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At least 865 records · Page 48Linked to original sources
PubMed1991

Short term starvation-induced changes in the kinetic parameters of rat red cell L-alanine and glycine uptake.

Na(+)-dependent L-Alanine and Glycine uptake by rat red blood cells were best fit to a common model of two transport components, saturable transport and diffusion. 24 hours of food deprivation provoked statistically significant increases of the Km and Vmax red cells L-Alanine uptake, whereas the diffusion constant did not change in response to starvation. The Glycine uptake kinetics poorly follows the L-Alanine pattern and no significant response to starvation can be outlined. The physiological meaning of these adaptations has to be related to short term food deprivation regulation, independent of protein synthesis in the erythrocytes. Such mechanisms could be important to account for the previously described changes in the distribution patterns of amino acids between the blood plasma and blood cell compartments in response to short term starvation.

Alanine↗
PubMedDate not supplied

[Age-specific characteristics of the effect of various hormones on the lipolysis in the adipose tissue of rats under normal conditions and in starvation].

Experiments were conducted in vitro; a study was mode of the age peculiarities attending be invluence of adrenaline, ACTH, STH on the lypolysis in the adipose tissue of rats under normal conditions and in starvation. During the process of ageing there occurs no change in the adipose tissue sensitivity to the action of hormones stimulating the lipolysis, but the capacity to react to high hormone doses is decreased. Elevation of the basal lypolysis in the adipose tissue of young rats occurs during starvation; the lypolytic action of the hormones falls. Starvation fails to alter the basal lypolysis in the adipose tissue to react to the hormone action.

Adipose Tissue↗
PubMed1991

Decreased hepatic glycogen content and accelerated response to starvation in rats with carbon tetrachloride-induced cirrhosis.

Glucose homeostasis and fatty acid metabolism are abnormal in patients with cirrhosis. To assess the metabolic response to starvation in an animal model of cirrhosis, glycogen and fuel metabolism were characterized in rats with CCl4-induced cirrhosis studied 2 wk after 10 weekly doses of CCl4. Plasma concentrations of glucose and beta-hydroxybutyrate were not different between fed CCl4-treated and control rats, but plasma nonesterified fatty acid concentrations were higher in cirrhotic animals (0.25 +/- 0.01 vs. 0.39 +/- 0.04 mmol/L; p less than 0.05). After 12 hr of starvation, the plasma nonesterified fatty acid concentration had reached 0.58 +/- 0.04 mmol/L in CCl4-treated rats, compared with 0.38 +/- 0.04 mmol/L in control rats (p less than 0.05). The redistribution of the hepatic carnitine pool toward acylcarnitines, which is characteristic of starvation, was complete after fasting for 12 hr in the CCl4-treated rats, compared with the 24 hr required in control rats. In fed cirrhotic rats, liver glycogen content per gram liver was decreased by 64% compared with control rats (30.0 +/- 5.1 vs. 10.8 +/- 1.1 mg/gm liver wet wt; p less than 0.05). After 12-hr fasting, hepatic glycogen content had fallen to 14.3 +/- 3.9 and 4.8 +/- 0.4 mg/gm liver wet wt (p less than 0.05) in control and cirrhotic animals, respectively. To further characterize the status of glycogen metabolism in cirrhotic livers, activities of glycogen synthase and glycogen phosphorylase were determined. Hepatic active and total glycogen phosphorylase activities normalized to hepatocellular content were unaffected by CCl4 treatment, whereas total glycogen synthase activity was increased by 45%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

Effect of starvation, alloxan diabetes and adrenalectomy on Na+ K+-ATPase of the mucosa of the small intestine of rat.

The dietary stress conditions such as starvation influenced Na+K+-ATPase activity which increased steadily above normal fed levels between the starvation periods of 24--48 hr. Also, an increased enzyme level was observed in alloxan diabetic rats and administration of insulin to diabetic rats led to a tendency towards a lowering of Na+K+-ATPase. Adrenalectomy brought about a lowering of Na+K+-ATPase activity from those of normals while the administration of hydrocortisone induced an enhancement. The results indicate that both starvation and diabetic conditions might cause a stress-like activation of adrenal cortex resulting in increased levels of glucocorticoids which in turn activate the intestinal Na+K+-ATPase activity.

