Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

Inclusion bodies containing glycogen-enzymes were found in 30 to 60% of type 2 fibres of tenotomized calf muscles (m. gastrocnemius, m. soleus, m. plantaris) in rats, using histochemical reactions. The bodies appeared within 1 week after the tenotomy and were localized both in the central and the subsarcolemmal regions and rarely extruded into the extracellular space. These aggregates are 3 to 15 microns in length and 2 to 11 microns in diameter. In addition to glycogen, these bodies also contained various enzymes of the glycogen metabolism such as phosphorylase, a branching enzyme, and glucose-6-phosphatase, but showed no NADH-reductase, lactate dehydrogenase, or myofibrillar ATP-ase activity. The results indicate that glycogen-enzymes containing bodies are a degenerative phenomenon, which occurs only in type 2 fibres of the tenotomized muscles.
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PMID:Glycogen-enzymes containing bodies in type 2 fibres of tenotomized muscles in the rat. 255 27

A dimethoxy derivative of leucocyandin 3-O-beta-D-galactosyl cellobioside isolated from the bark of F. bengalensis Linn demonstrated antidiabetic action. On oral administration, it decreased blood sugar very significantly both in normal and moderately diabetic rats and increased serum insulin significantly in the latter at a dosage of 250 mg/kg for a 2 hr period. During one month treatment of the diabetic rats orally with the active principle, at a dosage of 100 mg/kg, there was a significant decrease in blood and urine sugar, certain lipid components in serum and tissues and glucose-6-phosphatase activity in liver, but significant increase in body weight and the activities of hexokinase and HMGCOA reductase in tissues as compared to diabetic control. The mechanism of action of the principle may be related to its protective/inhibitory action against the insulin degradative processes.
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PMID:Antidiabetic effect of a leucocyanidin derivative isolated from the bark of Ficus bengalensis Linn. 263 65

The distribution of hepatic binding sites for the calcium-mobilizing second messenger, inositol 1,4,5-trisphosphate (IP3), was analyzed in subcellular fractions of the rat liver by binding studies with [32P]IP3 and compared with the Ca2+ release elicited by IP3 in each fraction. Three major subcellular fractions enriched in plasma membrane, mitochondria, and endoplasmic reticulum were characterized for their 5'-nucleotidase, glucose-6-phosphatase, succinate reductase, and angiotensin II binding activities. The fraction enriched in plasma membrane showed 7- and 20-fold increases in IP3 binding capacity over those enriched in endoplasmic reticulum and mitochondria, respectively, and contained a single class of high-affinity binding sites with Kd of 1.7 +/- 1.0 nM and concentration of 239 +/- 91 fmol/mg protein. IP3 binding reached equilibrium in 30 min at 0 degrees C, and the half-time of dissociation was about 15 min. The specificity of the IP3 binding sites was indicated by their markedly lower affinities for inositol 1-phosphate, phytic acid, fructose 1,6-bisphosphate, 2,3-bisphosphoglycerate, and inositol 1,3,4,5-tetrakisphosphate. The Ca2+-releasing activity of IP3 in the subcellular fractions was monitored with the fluorescent indicator, Fura-2. All three fractions showed ATP-dependent Ca2+ uptake and rapidly released Ca2+ in response in IP3. The fraction enriched in plasma membrane was the most active in this regard, releasing 174 +/- 67 pmol Ca2+/mg of protein compared to 45 +/- 10 and 48 +/- 7 pmol/mg protein for the fractions enriched in endoplasmic reticulum and mitochondria, respectively. These data suggest that the [32P]IP3 binding sites represent specific intracellular receptors through which IP3 mobilizes Ca2+ from a storage site associated (or co-purifying) with the plasma membrane of the rat liver. It is likely that a specialized vesicular system (to which IP3 can bind and trigger the release of Ca2+) is located in close proximity with the plasma membrane and is thus adjacent to the site at which IP3 is produced during stimulation of the hepatocyte by Ca2+-mobilizing hormones.
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PMID:Characterization of inositol 1,4,5-trisphosphate receptors and calcium mobilization in a hepatic plasma membrane fraction. 283 98

