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Query: EC:3.1.3.9 (glucose-6-phosphatase)
 3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies showed that livers from carnivorous birds have a higher gluconeogenic capacity and higher levels of gluconeogenic enzymes than livers from granivorous birds. In this work we compare the effects of fasting and adrenalectomy on gluconeogenesis. Fasting in the chicken elicited increased rates of incorporation of 14C from alanine into blood glucose, increased gluconeogenesis in liver slices, and increased activities of four gluconeogenic enzymes: glucose-6-phosphatase, phosphoenolpyruvate carboxykinase, alanine aminotransferase, and aspartate aminotransferase. These responses in the chicken resemble those observed in fasted rodents. In marked contrast, fasting in black vultures induced decreased rates of incorporation of alanine label into circulating glucose, decreased gluconeogenesis in liver slices, and no change in any of the four enzymes studied. This unusual response to fasting in the carnivorous bird is probably related to the high-protein-low-carbohydrate content of the diet. Fasted adrenalectomized birds (granivorous and carnivorous) had reduced rates of in vivo glucose synthesis, decreased liver gluconeogenesis, and lower activity of glucose-6-phosphatase and aspartate aminotransferase, without change in phosphoenolpyruvate carboxykinase and alanine aminotransferase activities.
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PMID:Fasting, adrenalectomy, and gluconeogenesis in the chicken and a carnivorous bird. 20 1

The activities of pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G6Pase), and glycogen synthetase (GS) were determined in the cancerous and in the apparently uninvolved (host) regions of livers from primary hepatoma patients as well as in normal adult human livers and human fetal livers. The activities of these enzymes were also assayed in a fairly fast-growing, 3'-methyl-4-dimethylaminoazobenzene-induced transplantable rat hepatoma and in hepatoma cell lines derived from both rat and human tumors. In the human hepatoma, as in the rat hepatoma, the activities of PC, PEPCK, and G6Pase were considerably reduced, compared to those in the host liver. The activities of both the a (glucose 6-phosphate-independent) and b (glucose 6-phosphate-dependent) forms of GS were also lower in human and rat hepatomas than in the respective host livers. Activities of PC, PEPCK, and G6Pase in the human hepatomas were often comparable with those of fetal livers. In rat and human hepatoma cells, the activities of PC, PEPCK, and G6Pase were similar to or lower than the activities in the respective hepatomas; the activities of GS a were also similar to those in the hepatoma, whereas the activities of GS b were somewhat higher.
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PMID:Activities of key gluconeogenic enzymes and glycogen synthase in rat and human livers, hepatomas, and hepatoma cell cultures. 20 62

Liver glucose-6-phosphatase and phosphoenolpyruvate carboxykinase activities were increased in the postmature rat fetus (23.5 day old) when compared to term rat fetus (21.5 day old). Postmaturity was without effect on liver phosphorylase activity. The three liver enzyme activities were also determined in normal 2 day old neonates. These results are correlated with the mobilisation of fetal liver glycogen occuring during postmaturity in the rat and are discussed in relation to the secretory pattern of the pancreatic hormones.
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PMID:Postmaturity in the rat: phosphorylase, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase activities in the fetal liver. 20 99

The activities of gluconeogenic enzymes of the rat kidney cortex was studied after exposure to lowered atmospheric pressure (200 mm Hg) for 3 hours. The hypoxic stress was found to cause an increase in the activities of phosphoenolpyruvate carboxykinase and alanine aminotransferase, but failed to affect significantly the activities of fructose-1,6-diphosphatase, glucose-6-phosphatase, and aspartate aminotranspherase. The ratio of glucose-6-phosphatase/hexokinase activities was increased under these conditions.
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PMID:[Activity of gluconeogenetic enzymes of rat kidney cortex during acute hypoxia]. 20 72

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

During the first 72 h after 67% partial hepatectomy of female Wistar rats (160 g) the specific activities [mumol X min-1 X (g liver)-1] of the glucogenic glucose-6-phosphatase and fructose-bisphosphatase and of the glycolytic hexokinase and 6-phosphofructokinase remained essentially constant. However, the activity of the glycolytic pyruvate kinase (L- plus M2-type) was decreased slightly and that of glucokinase was decreased markedly to below 30%, while the glucogenic phosphoenolpyruvate carboxykinase was increased to over 200%. Between 10 and 40 h after partial hepatectomy, when the proliferation started in the periportal area, a shift of the glucogenic glucose-6-phosphatase-rich zone from its normal periportal to an intermediate or even perivenous position was observed histochemically. After 48 h, when the proliferation was no longer restricted to the periportal zone, the normal glucose-6-phosphatase zonation (as before partial hepatectomy) was restored. Glycogen was degraded rapidly during the first 4 h after operation; it was later repeatedly resynthesized and degraded in correlation with the feeding rhythm of the animals. The zonation of glycogen metabolism was in accord with the observed zonation of glucose-6-phosphatase.
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PMID:Increase of the gluconeogenic and decrease of the glycolytic capacity of rat liver with a change of the metabolic zonation after partial hepatectomy. 21 1

