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PubMed1976

The role of potassium in the control of ammonium excretion during starvation.

Administration of KC1 0.5 mmol/kg/day to subjects undergoin prolonged starvation reduced daily urinary ammonium and beta-hydroxybutyrate excretion by one-third. These changes were accompanied by an improvement in potassium balance and an increased rate of chloride excretion. A similar fall in ammonium excretion occurred in a second group of subjects after administration of KHCO3 0.5 mmol/kg/day. Ketone body and bicarbonate excretion remained unchanged in this group while potassium balance improved. In both the first and second groups urine pH fell significantly as the rate of excretion of urinary buffer (ammonium) decreased. When the dose of KHCO3 was increased to 1.5-2.0 mmol/kg/day in fasting subjects, the urine was alkalinized, and ammonium excretion fell to negligible levels, resulting in nitrogen sparing of 2.0 g/day. The results indicate that one-half of the increase in ammonium excretion observed in starvation is due to potassium deficiency. Nitrogen wastage caused by losses of urinary ammonium during starvation can be virtually eliminated by potassium supplementation and urinary alkalinization. The decrease in beta-hydroxybutyrate excretion after potassium chloride administration was not caused by a fall in the rate of nonionic diffusion of this organic acid related to the reduction in urine pH. The reason for the fall in beta-hydroxybutyrate excretion is not apparent, though it was associated with an increase in chloride excretion.

Acid-Base Equilibrium↗

PubMed1979

Maternal serum metabolites during prolonged starvation in pregnant pigs.

Pregnancies in pigs were sustained during periods of prolonged starvation in spite of maternal body weight losses exceeding 40 kg. Maternal stores of protein were made available for feto-placental development during starvation of the dam. Concentrations of maternal serum proteins, urea nitrogen, electrolytes, and iron were determined in sequential blood samples of healthy Yorkshire pigs during a prolonged period of 40 days inanition (water only) in either the middle third (days 30-70) or last third (days 70-110). Serum protein levels remained similar to full-diet controls throughout these two periods, whereas serum concentrations of albumin and urea N increased primarily during the last third of gestation in starved dams. Serum Na+ levels declined during prolonged inanition while Ca2+ increased and K+ remained unchanged. It was only near term that Fe2+ levels decreased in those dams starved during a period of 40 days in the last third of pregnancy. These results indicated that maternal serum components were sustained at adequate levels to maintain normal development of conceptuses during prolonged starvation in either the middle third or last third of pregnancy in the pig.

Animals↗

PubMed1981

The antilipolytic effect of insulin in human adipose tissue in obesity, diabetes mellitus, hyperinsulinemia, and starvation.

The antilipolytic effect of insulin in vitro was investigated in conditions known to be associated with resistance to the effect of insulin on glucose metabolism. Human subcutaneous adipose tissue was obtained from 14 obese subjects before and during starvation for 7 days, 12 untreated non-insulin dependent diabetics (NIDDM), 6 untreated insulin dependent diabetics (IDDM), and 10 nonobese control subjects. The tissue was incubated with and without insulin in concentration ranging from 1-10,000 microunits/ml. Responsiveness (maximum effect) and sensitivity to insulin were determined under basal induction conditions, since insulin had a bimodal effect on noradrenaline stimulated lipolysis. Under normal conditions both insulin sensitivity and insulin responsiveness were positively correlated with the basal rate of lipolysis. In obesity, IDDM and NIDDM there were no change in insulin sensitivity or in insulin responsiveness. When the obese subjects were divided into one hyperinsulinemic group (6 individuals) and one group with normal fasting serum insulin levels (7 individuals) a similar antilipolytic effect of insulin was observed in the two groups. During starvation there was a 20-fold increase in insulin sensitivity (p less than 0.01) but no change in insulin responsiveness in femoral fat and only a decrease in responsiveness (p less than 0.01) in abdominal fat. The present data supports the view that antilipolysis in human fat cells is not involved in the insulin resistance seen in obesity, starvation, diabetes and hyperinsulinemia.

