scholarly journals Regulation of ascorbic acid and of xylulose synthesis in rat-liver extracts. The effect of alloxan-diabetes on the glucuronic acid pathway

1965 ◽  
Vol 97 (2) ◽  
pp. 561-564 ◽  
Author(s):  
F Stirpe ◽  
M Comporti
Keyword(s):  
Ascorbic Acid ◽  
Insulin Therapy ◽  
Rat Liver ◽  
Alloxan Diabetes ◽  
Glucuronic Acid ◽  
Diabetic Rats ◽  
Acid Pathway

1. The synthesis of l-ascorbic acid and of l-xylulose from d-glucuronolactone, d-glucuronate, l-gulonate and l-gulonolactone has been studied with liver extracts from normal and alloxan-diabetic rats. 2. In diabetic animals the synthesis of ascorbic acid is impaired, and more from glucuronolactone and glucuronate than from gulonate and gulonolactone, whereas the formation of xylulose from gulonate and gulonolactone is enhanced. These changes are reversed by insulin therapy. 3. The activity of the NAD-linked gulonate dehydrogenase is enhanced during diabetes.

scholarly journals Contribution of Blood Phosphate Esters to the Blood Saccharoid Fraction of Rats with Alloxan-induced Diabetes or Treated with Insulin or Epinephrine

1974 ◽  
Vol 20 (9) ◽  
pp. 1165-1172 ◽  
Author(s):  
Zeenat- un-Nisa ◽  
M Ataur Rahman
Keyword(s):  
Ascorbic Acid ◽  
Uric Acid ◽  
Whole Blood ◽  
Glucuronic Acid ◽  
Weak Acid ◽  
Diabetic Rats ◽  
Phosphate Esters ◽  
Experimental Conditions ◽  
Dynamic Character ◽  
Reducing Substances

Abstract Nonglucose reducing substances in blood constitute the "saccharoid fraction," which increases both in hyperand hypoglycemia. The phosphate esters, including weak-acid phosphates and fructose-1,6-diphosphate, constitute 14 to 25% of the saccharoid fraction in whole blood, 2 to 9% in plasma, and 24 to 35% in erythrocytes of normal rats treated with insulin or epinephrine and of alloxan diabetic rats treated with insulin. Glutathione, glucuronic acid, ascorbic acid, uric acid, and creatinine (reported earlier) and the phosphate esters (reported here) altogether account for 75 to 100% of the saccharoid fraction under the experimental conditions used, except in the alloxan-diabetic rats, where on the fourth day of alloxan treatment a larger proportion was unaccounted for. The dynamic character of the saccharoid fraction is probably due to the evanescent nature of these phosphate esters.

Glucuronic acid pathway activity in adipose tissue

1964 ◽  
Vol 206 (1) ◽  
pp. 165-168 ◽  
Author(s):  
Albert I. Winegrad ◽  
Walter N. Shaw
Keyword(s):  
Growth Hormone ◽  
Adipose Tissue ◽  
Glucuronic Acid ◽  
Dilution Effect ◽  
Diabetic Rats ◽  
Relative Significance ◽  
Paired Samples ◽  
Acid Pathway

Paired samples of rat adipose tissue were incubated with glucose-U-C14 and the effect of unlabeled glucuronolactone on C14O2 production from glucose determined. Glucuronolactone significantly diluted C14O2 production in tissue from starved or alloxan diabetic rats, but not in tissue from normal fed animals. A dilution effect was observed in tissue from fed rats incubated with growth hormone; this effect was also observed with glucose-6-C14, but not with glucose-1-C14. In tissue from starved rats incubated with insulin, glucuronolactone did not dilute C14O2 production from glucose. A dilution effect was observed in tissue from normal rats after the injection of growth hormone, or barbital, which is known to stimulate this pathway in liver. The relative significance of the contribution of the glucuronic acid pathway to total CO2 production from glucose appears to be greater in tissue from starved or diabetic rats than in tissue from normal fed animals; it appears to be increased by growth hormone in vitro or in vivo, but in tissue from starved animals insulin appears to decrease it.