We aim to evaluate the effects of phenobarbital (PB) on the liver drug metabolism, NADPH production capacity and terminal gluconeogenic enzyme, glucose-6-phosphatase (G6Pase) activity in the diabetic state associated with genetic obesity in mice. The results showed that PB treatment increased the amount of liver total cytochrome P450 (cytP450), a drug metabolizing monooxygenase enzyme in genetically obese, hyperglycemic (ob/ob) mice 6-fold and the total activities of other monooxygenase enzymes NADPH cytP450 reductase and 7-ethoxyresorufin O-deethylase (ERDE) 2- and 6.5-fold, respectively. In addition, the regimen increased the liver total activities of two NADPH generating enzymes, 6-phosphogluconate dehydrogenase (6PGDH) and malic enzyme (ME) in obese mice suggesting that the regimen enhanced liver NADPH production capacity in the animals. The data further showed that PB treatment decreased the high hepatic G6Pase activity in obese mice. Both enhanced NADPH generating enzyme activities and lowered G6Pase activity may suppress hepatic glucose output. Since NADPH is required for drug oxidation reactions as a reducing cofactor, high NADPH generating capacity may facilitate liver drug metabolism in vivo. Although the diabetic state in obese mice differs somewhat from that seen in non-insulin dependent diabetic subjects (NIDDs), these findings provide some knowledge about the possible biochemical mechanisms whereby PB treatment normalizes drug metabolism and glycemic control in NIDDs, as has been noted in previous studies.
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PMID:Hepatic drug metabolism and the activities of NADPH generating enzymes and glucose-6-phosphatase in phenobarbital treated genetically obese (ob/ob) mice. 283 24

The cholesterol content of rat liver microsomal membranes was modified in vitro by incubating microsomes and cytosol with liposomes prepared by sonication of microsomal lipids and cholesterol. In this way, the cholesterol to phospholipid molar ratio was increased from 0.11-0.13 in untreated microsomes to a maximal of 0.8 in treated ones. Cholesterol incorporation in microsomes produced an increase in the diphenyl-hexatriene steady-state fluorescence anisotropy and a decrease in the efficiency of pyrene-excimer formation which indicated a decrease in the rotational and translational mobility, respectively, of these probes in the membranes lipid phase. Cholesterol incorporation in microsomes did not affect significantly the glucose-6-phosphatase activity in 0.1% Triton X-100 totally disrupted microsomes, but diminished the glucose-6-phosphatase activity of 'intact' microsomes. This indicates that possibly the glucose 6-phosphate translocation across the microsomal membrane is impeded by an increase in the membrane apparent 'microviscosity'. Cholesterol incorporation in microsomes decreased NADH-cytochrome c reductase without affecting NADH-ferricyanide reductase activity. The delta 9 desaturation reaction rate was enhanced by cholesterol incorporation at low but not at high palmitic acid substrate concentration. delta 5 and delta 6 desaturase reaction-rates were increased both at low and high fatty acid substrate concentrations. These results suggest that a mechanism involving fatty acid desaturase enzymes, might exist to self-regulate the microsomal membrane lipid phase 'fluidity' in the rat liver.
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PMID:In vitro modification of cholesterol content of rat liver microsomes. Effects upon membrane 'fluidity' and activities of glucose-6-phosphatase and fatty acid desaturation systems. 299 32

Several subpopulations of hepatocytes with increasing cell diameters were isolated, the smaller cells were attributed to the periportal area, the larger ones to the perivenous region. Profiles of total cytochrome P-450, benzphetamine N-demethylation and ethoxyresorufin O-deethylation, cytochrome c-reductase, glucose-6-phosphatase and GPT activities were determined. With adult hepatocytes an increasing cytochrome P-450 concentration with increasing cell diameter could be observed, paralleled by increasing activities of monooxygenases. Glucose-6-phosphatase and GPT also revealed increasing activities with increasing cell diameter, but cytochrome c-reductase did not show a distinct zonation. Immature hepatocytes (age 11-15 days) were smaller, more fragile, and could not be isolated with the same enzyme solution as adult hepatocytes. They did not show any zonation of cytochrome P-450 whereas the zonation of the monooxygenases was almost fully developed. For cytochrome c-reductase a zonation with higher activities in the perivenous cells could be demonstrated, in contrast to the lack of zonation in adult rats. Glucose-6-phosphatase showed a decline with increasing cell diameter in immature hepatocytes, whereas GPT did not show any zonation. In rats aged 20 days the zonation of these parameters in liver was in between younger and older animals.
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PMID:Separation of immature and adult rat hepatocytes into distinct subpopulations by centrifugal elutriation. 300 35

Aniline hydroxylase, glucose-6-phosphatase, NADPH- and NADH-cytochrome C reductase activities were measured in liver microsomes prepared from four groups of female mice. Mice were fed either control diets alone or KCN (0.357, microgram/kg body wt/day) supplemented diets or control diets plus AFB1 (0.35 microgram/kg body wt/day) administration (ip) on the 8, 9 and 10th day or the KCN supplemented diet plus AFB, administration (ip) on the 8, 9 and 10th day. KCN and AFB1 consistently elevated the activities of the enzymes. Simultaneous administration of both toxins potentiated their effects on the enzymes with the exception of glucose-6-phosphatase. Increases in microsomal protein/liver wt ratios, liver wt/body wt ratios and these enzyme activities were probably indicative of microsomal enzyme induction.
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PMID:Effect of aflatoxin B1 on some liver microsomal enzymes in mice fed cyanide supplemented diets. 310 4

