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At least 289 records · Page 16Linked to original sources
PubMed1991

Streptozotocin-induced suppression of FAD-linked glycerophosphate dehydrogenase in pancreatic islets of adult rats.

Injection of streptozotocin (30-40 mg/kg body weight) to adult rats caused within 4-6 days a sizeable decrease in the activity of FAD-linked glycerophosphate dehydrogenase in pancreatic islets, with little change in either glutamate dehydrogenase or 2-oxoglutarate dehydrogenase activity. The severity of the enzymatic defect was related to that of the diabetic state, although a decreased enzymic activity was also observed in islets from virtually normoglycemic animals examined 2-3 weeks after streptozotocin injection. The administration of nicotinamide prior to that of streptozotocin prevented the change in enzymic activity. It is proposed that the enzymatic defect, rather than being attributable to a genomic effect of streptozotocin, may reflect the preferential impairment of a subpopulation of pancreatic B-cells.

Animals↗
PubMed1991

[Insular modifications in glycerophosphate dehydrogenase in diabetes].

In the model of non-insulin-dependent diabetes found in adult rats injected with streptozotocin during the neonatal period, the activity of the mitochondrial glycerophosphate dehydrogenase is severely reduced in pancreatic islets. This coincides with a decreased contribution of aerobic to total glycolysis in intact islets and could account for the preferential impairment of the insulin secretory response to glucose.

Animals↗
PubMed1989

Increase in alpha-glycerophosphate dehydrogenase and other oxidoreductase activities of hepatic mitochondria on administration of vanadate to the rat.

Liver mitochondria isolated from vanadate-administered rats showed increased (20-25%) rates of oxidation of both NAD(+)-linked substrates and succinate. Respiratory control index and ADP/O were unaffected by the treatment. Dormant and uncoupler-stimulated ATPase activity also was not affected by vanadate administration. Membrane-bound, electron-transport-linked dehydrogenase activities (both NAD(+)- and succinate-dependent) increased by 15-20% on vanadate treatment. Mitochondrial alpha-glycerophosphate dehydrogenase activity increased by 50% on vanadate administration. The above effects of vanadate on oxidoreductase activities could be prevented by the prior administration of antagonists to alpha-adrenergic receptors. Substrate-dependent H2O2 generation by mitochondria also showed an increase on vanadate administration.

Animals↗
PubMed1989

Sex-related differences in the activity of liver mitochondrial alpha-glycerophosphate dehydrogenase in the rat.

The rat liver mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) is an enzyme that markedly responds to thyroid hormone administration. Its activity is considered a good index of thyroid status in peripheral tissues. In this study alpha-GPD activity and the binding characteristics of nuclear T3 receptors (maximal binding capacity, MBC, and affinity constant, Ka) were compared in male and female rats. Basal alpha-GPD activity in adult females was significantly higher than in the age-matched males. The same difference was observed in immature animals. The cyclic physiological variations in the ovarian steroid hormones during the estrous cycle did not significantly affect alpha-GPD activity, MBC or Ka. Orchiectomy or replacement doses of testosterone administered to orchiectomized rats, had no effect on alpha-GPD activity compared to sham-operated normal males. In females, neither oophorectomy nor testosterone injection to oophorectomized animals induced changes in the enzyme activity. Liver nuclear T3-content, MBC and Ka revealed no systematic differences in both sexes. The T3-induced alpha-GPD activity after a single large dose of T3 designed to fully saturate the nuclear sites for a 24 h period, was significantly higher in female compared to male rats. The kinetics of alpha-GPD showed an identical Km in both sexes, while Vmax was significantly higher in the females. The data suggest that the factors leading to the different activity of alpha-GPD in both sexes, although unknown, may be not related to the sex-hormone differences.

Animals↗
PubMed1987

Nucleotide sequence and hormonal regulation of mouse glycerophosphate dehydrogenase mRNA during adipocyte and muscle cell differentiation.

We have studied the structure and regulation of glycerophosphate dehydrogenase (GPD) mRNA during mouse adipocyte and muscle cell differentiation. This message has a size of 2.8 kilobases that includes a coding segment of 1050 bases and a large untranslated 3' end of about 1700 bases. There is a high degree of amino acid homology (91%) between the mouse adipocyte and rabbit muscle GPD proteins. GPD mRNA is not detected in myoblasts, but, as in adipogenesis, it is expressed upon differentiation into myotubes. The modulation of GPD mRNA by cyclic AMP analogues and tumor necrosis factor has been examined in both adipocytes and myotubes. Dibutyryl cAMP or 8-bromo-cAMP causes a large reduction of GPD mRNA levels in both cell types, with less than 20% remaining after 18 h of treatment. Tumor necrosis factor effects a dramatic and rapid reduction in GPD mRNA in fat cells and a slower but significant decrease in the level of this mRNA in muscle cells. These results indicate that GPD gene expression is linked to cell differentiation in both fat and muscle cells, and suggest certain similarities in hormonal modulation in both cell types.