Animals↗
PubMed1989

[Ultrastructural mechanisms of myocardial atrophy in white rats during starvation].

By means of complex morphological, morphometrical and stereological analyses the myocardium of Wistar rats was studied in full alimentary starvation during 6 days. The availability of two mechanisms of myocardial atrophy in adaptation to full starvation was revealed, these are the diminution of dimensions of parenchymatous elements and the decrease of muscle cell number. By ultrastructural investigation of cardiomyocytes the signs of structural protein synthesis decline were revealed, this is a simple myocardial atrophy. In quantitative analysis of cardiomyocytes the decrease of their number without changes in proportions of cells with different nuclei number was observed, that indicated systematic character of muscle cell elimination out of myocardium by apoptosis mechanism involvement, this is a numerical myocardial atrophy. Stereological analysis of myocardial atrophy development in conditions of full starvation determined the main regulated indices, these are the absolute total myofibril mass and mitochondrial mass and surface area.

Animals↗
PubMed1987

Effect of 24-hour starvation on amino acid pool composition and enzyme activities of rat brown adipose tissue.

The effect of 24-hr starvation on the amino acid pool composition and its concentration ratios with respect to blood and plasma as well as the activities of alanine, aspartate and branched chain amino acid transaminases, glutamate dehydrogenase, glutamine synthetase and adenylate deaminase have been studied in rat brown adipose tissue. Starvation induced a considerable decrease of pool amino acid concentration. Alanine and taurine were the amino acids in which the decrease was more marked. Small changes were observed in the activities of the enzymes studied, with decreases only in glutamate dehydrogenase and adenylate deaminase. These changes agree with a decrease in amino acid utilization in this tissue induced by starvation.

AMP Deaminase↗
PubMed1987

Effect of starvation on biochemical indices of renal function in the rat.

The effect of starvation on urinary output and biochemical indices of renal function was investigated in rats. Starvation resulted in a marked fall in water intake. Urinary output paradoxically increased during the first day following starvation, but fell dramatically thereafter. Urinary creatinine excretion and creatinine clearance fell markedly, but plasma creatinine concentration did not alter. Plasma urea concentration and urinary urea excretion fell. Plasma sodium concentration increased, whilst plasma potassium concentration did not alter; urinary sodium and potassium excretion fell. Plasma bicarbonate concentration fell marginally, but the anion gap increased to a greater extent. Following re-feeding, water intake and urine output increased, as did urinary creatinine excretion and creatinine clearance. Plasma urea and urinary urea concentrations, as well as sodium and potassium excretion, increased. Plasma bicarbonate increased and the anion gap decreased. These indices improved within 2 days of re-feeding and were restored to normal in 5 days.

Animals↗
PubMed1987

Effects of starvation and a high-energy diet on rat blood compartmentation of injected radioactive alanine and glucose.

The effects of starvation upon blood compartmentation and differential handling of glucose and alanine have been studied in control and cafeteria-fed rats. The injection of radioactive glucose resulted in higher specific radioactivities in intracellular glucose but lower intracellular amino acid specific radioactivities when compared with the plasma values. The cells/plasma specific radioactivity ratios increased dramatically in cafeteria rats with starvation. The injection of radioactive alanine resulted in higher cell than plasma glucose specific activities, and lower cell amino acid specific activities. All these parameters increased after a 24-hours starvation period. It is concluded that glucose synthetised by the liver is released mainly into the blood intracellular pool, being later liberated into the plasma or directly into the tissues.

Alanine↗
PubMedDate not supplied

[Effect of starvation on the intensity of proteolysis and amidation of proteins in tissues of rats of different ages].

Rates of autolysis and degree of amidation of tissue proteins were studied in rats under conditions of ageing and after starvation during 7 days. Proteins with decreased content of amide groups accumulated in brain, liver tissues and skeletal muscles. This phenomenon occurred apparently due to decrease in the rate of protein autolysis observed in ageing. In testes, where the rate of protein autolysis was similar both in young and old animals, the protein amidation was not altered on the course of ageing. Under conditions of severe starvation activation of proteolysis was observed in cells. At the same time, the amide content was restored in liver and muscle proteins of old rats up to the level, estimated in tissues of young animals. These data suggest stimulation of selective degradation of the deamidated proteins. The activation of autolysis and normalization of the protein amide groups content were not observed in brain of old animals under conditions of starvation.