Adipose Tissue↗

PubMed1985

Size distribution of ribosomes in biopsy specimens of human skeletal muscle during starvation.

The changes in the poly- and monoribosome distribution and in the total ribosome concentration in muscle during short term starvation were investigated. Transcutaneous muscle biopsies of 50 mg wet wt were taken from healthy human subjects, nonstarved and after one, two, and three days of total starvation. The percentage amount of polyribosomes was significantly lower (P less than 0.02) on days 2 and 3 of starvation than on day 0 (nonstarved). No significant sex-dependent differences were observed between the group of five females and six males. Ribosome concentration per g wet wt of muscle tissue was significantly lower on day 3 than on each preceding day (P less than 0.05). The reproducibility of the polyribosome analyses, together with the changes observed, suggest a future application of this method for evaluation of the effects of nutritional support in patients with posttraumatic and septic conditions.

Acetoacetates↗

PubMed1985

Orotic acid excretion during starvation and refeeding in normal men.

The effects of acute food deprivation and subsequent refeeding on urinary orotic acid excretion were examined in nine healthy adult male subjects. During inpatient metabolic ward conditions, the volunteers were fed a nutritionally complete, pyrimidine- and purine-free diet for three days and subsequently underwent a ten-day fast followed by a ten-day period of refeeding by total parenteral nutrition. Mean daily excretion of 4.33 +/- 0.23 mg (2.77 +/- 0.12 mg/g creatinine) of orotic acid during the enterally fed state was significantly reduced (mean 46 +/- 5%) in all subjects during starvation. This reduction in the excretion of orotic acid during starvation is more likely related to a lowered rate of production and utilization. The starvation adaptation of orotate excretion occurred more rapidly than did the decrease in urinary nitrogen loss. All subjects showed an increase (mean 48 +/- 14%) in the excretion of orotic acid during the first day of refeeding which continued throughout the refeeding phase. A significant positive correlation was shown between the daily orotic acid excretion and nitrogen intake (r = 0.98) or protein balance (r = 0.83). The response to refeeding of acutely malnourished normal male is an increase in orotic acid excretion with a decrease in whole body protein catabolism.

Adult↗

PubMed1986

Polyribosome concentration in human skeletal muscle after starvation and parenteral or enteral refeeding.

Posttraumatic and septic states cause a loss of body proteins resulting in a negative nitrogen balance. The major part of the excreted nitrogen is derived from the proteins of skeletal muscle. The loss in proteins is due to a decrease in protein synthesis rather than an increase in protein degradation. Nutritional support may increase protein synthesis, and determination of its activity in skeletal muscle will give information on the utilization of nutrients in catabolic patients. The effect of nutritional support on healthy subjects was studied to achieve a background for future clinical studies. Male volunteers between 20 and 40 years old were refed parenterally or enterally after three days of starvation. Muscle biopsies (50 mg) were analyzed for the size distribution of ribosomes in a sucrose density gradient, and the ribosome concentration was determined per mg of DNA. Changes in the percentage content of polyribosomes preceded those of the total ribosome concentration. The total polyribosome concentration per gram wet weight of skeletal muscle decreased significantly during starvation. After one and two days of refeeding, a significant increase was observed, but the original level of the nonstarved subjects was not reached. The total ribosome concentration increased upon refeeding, but was not significantly different from that of the starved condition. The nitrogen balance was negative during starvation but attained equilibrium after two days of refeeding. Nutrition administered by the parenteral or enteral route were equally effective in restoring protein synthesis.

3-Hydroxybutyric Acid↗

PubMed1988

In vivo glucose utilization in rat tissues during the three phases of starvation.

