Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Approx. 85% of liver phosphoenolpyruvate carboxykinase is associated with the mitochondrial fraction in the fed guinea pig. Enzyme activity is unchanged in diabetes, but doubles during starvation. In contrast with earlier reports, both cytoplasmic and mitochondrial activities were found to be increased. 2. In kidney cortex, total enzyme activity is increased in both starved and diabetic animals. These changes are associated with increases in the cytoplasmic activity alone. 3. In diabetic animals the mean blood-glucose concentration was 23.1 mM. Other blood metabolites were lower than those in the rat, and the animals did not show significant ketosis. 4. Changes in the rates of gluconeogenesis from lactate and propionate paralleled those in phosphoenolpyruvate carboxykinase activity.
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PMID:The effects of starvation and experimental diabetes on phosphoenol-pyruvate carboxykinase in the guinea pig. 14 29

By means of the microdissection technique applied on kidney tissue, the following results were obtained: Hexokinase, an enzyme of glycolysis, revealed a low activity in the proximal and a high activity in the distal tubule. This distribution pattern is consistent with the finding that glucose is the main fuel for the distal tubule. Glucose-6-phosphatase, an enzyme of gluconeogenesis, demonstrates a significant activity in the distal tubule and in the glomerulus. Both structures are, however, no glucose producers. Phosphoenolpyruvate carboxykinase, the key enzyme of gluconeogenesis, is found only in the segments of the proximal tubule. The distal tubule lacks any activity. This is also the case during starvation and metabolic acidosis when gluconeogenesis is stimulated. Glutamic dehydrogenase, -an enzyme possibly connected with ammoniagenesis-, malate- and lactate dehydrogenase-, enzymes involved with hydrogen transfer through the mitochondrial membrane-, showed a close parallelism to phosphoenolpyruvate carboxykinase in their distribution along the proximal tubule. The bidirectional function of glyceraldehyde-P dehydrogenase is well documented by the close correlation to phosphoenolpyruvate carboxykinase (gluconeogenesis) in the proximal tubule and to pyruvic kinase (glycolysis) in the distal tubule.
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PMID:Metabolic patterns in various structures of the rat nephron. The distribution of enzymes of carbohydrate metabolism. 17 83

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.
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PMID:Induction of rat liver phosphoenolpyruvate carbonxykinase (GTP) by cyclic AMP during starvation. The permissive action of glucocorticoids. 18 Oct 80

The effect of cold exposure (5 degrees C) on the concentration of cyclic AMP and on the activity of phosphoenolpyruvate carboxykinase (GTP: oxaloacetate carboxy-lyase (transphosphorylating), EC 4.1.1.32) was investigated in the liver of intact and adrenalectomized starved rats. Intact starved rats responded to cold exposure with a large increase in both the concentration of hepatic cyclic AMP and the activity of phosphoenolpyruvate carboxykinase above the starvation level. Adrenalectomy did not impair the cold-induced maximum elevation of cyclic AMP but totally prevented the response of the enzyme to cold. Yet, this response was completely restored by hydrocortisone treatment, while the steroid per se had no effect on enzyme activity. In isolated perfused livers of intact starved rats dibutyryl cyclic AMP provoked an immediate dramatic increase in phosphoenolpyruvate carboxykinase activity above the starvation level even if mRNA synthesis was inhibited by cordycepin. However, cyclic AMP was ineffective in increasing enzyme activity in livers of adrenalectomized rats. From these results it is suggested (i) that in starved rats the adaptation to the enhanced glucose demand provoked by cold exposure includes the induction of hepatic phosphoenolpyruvate carboxykinase above the starvation level, (ii) that this induction is due to the cold-induced increase in hepatic cyclic AMP levels, (iii) that cyclic AMP stimulates enzyme synthesis at a post-transcriptional step and (iv) that the cold-induced cyclic AMP-mediated induction of phosphoenolpyruvate carboxykinase above the starvation level requires the "permissive" effect of glucocorticoids.
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PMID:Effect of cold exposure on phosphoenolpyruvate carboxykinase (GTP) activity and cyclic amp concentration in livers of starved rats. Role of glucorticoids. 18 3

1. The development of glycerolkinase before and after birth was investigated in liver and kidney of rat and hamster. In rat liver, enzyme activity increased very slowly before birth and rapidly thereafter, reaching adult values at the 6th day of postnatal life. In hamster liver, glycerolkinase was considerably elevated already in utero, increased dramatically within the 1st day of postnatal life and reached adult values at the end of the 1st week. The development of hepatic glycerolkinase was compared with that of hepatic phosphoenolpyruvate carboxykinase of rat and hamster up to the 20th day of postnatal life. The different time-courses of the levels of these two enzymes before and after birth as well as the known kinetics of serum insulin, glucagon and corticosterone during that time suggested that none of these hormones is involved in the perinatal development of hepatic glycerolkinase activity. In contrast to liver, kidney glycerolkinase activity in both, rat and hamster, showed a delayed increase during the first week of postnatal life followed by a more pronounced elevation to adult values within the following 2 weeks. 2. When liver and kidney glycerolkinase activity was investigated during starvation (+/- refeeding), in alloxan diabetes(+/- insulin) and after adrenalectomy (+/- cortisol) no significant change in enzyme activity per g tissue could be detected either in liver or in kidney. However, total hepatic glycerolkinase activity was diminished during starvation as a consequence of decreasing liver weight. 3. Incorporation of U-[14C]-glycerol into CO2, lipids and glucose + glycogen by rat liver and kidney cortex slices was studied under the above gluconeogenetic conditions. Despite unchanged glycerolkinase activity in both organs, gluconeogenesis from glycerol was enhanced during starvation and in chronic alloxan diabetes, and could be reversed by refeeding and insulin replacement, respectively. 4. Feeding 20% of linolic acid to normal, alloxan-diabetic or adrenalectomized rats resulted in a significant increase in glycerolkinase activity in liver but not in kidney. 5. From the present findings it is suggested that the first step of gluconeogenesis from glycerol in liver and kidney is not influenced by glucagon, insulin and glucocorticoids, which are generally believed to regulate the rate of gluconeogenesis from non-glycerol precursors, but probably by the change in blood glycerol concentration.
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PMID:Glycerolkinase--a regulatory enzyme of gluconeogenesis? 18 91