Aging↗
PubMed1986

Effect of short term starvation on disposition kinetics of chloramphenicol in goats.

The effect of short term starvation on the disposition kinetics of chloramphenicol was determined in goats. The same dosage level (10 mg kg-1) administered intravenously produced higher serum concentrations in the animals when they were starved than when they were not starved. This could be attributed to the significantly smaller (P less than 0.05) volume of the central compartment. Starvation significantly decreased the rate of elimination of chloramphenicol while the apparent volume of distribution of the drug was not altered. A significant decrease in the body clearance, 1.36 +/- 0.95 ml (min kg)-1 in the starved condition compared with 3.78 +/- 2.19 mg (min kg)-1 in the controls, caused a corresponding increase in the half life of chloramphenicol. The decreased rate of elimination was attributed to decreased hepatic microsomal metabolism since starvation did not change the fraction of the dose excreted unchanged in the urine. The clinical significance of the altered disposition of chloramphenicol is that administration at the usual dosing rate would lead to accumulation of the drug and eventual toxicity.

Animals↗
PubMed1986

Comparison between starvation and consumption of a high protein diet in rats: hepatic metabolites and amino acid levels during the first 24 hours.

Changes in hepatic levels of lactate, pyruvate, phosphoenolpyruvate, alpha-ketoglutarate, malate, oxaloacetate, adenine nucleotides, inorganic phosphate, ketone bodies, alanine, serine, glycine, aspartate, glutamate, valine and urea were examined in adult rats during the first 24 h of either starvation or consumption of a high protein (HP) diet. No differences were found between these two conditions in the concentration of metabolites studied or the cytosolic redox state. Under both conditions, the cytosolic phosphorylation state decreased to a low 15 h into the experiment but the changes were more pronounced on the HP diet. Hepatic ketone bodies rose sharply after 12 h, with the increase 2.5 times greater for starved rats. In starvation, hepatic aspartate, valine, and urea were low and glycine was high, whereas the opposite was seen for the HP diet. In both groups, alanine fell within 9 h and remained low thereafter. These findings suggest that, in the first 24 h of starvation, the energy necessary for gluconeogenesis is obtained from fatty acid oxidation, while during HP feeding the energy for both gluconeogenesis and ureagenesis are derived from fatty acid oxidation and amino acid oxidation.

Adenine Nucleotides↗
PubMed1985

Lysosomal enzyme activities in muscle following starvation and refeeding in the saithe Pollachius virens L.

Saithe (Pollachius virens L.) were starved for 66 days at 10 degrees C and activities of aryl sulfatase, acid proteinase, beta-glucuronidase, RNAase and acid phosphatase measured in homogenates prepared from fast and slow myotomal muscles. In fed fish, hydrolase activities were generally higher in slow than fast muscles. With the exception of acid proteinase activity in slow muscle, the activities of all the lysosomal enzymes increased by 70 to 100% during starvation. In general, there was a proportionally larger increase in the hydrolase activities in fast than in slow muscle. In a second experiment, fish were starved for 74 days, and refed for up to 52 days. The increases in aryl sulfatase and acid proteinase activity produced in fast muscle with starvation were found to be rapidly reversed by refeeding. Lysosomal enzyme activities in fish sampled after 10 days refeeding were not significantly different from fed controls. Membrane fractions enriched in aryl sulfatase activity were prepared from the fast muscle of 66-day starved fish. These were capable of degrading both myosin heavy chains and actin to lower molecular weight peptides at acid (pH 5.0), but not at neutral pH. The results suggest a role for lysosomal enzymes in the breakdown of myofibrillar proteins during starvation.

Animals↗
PubMedDate not supplied

Effect of different dietary carbohydrates on some hepatic dehydrogenases and total lipid during starvation and refeeding regimen.

Lipogenic capacity of various dietary carbohydrates starch, glucose sucrose and lactose was tested during ad lib feeding and starvation followed by refeeding. Sucrose was found to have maximal effect on hepatic total lipid and the enzymes in the study followed by glucose and sago while lactose was found to be toxic. Starvation resulted depression in the activities of various enzymes. The enzyme activity inducing effect was again exhibited by sucrose diet during ad lib and restricted refeeding followed by starvation.