Hepatocytes were isolated from immature and adult rat liver by retrograde perfusion with calcium free buffer, followed by enzymic digestion, and separated into subpopulations by centrifugal elutriation. Several subpopulations with increasing cell diameters were distinguished. The smaller cells were attributed to the periportal area, the larger ones to the perivenous (centrilobular) region. Profiles of total cytochrome P-450 concentration, benzphetamine N-demethylation and ethoxyresorufin O-deethylation, NADPH-cytochrome c-reductase, glucose-6-phosphatase and glutamate-pyruvate-transaminase activities were determined in all subpopulations. With adult hepatocytes an increasing cytochrome P-450 concentration with increasing cell diameter (increasing from periportal to perivenous hepatocytes) could be observed, paralleled by increasing activities of benzphetamine N-demethylation and ethoxyresorufin O-deethylation activities. While NADPH-cytochrome c-reductase did not show a distinct zonation, glucose-6-phosphatase and glutamate-pyruvate-transaminase revealed increasing activities with increasing cell diameter. Immature hepatocytes (rats aged 11-15 days) were smaller, and more fragile. They could not be isolated with the same enzyme solution as adult hepatocytes and they did not show any zonation of cytochrome P-450 concentration, although the zonation of benzphetamine N-demethylation and ethoxyresorufin O-deethylation was almost fully developed. For NADPH-cytochrome c-reductase a zonation with higher activities in the perivenous cells could be demonstrated, in contrast to the lack of zonation in adult rats. Glucose-6-phosphatase activity showed a decline with increasing cell diameter in immature hepatocytes, whereas glutamate-pyruvate-transaminase activity did not show any zonation. In rats aged 20 days the zonation of these parameters in liver was in between that of younger and older animals. Zonation of the liver lobule develops postnatally with individual patterns for the different parameters.
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PMID:Separation and characterization of hepatocytes from immature and adult rats into distinct subpopulations by centrifugal elutriation. 322 57

Hydroxylation of dimethylaniline in rabbit liver microsomes is accompanied by inactivation of cytochrome P-450 and the formation of products inhibiting the catalytic activity of non-inactivated cytochrome P-450. Other enzymes and electron carriers of microsomal membrane (cytochrome b5, NADH-ferricyanide reductase, NADPH-cytochrome c and NADPH-cytochrome P-450 reductases) as well as glucose-6-phosphatase were not inactivated in the course of the monooxygenase reactions. Phospholipids and microsomal membrane proteins were also unaffected thereby. Consequently, the changes in the microsomal membrane during cytochrome P-450 dependent monooxygenase system functioning are confined to the inactivation of cytochrome P-450.
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PMID:[Effect of monooxygenase reactions catalyzed by cytochrome P-450 on the microsomal membrane]. 366 48

The effects of carbon disulfide (CS2) on the liver microsomal drug-metabolizing enzyme system and other enzyme activities were studied 1 hr after the oral administration of 3-300 mg/kg of CS2 in mice. Considerable decreases in drug-metabolizing enzyme activities (such as hydroxylation of aniline, O-dealkylation of p-nitroanisole, 7-ethoxycoumarin and 7-ethoxyresorufin, and N-demethylation of N,N-dimethylaniline), NADPH-cytochrome P-450 reductase (but not NADPH-cytochrome c reductase), and P-450-associated peroxidase activities were already observed at 3 and 30 mg/kg of CS2, dose dependently. At the same dosage levels, the magnitudes of microsomal spectral changes induced by aniline and nicotinamide (type 2 substrates), but not those induced by hexobarbital and SKF-525A (type 1 substrates), were also reduced to a considerable extent. The degrees of these alterations were all greater than that of the measurable loss of P-450 content, i.e. the loss of functional activity of P-450 was much greater than simply expected from the apparent decrease in the hemoprotein content. Cytochrome b5 content and NADH-ferricyanide reductase activity were unchanged at 30 and 300 mg/kg of CS2, although NADH-cytochrome c reductase activity was increased at the latter dose. The following enzyme activities did not change significantly at up to 300 mg/kg of CS2: flavin-containing monooxygenase, UDP-glucuronyl transferase, glucose-6-phosphatase and heme oxygenase in microsomes, and glutathione S-transferases in the soluble fraction. Microsomal conjugated diene levels and liver glutathione content were also unchanged. These observations support the theory that P-450 is a sensitive and selective site for CS2 action, where CS2 itself is bioactivated. It was also shown that the loss of P-450 was reversible after a single, or repeated, administration of CS2.
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PMID:Early, selective and reversible suppression of cytochrome P-450-dependent monooxygenase of liver microsomes following the administration of low doses of carbon disulfide in mice. 377 18


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