Changes in the Saccharoid Fraction in Rats with Alloxan-Induced Diabetes or Injected with Epinephrine

1971 ◽  
Vol 17 (9) ◽  
pp. 915-920 ◽  
Author(s):  
M Jafar Alam ◽  
M Ataur Rahman
Keyword(s):  
Ascorbic Acid ◽  
Uric Acid ◽  
Blood Glucose ◽  
Glucose Concentration ◽  
Glucuronic Acid ◽  
Blood Glucose Concentration ◽  
Diabetic Rats ◽  
Reducing Sugar ◽  
Sugar Phosphates ◽  
Reducing Substances

Abstract "Saccharoid fraction," defined as the nonglucose reducing substances in blood, increases both in hyperglycemia (blood glucose concentration exceeding 280 mg/dl) and hypoglycemia (blood sugar less than 65 mg/dl) in rats. This increase is not completely accounted for by glutathione, glucuronic acid, ascorbic acid, uric acid, and creatinine. Some of the constituents of saccharoid fraction seem to be insulin-sensitive. Alloxan not only produces diabetes in rats but also increases blood glucuronic acid, ascorbic acid, and uric acid. Estimated constituents of saccharoid fraction account for only 45% to 75% of the saccharoid fraction. The unaccounted-for saccharoid fraction shows changes similar to those in the accounted-for saccharoid fraction, in the diabetic rats, as was also the case after treatment with insulin of normal or diabetic animals. The fraction not accounted for by the estimated constituents may represent the reducing sugar phosphates present in the blood.

Effects of fasting and alloxan diabetes on albumin synthesis by perfused rat liver

1961 ◽  
Vol 201 (1) ◽  
pp. 55-57 ◽  
Author(s):  
Julian B. Marsh
Keyword(s):  
Cell Suspension ◽  
Rat Liver ◽  
Alloxan Diabetes ◽  
Diabetic Rats ◽  
Red Cell ◽  
Perfused Rat Liver ◽  
Albumin Synthesis ◽  
Plasma Albumin ◽  
Immunochemical Method

The net synthesis of plasma albumin by the rat liver perfused with a red cell suspension has been studied by a quantitative immunochemical method. Albumin synthesis was decreased by an average of 29% after a 24-hr fast in normal rats. It was also decreased by 41% in alloxan diabetic rats.

scholarly journals Activity and intracellular distribution of enzymes of ketone-body metabolism in rat liver

1968 ◽  
Vol 108 (3) ◽  
pp. 353-361 ◽  
Author(s):  
D. H. Williamson ◽  
Margaret W. Bates ◽  
H. A. Krebs
Keyword(s):  
Rat Liver ◽  
High Fat Diet ◽  
Ketone Body ◽  
Alloxan Diabetes ◽  
Normal Liver ◽  
Diabetic Rats ◽  
Intracellular Distribution ◽  
High Fat ◽  
Lyase Activity ◽  
Hydroxymethylglutaryl Coa Lyase

1. The activities of hydroxymethylglutaryl-CoA synthase and lyase in rat liver were found to be two- to 15-fold greater than those reported by other authors under similar conditions. 2. When expressed on the basis of body weight, no appreciable differences were found between the activities of hydroxymethylglutaryl-CoA synthase in whole homogenates of livers from normal and starved rats. The synthase activity increased by 70% and 140% in livers of alloxan-diabetic rats and rats fed on a high-fat diet respectively. 3. Hydroxymethylglutaryl-CoA lyase activity showed no significant increases in starvation or alloxan-diabetes, but a 40% increase was found in fat-fed rats. 4. Less than 12% of the activities of both enzymes were found in the cytoplasmic fraction of normal liver. The cytoplasmic activity doubled in alloxan-diabetes and starvation; on feeding with a high-fat diet the increase, though significant, was less marked. 6. The intracellular distribution of glutamate dehydrogenase indicated that the changes in the cytoplasmic activities observed were not due to leakage from the mitochondria. 7. Feeding with a normal or high-fat diet after 48hr. starvation caused within 24hr. a decrease in the cytoplasmic activity of hydroxymethylglutaryl-CoA synthase to values lower than those found in rats fed on a corresponding diet for a longer period of time. 8. Acetoacetyl-CoA deacylase activity in liver was about 20% of that of hydroxymethylglutaryl-CoA synthase and was primarily located in the cytoplasm. Starvation or alloxan-diabetes did not alter the acetoacetyl-CoA deacylase activity. 9. It is concluded that variations in the concentrations of enzymes involved in acetoacetate synthesis play no major role in the regulation of ketone-body formation in starvation and alloxan-diabetes. The changes in the cytoplasmic activities of hydroxymethylglutaryl-CoA synthase and lyase suggest that acetoacetate synthesis can occur in the cytoplasm. This may play a role in the disposal of surplus acetyl-CoA arising in the cytoplasm when lipogenesis is inhibited.

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