Animals↗
PubMedDate not supplied

Acetylcholinesterase activity of rat brain and heart in starvation and protein restriction.

AChE activity was determined in the brain and heart of normal, acute totally starved, chronically semi-starved and chronically protein restricted groups of adult male rats. Neither acute total starvation nor chronic semi-starvation produced significant changes in AChE activity and protein content of the brain, while AChE activity and protein content in the heart were significantly decreased (P less than 0.01) after semi-starvation. Protein restriction, however, produced a significant decrease in AChE activity and protein content of both brain (P less than 0.01) and heart (P less than 0.001).

Acetylcholinesterase↗
PubMed1979

[Effects of starvation on incorporation of glycine in organs of Philosamia cynthia walkeri].

The influence of starvation on protein synthesis in organs from growing Philosamia larvae has been determined. In the fat body, a rapid and continuous decrease in synthesis begins at the onset of starvation. A decrease also occurs in the carcass, but of lesser extent. In the intestine and silkgland, the synthesis increases significantly during the first 12 hours and decreases thereafter. In all organs, the acid soluble glycine pools are drastically modified by starvation for 48 hours: this amino-acid accumulates in the silkglands, remains at a rather stable level in the intestine but decreases in the fat body and carcass. No adjustement of these pools is found at the level of haemolymph acid soluble glycine which increases during the 48 hours. These results are discussed in the context of regulatory mechanisms on metabolic level during feeding or food deprivation periods.

Adipose Tissue↗
PubMedDate not supplied

Content of mitochondrial protein in the planarian Polycelis nigra during starvation and feeding.

To discover the possible mechanisms determining the level of energy metabolism during changes in the body size of animals, the content of mitochondrial protein was studied in planarians during starvation and feeding. In the course of starvation, the relative content of mitochondrial protein decreases, whereas during feeding it increases. Comparison of the experimental results with previous observations on respiration of planarians under similar conditions shows that changes in the level of respiration during starvation and feeding correlate with the content of mitochondrial protein. However, the degree of the functional load on the mitochondria must be taken into account under these circumstances.

Animals↗
PubMed1984

Effect of maternal starvation on fetal tissue nucleic acid, plasma amino acid and growth hormone concentration in sheep.

The measurement of nucleic acids in fetal tissues as well as plasma growth hormone and amino acids was used in conjunction with fractional protein synthetic rates to investigate the mechanism of reduced fetal protein synthesis following acute maternal starvation. The nucleic acid analysis of fetal tissues from fed and 48 h starved ewes (120-130 days gestation) demonstrated a significant reduction in kidney RNA and heart DNA concentration in the starved fetuses. The RNA synthetic capacity (RNA/protein) was also seen to decrease in the starved fetuses both for liver and kidney tissue as was the protein/DNA in the lung tissue. Most revealing, however, were the measurements of RNA and DNA activity or the extent to which the protein synthesizing capacity was realized (g protein/g RNA or DNA/day). Significant reductions were observed in liver and brain RNA activity as well as the DNA activity of liver, lung, kidney and muscle. Plasma aminograms demonstrated reductions in maternal histidine, methionine and isoleucine as well as reductions in fetal glutamate and phenylalanine following starvation. Conversely, the fetal growth hormone levels were seen to rise under the influence of maternal starvation. The impact of maternal nutrient deprivation during gestation on fetal metabolism appears to depend on the ontogenic stage of development of specific tissues at the time the deprivation occurs.

Amino Acids↗
PubMed1984

Effect of starvation on degradation of rat liver nuclear proteins.

Starvation is characterized by rapid loss in liver weight and proteins. The loss in liver protein is reflected in loss of protein in most organelles including mitochondria, microsomes, and cytosol, with the exception of nuclei. The nuclear proteins increase per unit weight of liver during starvation and this holds true for both histone and non-histone fractions. Comparison of degradation pattern of histone and non-histone fractions with microsomal fraction indicates a significantly different profile. The nuclear proteins reflect a pattern of decreased degradation during starvation. The increase in the activity of lysosomal enzyme cathepsin D measured during this period was indicative of general increase in catabolic processes. However, the nuclear protease activity decreased during this period, suggesting an organelle compartmentation of degradation process.

Animals↗