Methods were devised or modified which made it possible to measure phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase in seven defined parts of single nephrons and in patches from thin limb and papilla areas dissected from freeze-dried microtome sections of rat kidney. All three enzymes were essentially confined to the proximal tubule. In normal kidneys, the levels were highest in the proximal convoluted tubule. Glucose-6-phosphatase was 20 times higher in the early part of the convoluted segment than in the late part of the straight segment. With one exception, in acidosis, only phosphoenolpyruvate carboxykinase increased (fourfold in the proximal convoluted segment but much less in the straight portion). In starvation, phosphoenolpyruvate carboxykinase increased about as much as in acidosis in the proximal straight tubule, but not as much in convoluted portions, whereas glucose-6-phosphatase rose modestly in both parts of the proximal tubule and fructose bisphosphatase rose only in the straight tubule, especially the early segment. It is suggested that ammoniagenesis can accompany gluconeogenesis in the proximal convoluted tubule but not in the straight segment.
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PMID:Distribution along the rat nephron of three enzymes of gluconeogenesis in acidosis and starvation. 21 58

Starvation or feeding rats on a high-protein diet, valine or isoleucine, but not leucine, increases the activity of muscle phosphoenolpyruvate carboxykinase, but has no effect on NADP+-linked malate dehydrogenase. This suggests that muscle phosphoenolpyruvate carboxykinase is involved in oxidation or conversion of some amino acids to alanine.
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PMID:The role of phosphoenolpyruvate carboxykinase in amino acid metabolism in muscle. 21 68

The effects of starvation on the acid-base status of the rat and on the glucoeogenic and ammoniagenic capacity of rat renal-cortical slices were examined. Starvation for 48 or 72 hr did not affect acid-base status, and urinary ammonia production did not change. Kidney cortical slices from starved as compared to fed rats showed increased gluconeogenic capacity when incubated with the substrated pyruvate, succinate, fumarate, malate, 2-oxyoglutarate, glutamine and glutamate. Renal cortical tissue from starved rats also had increased activity of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase. Renal cortical slices from starved rats did not differ from those from fed rats in the ability to produce ammonia from glutamine or glutamate, nor was there any difference inhe activity of glutaminase between these groups. These results show that renal gluconeogenic capacity is increased in starved rats in the absence of systemic acidosis, and starvation does not lead to an increase in urinary ammonia excretion or renal ammoniagenic capacity.
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PMID:Effect of starvation on renal metabolism in the rat. 24 54

Yeast mutant lacking proteinase B activity have been isolated [Wolf, D. H. and Ehmann, C. (1978) FEBS Lett. 92, 121--124]. One of these mutants (HP232) is characterized in detail. Absence of the vacuolar localized enzyme is confirmed by checking for proteinase B activity in isolated mutant vacuoles. Defective proteinase B activity segregates 2:2 in meiotic tetrads. The mutation is shown to be recessive. Mutant proteinase B activity is not only absent against the synthetic substrate. Azocoll, but also against the physiological substrate pre-chitin synthetase, cytoplasmic malate dehydrogenase and fructose-1,6-bisphosphatase. The mutant shows normal vegetative growth, a phenomenon not consistent with the idea that proteinase B might be the activating principle of chitin synthetase zymogen in vivo. Fluorescence microscopy shows normal chitin insertion. Enzymes underlying carbon-catabolite inactivation in wild-type cells (a mechanism proposed to be possibly triggered by proteinase B) such as cytoplasmic malate dehydrogenase, fructose-1,6-bisphosphatase, phosphoenolpyruvate carboxykinase and isocitrate lyase, are inactivated also in the mutant. NADP-dependent glutamate dehydrogenase, which is found to be inactivated in glucose-starved wild-type cells, proceeds normally in the mutant. Mutant cells show more than 40% reduced protein degradation under starvation conditions. Sporulating diploids, homozygous for proteinase B absence, also exhibit an approximately 40% reduced protein degradation as compared to homozygous wild-type diploids or diploids heterozygous for the mutant gene. The time of the appearance of the first ascospores of diploid cells, homozygous for proteinase B deficiency, is delayed about 50% and sporulation frequency is reduced to about the same extent as compared to homozygous wild-type diploids or diploids heterozygous for the mutant gene.
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PMID:Studies on a proteinase B mutant of yeast. 38 14

Male rats were weaned normally (NW; day 30 after birth) or prematurely (PW; day 18) to a Purina Chow diet. Serum cholesterol levels and the activities of some enzymes of fatty acid and glucose metabolism were determined when the animals were 6 and 10 months old and, in the older group, also after 2 days of starvation. Blood cholesterol levels rose with age and at 10 months were higher in PW than NW rats. This difference disappeared after starvation. Hepatic pyruvate kinase (PK) activity was the same in fed NW and PW animals but was significantly higher in starved PW than NW rats. Hepatic phosphoenolpyruvate carboxykinase (PEPcK) activity was lower in NW than in PW rats, but this difference disappeared on starvation. In white fat, starvation caused a fall in PEPcK activity in both groups. In general, the effect of starvation did not accentuate the differences between the two groups. However, PEPcK activity in white fat increased with age about fourfold.
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PMID:The response of adult rats weaned prematurely and normally to starvation. 43 96


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