Three phases of starvation have been described from changes in protein and lipid utilization in birds and mammals. In the present study, tissue glucose utilization was measured in vivo during these three phases, using a 2-deoxy-[1-3H]glucose technique in the anesthetized rat. According to this technique, the term glucose utilization therefore refers to transport and phosphorylation of glucose in tissues, ie, whatever is the fate of glucose. Whole-body glucose turnover rate, which was determined by a continuous infusion of [3-3H]glucose, decreased by 40% during the first two days of starvation (phase 1); it did not change thereafter, neither in the protein-sparing phase 2 nor in phase 3, which is marked by an increase in net protein breakdown. Two days of starvation caused a marked decrease in the glucose utilization in skeletal muscles; this decrease was higher in oxidative muscles (65% in diaphragm, 66% in soleus) than in glycolytic muscles (31% in extensor digitorum longus, 34% in epitrochlearis). Glucose utilization also decreased in heart atria (75%), heart ventricles (93%), and white adipose tissue (54%); by contrast, there was a two-fold increase in glucose utilization in brown adipose tissue and no change in brain and skin. No variations were observed in glucose utilization in any of the tissues from phase 1 to phase 2. However, phase 3 was marked by a decrease in glucose utilization in extensor digitorum longus (45%), brown adipose tissue (76%), brain (29%), and skin (40%), whereas there was a 2.3- and 3.4-fold increase in glucose utilization in diaphragm and heart ventricles, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1992

Effect of starvation or restriction on self-selection of macronutrients in rats.

Two models of food deprivation were used to study feeding behavior: starvation and dietary restriction. Rats starved for 3 days had decreased protein intake during the first 2 days of refeeding followed by increased carbohydrate consumption compared to controls. During refeeding, total intake was initially low compared to controls. In a second starvation study of similar design, brain tissues [raphe, ventromedial hypothalamus (VMH)] and sera were collected for analysis before refeeding and on day 2 of refeeding. Starved and starved-refed rats had increased serum beta-hydroxybutyrate versus controls. In rats restricted for 5 days (5 g/day), total food intake was increased immediately and was characterized primarily by carbohydrate intake. Serotonin levels in the raphe were decreased in restricted rats and 5-hydroxyindole acetic acid (5-HIAA) increased in restricted-refed rats. Restriction caused an increase in blood levels of beta-hydroxybutyrate and a decrease in insulin and glucose compared to controls. Fat selection remained low throughout all studies. The data suggest that starvation and food restriction elicit different patterns of macronutrient selection upon refeeding.

3-Hydroxybutyric Acid↗

PubMed1987

Effect of diet and starvation on the activity state of branched-chain 2-oxo-acid dehydrogenase complex in rat liver and heart.

In rats fed a high-protein diet, the branched-chain 2-oxo-acid dehydrogenase complex in liver was essentially fully active and its activity state was unaffected by subsequent starvation for 48 h. Feeding with a low-protein diet led to a decrease in the activity state which was essentially reversed by 48 h of starvation. In heart, the enzyme was primarily inactive (activity state 18%) in rats fed a high-protein diet, with both low-protein diet and starvation leading to a further decrease in the activity state.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMed1986

Concentrations of carbohydrates and lipids of guinea pigs after five days starvation.

The concentrations of serum total lipids, cholesterol and triglycerides of guinea pigs were determined under normal conditions and after 5 days fasting. Serum glucose and liver glycogen levels were also estimated under both conditions. The amounts of serum total lipids and cholesterol were significantly increased as a result of starvation, whereas, fasting had no significant effect on serum triglycerides. Liver glycogen was rapidly decreased in response to starvation in a highly significant manner. However, starvation did not affect serum glucose of guinea pigs.

Animals↗

PubMed1976

Induction of rat liver phosphoenolpyruvate carbonxykinase (GTP) by cyclic AMP during starvation. The permissive action of glucocorticoids.