Adipose Tissue↗
PubMed1987

Induction of hepatic mitochondrial alpha-glycerophosphate dehydrogenase by L-triiodothyronine in Singi fish (Heteropneustes fossilis Bloch).

A single injection of L-triiodothyronine (T3) in different doses (0.25, 0.5, 5, 20 and 50 micrograms/g) increased the hepatic mitochondrial cytochrome-linked alpha-glycerophosphate dehydrogenase (alpha-GPD) activity and mitochondrial protein content of Singi fish, as observed on the 3rd day. A non-linear dose-response relationship with respect to enzyme activity was observed with different doses of T3. A low dose of 0.1 micrograms of T3 per g failed to cause any change in alpha-GPD activity and mitochondrial protein content of the liver. The enhancement of alpha-GPD activity over the control level with a low and a high dose of T3, viz., 0.5 and 5 micrograms/g, was followed from the 1st to the 7th day, when it was found that enzyme activity reached the maximum level on the 3rd day and then gradually declined to the control value on the 7th day. The percentage increase in enzyme activity with 5 micrograms/g was higher than that with 0.5 microgram/g from the 2nd to 5th day. Compared to the control, these two doses of T3 caused an increase in alpha-GPD activity from the 1st to the 6th day. Cycloheximide inhibited the T3-induced increase in alpha-GPD activity, mitochondrial and total protein content of liver. Immersion of Singi fishes in thiourea-containing (1 mg/ml) medium for 30 days showed a fall in hepatic alpha-GPD activity in comparison to the euthyroid control. A single injection of T3 (0.5 microgram/g) to the hypothyroid fish recovered alpha-GPD activity to more than the euthyroid control level. An increase in mitochondrial protein content in the T3-injected hypothyroid fish has been observed. DNA content of the fish liver remained unchanged in every experimental condition. The results thus showed the significant responsiveness of the fish liver to thyroid hormone.

Animals↗
PubMed1981

[Effect of hydrocortisone on alpha-glycerophosphate dehydrogenase activity in KOX-1 and mouse glioblastoma EPNT-5 cells].

A comparative cytochemical investigation for alpha-glycerophosphate dehydrogenase (alpha-GPhD) activity in transplanted cellular line of mouse glioblastoma (EPNT-5) and KOX-1 was performed under normal conditions and under hydrocortisone effect. In glioblastoma EPNT-5 cells a high alpha-GPhD activity was revealed. The enzymatic activity was found to correspond to the dynamics of cell multiplication. Under the effect of hydrocortisone, alpha-GPhD activity demonstrated a two-fold increase, while alpha-GPhD activity in KOX-1 cells was very low, and hydrocortisone did not induce its increase. The data obtained supported the view on the glial nature of the transplanted ćpHT-5 line and demonstrated that the glial elements preserved their specific peculiarities at a prolonged cultivation.

9,10-Dimethyl-1,2-benzanthracene↗
PubMedDate not supplied

[Effect of somatotropin on the activity of mitochondrial alpha-glycerophosphate dehydrogenase in the liver of rats with hypo- and hyperthyroidism].

The activity of mitochondrial alpha-glycerophosphate dehydrogenase in the liver of rats with hypothyrosis (two weeks after total thyroidectomy) is 36% of the normal level; in rats with hyperthyrosis (three weeks after subcutaneous implantation 2 mg of l-thyroxin on a kaolin base) it is 7.4 times as high. Bovine somatotropin (0.5 mg per 100 g of body mass) injected subcutaneously for 10 days has no effect on the enzyme activity in intact rats and in rats with hypothyrosis. In animals with hyperthyrosis somatotropin produces a 37% decrease in the enhance activity of the enzyme. Somatotropin fully normalizes a 25% increased amount of protein in the liver mitochondrial fractions of rats with hyperthyrosis.

Animals↗
PubMed1982

Cytosolic alpha-glycerophosphate and lactate dehydrogenase in the lung in endotoxin shock.

The lung produces lactate aerobically. In endotoxin shock in aerobic production of lactate increases further. We have investigated an enzymic mechanism for the aerobic lactate in the lung. Since an inadequacy of the cytoplasmic hydrogen "shuttle" enzyme alpha-glycerophosphate dehydrogenase (alpha-GPDH) and/or the presence of lactate dehydrogenase (LDH) in excess of alpha-GPDH can cause aerobic formation lactate, we measured alpha-GPDH and LDH in mitochondria-free cytoplasmic fractions of lungs from control and endotoxic shock rats. The shock was induced by an intravenous injection of E coli endotoxin, 16 mg/kg. In lungs of control or endotoxic shock rats, alpha-GPDH was only 10% of the LDH activity. The low absolute levels of alpha-GPDH and the relative deficiency of this enzyme, compared to LDH in the lungs of control and endotoxic shock rats, can potentially contribute to aerobic lactate production.

Aerobiosis↗
PubMed1995

Effect of cultivation conditions on glycerophosphate oxidase production by a mutant strain of Aerococcus viridans.

