supplied about as much glycosyl residues or precursors as did the liver. Plasma glucose, urea, lactate and total and essential amino acids decreased significantly from 3 hours of fasting onwards. Glycerol, free significantly from 3 hours of fasting onwards. Glycerol, free fatty acids, beta-hydroxybutyrate and acetoacetate showed significant increases with fasting. Alanine, serine, arginine, threonine, aspartate plus asparagine and proline showed significant decreases with fasting. Several other amino acids showed almost no change with fasting. Lysine, leucine plus isoleucine and taurine showed biphasic changes in their concentrations with a minimum at 6 hours and a transient recovery at 12 hours of fasting Essential amino acids decreased more than the non essential ones. With fasting there is a shift in ammonia disposal with lower urea concentrations as nitrogen is better conserved. The results seem to suggest that there is a constant release of substrates, through liver and peripheral tissue proteolysis, that is counteracted by differential utilization of amino acids during fasting.

Amino Acids↗
PubMed1981

Changes in glutamine synthesis activity in the different organs of developing rats.

The changes experienced by the glutamine synthetase activity in the liver, kidney, striated muscle, adipose tissue, brain, stomach, small intestine and skin of developing rats have been estimated. Skin and stomach enzymes attained the adult values in the late foetal period. Striated muscle, intestine and kidney glutamine synthetase belonged to the neonatal cluster, while liver and brain rose to values comparable to those of adults in late suckling. Glutamine synthesis between different organs of the rat during development matures soon after birth, gaining a considerable importance that helps to compensate the lack of availability of other nitrogen transport systems between peripheral and splanchnic bed organs in developing rats.

Adipose Tissue↗
PubMed1981

Effect of short term fasting on plasma composition of lactating rats.

The effects of a 24-h fast upon plasma and blood components of the lactating rat on day 20 after parturition have been determined. Body weight decrease observed with fasting was more marked in nursing dams than in controls. The changes observed agree with a limited use of lipidic resources, exhaustion of liver glycogen and considerable utilization of amino acids as energetic - as well as gluconeogenetic - substrates. Blood and plasma glucose were maintained in fasted dams at a level comparable with that of controls. The actual variations observed in the plasma aminogram were limited, showing a remarkable maintenance of the dam's own amino-acid homeostasis.

Amino Acids↗
PubMed1981

Effect of ether, sodium pentobarbital and chloral hydrate anesthesia on rat plasma metabolite concentrations.

The effect of ethyl ether, pentobarbital sodium (Nembutal) and chloral hydrate anesthesia on the concentrations of glucose, lactate, glycerol, insulin, individual amino acids and urea have been studied in rat plasma, as well as the glycogen content in the animal liver and striated muscle. Control animals were injected with saline solution. Two samples were taken from each animal at 15 and 30 minutes from the beginning of anesthesia. These samples were obtained from the cut tail's tip and from the neck wound produced by beheading the animal. Results show considerable differences between the three sets of animals and their controls as well as in their tail verus neck values. The overall effect of the three anesthetics used were roughly the same in spite of their different actions upon the different parameters studied. This was most marked in the aminograms. Significant changes induced were rather similar in number for all. The metabolite concentration profile in each situation may be used as a reference for possible artifacts induced by any experimental approach using these anesthetics.

Amino Acids↗
PubMed1980

Changes-induced in liver and muscle glycogen and glycogen enzymes by 24-hour fasting in the rat.

Liver and muscle glycogen content, and the activities of glycogen synthetase, glycogen phosphorylase and alpha-amylase have been measured in fed and 24 hours fasted rats. Muscle and liver glycogen account for similar amounts of glycosyl residues liberated in this period of food deprivation. With fasting, liver glycogen synthetase activity decreases somewhat, increasing the I versus total ratio; the liver phosphorylase activity decreases considerably and amylases remain constant. In muscle, total synthetase remains constant with fasting, but the I versus total ratio decreases; phosphorylase activity decreases very considerably and alpha-amylase activity increases to almost thrice the values found in fed animals. These changes reflect a tendency towards conservation of glycogen primers with a preparation to increase glycogen synthesis when glucose would be available. In muscle also, the amylase increase in activity would be tentatively explained as a partial replacement of phosphorylase activity as a means of glucose mobilization from glycogen.

Amylases↗
PubMed1980

Changes in alanine transaminase activity in several organs of the rat induced by a 24-hour fast.

The activity of alanine transaminase in the liver, intestine, stomach, striated muscle, kidneys, adipose tissue, brain and skin of fed and 24-hours fasted adult rats has been determined. The range of activities expressed per unit of protein and DNA weight is rather similar in most organs, with highest values for the liver enzyme. Fasting induced significant increases mainly in peripheral organs, with a combined 35% increase, whereas the liver capability actually decreased by 14% because of the decrease in liver size; and all other splanchnic extrahepatic tissues activity studied increased by 22%. The results obtained agree with the postulated activity of the glucose-alanine cycle under these conditions of fasting.

Alanine Transaminase↗
PubMed1980

Activities of enzymes involved in amino-acid metabolism in developing rat placenta.

Aspartate transaminase, alanine transaminase, glutamate dehydrogenase, arginase, serine dehydratase, tyrosine transaminase, glutamine synthetase, glutaminase and adenylate deaminase activities were measured in crude homogenates of 12, 19 and 21-day rat placentae. There is a considerable quantitative importance in enzymes able to produce free ammonia, such as adenylate deaminase and glutamate dehydrogenase, activity that progressively decrease with the age of placenta. The glutamine synthetase and tyrosine transaminase activities increase with age, while serine dehydratase decreases considerably and aspartate and alanine transaminase do not change practically. Arginase shows a maximum at 19, with lower 12 and 21-day activities. No measurable glutaminase activity has been found. The possible implications of the enzymes studied upon the ammonia-producing activity of rat placenta are discussed together with the relative decreasing role of placenta for the overall metabolic activity of the foetus, especially during the last phases of its development.

AMP Deaminase↗
PubMed1980

Effect of stress and sampling site on metabolite concentration in rat plasma.

The effect of mild stress on various plasma metabolites in the rat has been studied. Mild stress resulted in significant decreases in liver size and glycogen content, as well as in an increase of blood glucose. In addition, plasma lactate, insulin, glycerol and urea, as well as a number of amino acids were altered by stress. These data indicate that minimal stress can have major effects upon the composition of blood, and suggest the need for strict precautions on the handling of animals during blood sampling. The site of blood extraction--tail tip vs. neck--was also found to have a significant effect on plasma lactate, glucose and urea concentrations. In stressed animals the differences between tail- and neck blood composition were increased.

Amino Acids↗