The effect of starvation on the activity of hepatic phosphoenolpyruvate carboxykinase (GTP:oxaloacetate carboxy-lyase (transphosphorylating), EC 4.1.1.32), and on the response of the enzyme to N6-O2'dibutyryl adenosine 3', 5'-monophosphate was investigated in intact and glucocorticoid-deprived rats. In the liver of intact animals, starvation produced a rapid increase in the concentration of cyclic AMP and a corresponding increase in the activity of phosphoenolpyruvate carboxykinase. The kinetics of both changes were not affected by adrenalectomy. Injection of N6-O2'-dibutyryl adenosine 3', 5'-monophosphate into intact starved rats resulted in an immediate, dramatic increase in phosphoenolpyruvate carboxykinase activity above the starvation level. Adrenalectomy completely blocked the response of the enzyme to the cyclic nucleotide. Restoration of hydrocortisone to the adrenalectomized animals restored the full N6-I2'dibutyryl adenosine 3', 5'-monophosphate effect after a lag period of 2 h. The physiological significance of these findings is considered. The data are interpreted with regard to the current hypothesis that glucocorticoids promote an increase in translatable phosphoenolpyruvate carboxykinase mRNA, while cyclic AMP enhances the translation of preexisting specific mRNA templates.

Adrenalectomy↗

PubMed1979

Changes in lung lysyl oxidase activity in streptozotocin-diabetes and in starvation.

The effects of streptozotocin-induced diabetes and of starvation on the lysyl oxidase activity of rat lung were investigated. Enzyme activity was elevated 2--3 fold in the lungs of streptozotocin-diabetic rats. In contrast, starvation of rats produced a rapid loss of lung lysyl oxidase activity, with levels approximating 25% of control values after 48--72 h of starvation. Enzyme activity was essentially fully restored to control values upon refeeding the 48-h starved animals for 3 h. These studies demonstrate the responsiveness of lysyl oxidase to these physiological states and suggest a component, enzymatic basis of change in lung function known to occur in the diabetic state.

Amino Acid Oxidoreductases↗

PubMed1982

Evolution of gluconeogenic enzyme activities during starvation in liver and kidney of the rainbow trout (Salmo gairdneri).

1. There was a general increase in the activities of enzymes involved in gluconeogenesis in liver and kidney of rainbow trout, Salmo gairdneri, during the second month of starvation. 2. The need of gluconeogenesis during the first month of the starvation period was probably minimal because of the utilization of liver glycogen as a source of blood glucose. 3. The decline of fat was more pronounced than that of protein total content in absolute values, suggesting that lipid reserved were the main sources of energy during starvation.

Animals↗

PubMed1989

Long-term starvation in Xenopus laevis Daudin--III. Effects on enzymes in several tissues.

1. Adult, female Xenopus laevis were subjected to 12 months of starvation. 2. Starvation resulted in a continuous reduction in the activity of both hepatic and renal glucose-6-phosphate dehydrogenase. 3. Fructose-1,6-diphosphatase was significantly reduced at months 10 and 12 in the liver, and at months 4, 10, and 12 in the kidney. 4. Pyruvate kinase activity of muscle and liver decreased during the experimental period whereas the renal enzyme remained essentially unchanged. 5. Both hepatic and renal glutamate-pyruvate transaminase (GPT) and hepatic glutamate-oxaloacetate transaminase (GOT) showed a reduction of activity after 2 and 4 months of starvation followed by an increase in GPT but not in GOT.

Alanine Transaminase↗

PubMed1989

Effects of clofibrate treatment and of starvation on peroxisomes, mitochondria, and lipid droplets in mouse hepatocytes: a morphometric study.

Adult male mice of the NMRI strain were treated with a diet containing 0.5% clofibrate for 4 days to study its effects on peroxisomes, mitochondria, and lipid droplets in hepatocytes. Animals were also starved overnight to study the additional effects of starvation. Starvation of control animals had small effects on peroxisomes while the mitochondria became enlarged and occupied more of the cytoplasm. The number and fractional area of lipid droplets increased fivefold. Clofibrate treatment caused a doubling in number and average size of peroxisomes. No significant effects were observed in the number of mitochondrial profiles or lipid droplets although the size of the latter decreased to a third the value of the fed control. Starvation of clofibrate-treated animals led to a slight increase in the number of peroxisomes although their average size decreased by 30%. Mitochondrial average area increased and their fractional cytoplasmic area increased despite the decrease in numerical density. The number of lipid droplets increased twofold compared to that of clofibrate-treated animals while the size was not affected.