The effect of different concentrations of carbon source (lactose) and inducer (glycerol) on biomass and glycerophosphate oxidase (GPO) production by mutant strain of Aerococcus viridans 1509 was tested. The best combination of lactose and glycerol concentrations for good enzyme productivity was 0.5% lactose and 2.5% glycerol. Further improvement of GPO levels was achieved after scaling-up of the bioprocess and cultivation of the cells in a 3 liter laboratory bioreactor. Using 4.5 x 10(-5) m3 s-1 air flow rate during growth, GPO activity increased 20-times in comparison with cultivation in flasks.

Culture Media↗
PubMed1994

[The cytochemical determination of alpha-glycerophosphate dehydrogenase and adenosine triphosphatase in the peripheral blood lymphocytes of patients with hepatobiliary system pathology].

In patients with pancreatic head cancer and virus hepatitis the lowest values of alpha glycerophosphate dehydrogenase and adenosine triphosphatase in the peripheric blood lymphocytes were determined. The dynamic study of these values in patients with pathology of liver and biliary ducts permits to estimate the disease severity course and equally with other clinico-laboratory data may have prognostic significance.

Adenosine Triphosphatases↗
PubMed1994

Purification and characterization of glycerophosphate acyltransferase from rat liver mitochondria.

Glycerophosphate acyltransferase (GAT) catalyzes the conversion of sn-glycerol 3-phosphate to lysophosphatidic acid (LPA), the first and committed step of triacylglycerol and phospholipid synthesis. In spite of the important regulatory roles GAT may play in this biosynthetic pathway, little information is available on the structure, biochemical properties, and regulation of GAT from eukaryotic cells. We solubilized GAT from rat liver mitochondrial membranes and purified it to an apparent homogeneity by hydroxylapatite chromatography, preparative isoelectric focusing, and gel filtration. The enzyme is composed of a single polypeptide of 85 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography of the native protein. The GAT activity was completely lost during the purification procedure and required addition of exogenous phospholipids for its reconstitution. Since a high phospholipid to detergent ratio was needed for full reactivation, it is concluded that GAT requires "lipid boundary" for reconstitution. The ability of different phospholipids to reactivate GAT decreased in the following order: phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), asolectin, phosphatidylinositol (PI), phosphatidylserine (PS), and cardiolipin. 1,2-Dioleoyl derivatives of PG and PE were more effective in reconstituting the GAT activity than corresponding dipalmitoyl derivatives. The GAT activation was further increased by using a combination of PG and PE or PG and PC. Regardless of the phospholipid used for reconstitution, palmitoyl-CoA was the best acyl donor and LPA was the only reaction product.

Animals↗
PubMed1976

Purification of alpha-glycerophosphate dehydrogenase from Drosophila melanogaster.

A simple procedure has been devised for the purification of alpha-glycerophosphate dehydrogenase (EC 1.1.1.8) FROM Drosophila melanogaster. The method involves substrate elution of the enzyme from a carboxymethyl cellulose column, followed by salt elution from agarose-hexane-AMP and DEAE columns. The procedure requires only 3 days to complete, results in high yield, and preparations that appear homogeneous by several criteria. A subunit molecular weight of 31 700 was obtained by sodium dodecyl sulphate electrophoresis in 10% acrylamide gels. This value is half that published for the native enzyme, confirming the homodimeric structure of this enzyme suggested by genetic evidence.

Animals↗
PubMed1993

Increased activity of FAD-linked glycerophosphate dehydrogenase in pancreatic islets of BB rats.

In several animal models of non-insulin-dependent diabetes, a decreased activity of FAD-linked glycerophosphate dehydrogenase was recently documented in pancreatic islet, but not liver, homogenates. The present study reveals that, on the contrary, the activity of the same mitochondrial enzyme is increased in islet, but not liver or spleen, homogenates of BB, as compared to BW, rats examined before the onset of severe hyperglycemia in this animal model of autoimmune insulin-dependent diabetes.

Animals↗
PubMed1973

Effect of chronic ethanol feeding on hepatic microsomal glycerophosphate acyltransferase activity.

The activity and submicrosomal distribution of alpha-glycerophosphate acyltransferase (GPAT) were studied in rats fed ethanol for 6 wk. GPAT activity was also measured in rats after 10 days of alcohol feeding, 22 days of phenobarbital administration, or 24 days on a high fat (71% of total calories) diet. After 6 wk of ethanol feeding, GPAT activity was increased 73% when expressed per milligram of protein and 133% when expressed per 100 g of body weight (P < 0.005). GPAT activity was more abundant in the smooth than in the rough microsomes of both control and ethanol-fed rats when expressed per milligram of microsomal protein and when expressed per gram of liver; the smooth microsomes accounted for most of the increased GPAT activity after ethanol. 10 days of ethanol feeding or 22 days of phenobarbital administration did not increase GPAT activity. Feeding a high fat diet for 24 days increased GPAT activity per milligram of protein to an extent similar to that observed after chronic ethanol administration. When expressed per 100 g of body weight, however, the increase was much greater after ethanol. The significance of these findings in vivo has not been elucidated. Increased GPAT activity might contribute to the persistence of alcoholic fatty liver and the development of hyperlipemia.

Alcoholism↗