Xenopus laevis (Daudin) adult specimens were submitted to hypophysectomy. Although the operation resulted subtotal, it served the purpose of removing the prolactin-producing cells, whereby the involvement of endogenous prolactin in osmoregulation phenomena was excluded. In the operated animals treated with ovine prolactin the following metabolic parameters, which are closely dependent upon interrenal activity, were estimated: 1) intestine alkaline phosphomonoesterase activity (E.C. 3.1.3.1); 2) liver glycogen level; 3) glucose-6-phosphatase (E.C. 3.1.3.9.) and phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32.) in the liver; 4) blood glucose level; 5) blood ammonia and urea levels; 6) carbamoylphosphate synthetase activity in the liver (E.C. 2.7.2.a); 7) muscle sodium and potassium levels. The above metabolic parameters were found to be pressed by subtotal hypophysectomy and after subsequent prolactin treatment showed the tendency to go back to values similar to those of control animals.
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PMID:Biochemical data on subtotally hypophysectomized Xenopus laevis (Daudin) adult specimens treated or not with prolactin. 21 25

Activities of the 4 hepatic gluconeogenic enzymes: glucose-6-phosphatase, fructose-1,6-diphosphatase, pyruvate carboxylase, particulate and cytosolic phosphoenolpyruvate carboxykinase (PEPCK) have been measured in fetal rabbits (22, 25, 28, 30 and 31 days of gestation) and in fasted or suckling newborns (1 and 2 days after birth). Between days 25 and 31 of gestation, fructose 1,6-diphosphatase and particulate PEPCK activities represent 50% of adult (pregnant female) activities, while pyruvate carboxylase is present at adult values during the same period. Glucose-6-phosphatase is low and cytosolic PEPCK absent in fetal liver until 30 days of gestation and increase significantly during the day preceding birth. Al the enzymes show a further increase after birth independently of the nutritional status of the animals (starved or suckling).
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PMID:Perinatal development of glucoeneogenic enzymes in rabbit liver. 22 57

The effect of fasting and fasting and refeeding on hepatic and renal gluconeogenic enzyme activities were studied in six-week-old chickens (Gallus domesticus: New Hampshire male x Columbian female). Hepatic pyruvate carboxylase appeared not to be affected by fasting, but the renal enzyme activity increased in four-day fasted chickens. The hepatic mitochondrial and cytosolic phosphoenolpyruvate carboxykinases were essentially not affected by fasting. The renal mitochondrial phosphoenolpyruvate carboxykinase showed a slight increase in activity only after a four-day fast, but the cytosolic enzyme activity increased markedly already after a two-day fast. Also the activities of the hepatic and renal fructose-1,6-diphosphatase and glucose-6-phosphatase increased markedly on fasting. Refeeding for four days after a four-day fast returned these enzyme activities to near control values.
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PMID:Effect of fasting and fasting and refeeding on hepatic and renal gluconeogenic enzymes in the chicken. 22 47

Intrauterine growth retardation was induced in rats by ligation of the artery of one of both uterine horns. Activities of pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-diphosphatase and glucose-6-phosphatase in liver were measured at 0, 1, 3 and 6 h after delivery in newborn rats from normal and sham-operated litters, and from ligated and contralateral uterine horns. Lower activities of fructose-1,6-diphosphatase were found in small-for-gestational-age animals in comparison with animals from contralateral horns. When small-for-gestational-age animals were compared with animals from sham litters (which could be regarded as more satisfactory controls), the activities of two other gluconeogenic enzymes (pyruvate carboxylase and glucose-6-phosphatase) appeared to be lower as well. It is concluded that a delay in the development of these gluconeogenic enzymes could play a role in neonatal hypoglycemia in small-for-gestational-age rats.
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PMID:Gluconeogenic key enzymes in normal and intrauterine growth-retarded newborn rats. 23 14


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