Animals↗

PubMed2003

Severe acidosis caused by starvation and stress.

A 1-year-old boy had severe anoxic brain injury owing to a cardiorespiratory arrest. He had an initial metabolic acidosis, but this largely resolved by hospital day 2. He then had a persistent, profound metabolic acidosis. Evaluation on hospital day 6 found that the patient had ketonemia, ketonuria, and a normal serum glucose level; he had received no intravenous dextrose during his hospitalization. The dextrose-free fluids were given initially to protect his brain from the deleterious effects of hyperglycemia after brain injury. Continuation beyond 24 hours was inadvertent. The initiation of dextrose-containing intravenous fluids produced a rapid resolution of his metabolic acidosis. Starvation usually produces a mild metabolic acidosis, but when combined with physiologic stress, starvation may cause a severe metabolic acidosis. Among the few reports of severe starvation ketoacidosis, our case is unique because the patient was monitored closely in an intensive care unit, allowing us to describe the time course of the acidosis in detail.

Fatal Outcome↗

PubMed2005

Erythrocyte senescence and haematological changes induced by starvation in the neotropical fish traíra, Hoplias malabaricus (Characiformes, Erythrinidae).

Adult specimens of traira (Hoplias malabaricus Bloch) were subjected to long-term starvation (30 to 240 days) and re-fed for 30 days after 90 and 240 days of food deprivation. Counting of immature erythrocytes in peripheral blood showed that erythropoiesis decreased significantly during the first 30 days of food deprivation. The results suggest that a process of senescence takes place in the pre-existent red blood cells and that the cells are not replaced during starvation. After 240 days of starvation, H. malabaricus had a significantly reduced number of red blood cells, causing changes in hematocrit and blood indices (mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration). Furthermore, during this period, the fish presented leukopenia (lymphocytopenia) and thrombocytopenia. After re-feeding, the number of leukocytes and thrombocytes recovered, but the red blood cell number remained reduced and there was a significant increase in abnormal red cell nuclei.

Animal Feed↗

PubMed2005

Energy metabolism and nutrient oxidation in young pigs and rats during feeding, starvation and re-feeding.

The investigation included individual measurements of energy metabolism and oxidation of nutrients in 12 castrated male pigs (Sus scrofa) (20-40 kg) and 12 male rats (Rattus norvegicus) (65-105 g). Measurements were carried out in 5-6 days balance periods with ad libitum feeding, followed by 3-4 days of starvation and 4 days of re-feeding. O2 consumption and CO2 production were measured by open-air-circuit respiration units. In the feeding period, protein retention in relation to metabolic live mass (kg(0.75)) was identical for pigs and rats, while there was a tendency of a higher fat retention in pigs than in rats. A substantial part of digested carbohydrate was not oxidized, but transferred to fat metabolism without significant differences (P > 0.05) between pigs and rats (18% vs. 22%). During starvation, nitrogen excretion in urine decreased to 226 mg/kg(0.75) in pigs and to 429 mg/kg(0.75) in rats, indicating a lower rate of body protein degradation in pigs. Heat production was reduced to 592 and 338 kJ/kg(0.75), while the contribution of heat from oxidation of protein (OXP), carbohydrate (OXCHO) and fat (OXF) showed the same pattern for pigs and rats during all periods. Heat production during feeding and re-feeding was covered by OXP+OXCHO with no OXF and reversibly after 2 days of starvation by OXP+OXF with no OXCHO. The rat may be a suitable model for pigs regarding general patterns of quantitative nutrient partition, but any direct application of results measured with rats to pigs shall be taken cautiously, keeping in mind that modern pigs have been selected for a high growth rate and protein deposition which has not been the case for the laboratory rat.

Animal Feed↗