scholarly journals Control in vivo of rat liver phosphofructokinase by glucagon and nutritional changes

1980 ◽  
Vol 186 (3) ◽  
pp. 953-957 ◽  
Author(s):  
A Nieto ◽  
J G Castaño
Keyword(s):  
Enzyme Activity ◽  
Pyruvate Kinase ◽  
High Protein Diet ◽  
High Carbohydrate Diet ◽  
Physiological Changes ◽  
Carbohydrate Diet ◽  
High Carbohydrate ◽  
Dietary Condition ◽  
Phosphofructokinase Activity

Glucagon (250 microgram/kg body wt.) intravenously injected into normal fed rats produces within 5 min a marked inactivation of liver phosphofructokinase, only observed when the enzyme activity is measured at subsaturating concentrations of fructose 6-phosphate. Since half-maximal inactivation is observed at a dose of glucagon of 0.32 microgram/body wt., a dose within the range of the physiological concentrations of the hormone, the inactivation of phosphofructokinase can occur in vivo in response to physiological changes in the concentration of glucagon. In gluconeogenic conditions (starved rats or high-protein-diet-fed rats), there is a marked inactivation of liver phosphofructokinase at subsaturating concentrations of fructose 6-phosphate similar to that found in normal fed rats after glucagon treatment. In these gluconeogenic conditions a 50% decrease in the Vmax. of the enzyme is also observed. No significant changes in phosphofructokinase activity either at subsaturating concentrations of fructose 6-phosphate or in the Vmax. of the enzyme are observed when rats are fed on a high-carbohydrate diet. In the last dietary condition, glucagon treatment produces similar effects to that described in the normal fed rats. Similar results have been obtained in the above condtions for pyruvate kinase L activity when measured at subsaturating concentrations of phosphoenolpyruvate.

Analysis of hormonal–dietary interactions and the role of gluconeogenesis in the regulation of tyrosine aminotransferase in rats

1969 ◽  
Vol 47 (11) ◽  
pp. 1053-1061 ◽  
Author(s):  
C. Mavrides ◽  
E. A. Lane
Keyword(s):  
Enzyme Activity ◽  
High Protein Diet ◽  
Tyrosine Aminotransferase ◽  
High Carbohydrate Diet ◽  
Protein Diet ◽  
Carbohydrate Diet ◽  
Hormonal Stimulation ◽  
High Carbohydrate ◽  
Hormonal Effect ◽  
Stimulation Of

The extent of stimulation of rat liver tyrosine aminotransferase by Cortisol and glucagon is inversely proportional to the basal activity of the enzyme in adrenalectomized and hypophysectomized rats. The basal activity is low in animals fed a high-carbohydrate diet leading to high hormonal stimulation of the enzyme, and high in animals fed a high-protein diet leading to minimal or no hormonal stimulation. The dietary modifications of the hormonal effects have been analyzed into two independent processes. Upon short-term starvation, the enzyme activity declines rapidly in animals previously fed a high-protein diet but rises rapidly in animals previously fed a high-carbohydrate diet. Superimposing a positive (hormonal) effect on these two diametrically opposite processes results in profound modification of the hormonal effect on the enzyme activity. The experiments further suggest that the regulation of tyrosine aminotransferase is coupled with gluconeogenic activity per se rather than with a primary hormonal action at the genetic level.

scholarly journals Biochemical aspects of malabsorption in marasmus: effect of dietary rehabilitation

1985 ◽  
Vol 54 (3) ◽  
pp. 567-575 ◽  
Author(s):  
H. C. Mehta ◽  
A. S. Saini ◽  
Harjit Singh ◽  
P. S. Dhatt
Keyword(s):  
Total Energy ◽  
High Fat Diet ◽  
High Protein Diet ◽  
High Carbohydrate Diet ◽  
High Protein ◽  
Protein Diet ◽  
Duodenal Juice ◽  
High Fat ◽  
Carbohydrate Diet ◽  
High Carbohydrate

1. Sixty marasmic children were investigated for the absorption of xylose, proteins and fats. Their duodenal juice samples were also analysed for bile salts and microflora.2. The marasmic children were then studied in three groups of twenty by allocating them to three different dietary schedules: a high-protein diet (30% of the total energy from protein), a high-fat diet (40% of the total energy from fat) and a high-carbohydrate diet (70% of the total energy from carbohydrate) for 2 weeks and the previous measurements repeated.3. Whereas the high-fat diet resulted in improved fat absorption, along with an increase in total and conjugated bile acids, and the high-carbohydrate diet led to improved xylose absorption, the diet rich in protein resulted in an improvement in the absorption of all three dietary ingredients. It appears that a high-protein diet improves the overall absorption process by improving the intestinal environment as a whole, while high-carbohydrate and high-fat diets bring about adaptive changes related to the respective absorptive processes.

Stearic Acid Supplementation in High Protein to Carbohydrate (P:C) Ratio Diet Improves Physiological and Mitochondrial Functions of Drosophila melanogaster parkin Null Mutants

2017 ◽  
Vol 74 (10) ◽  
pp. 1564-1572 ◽  
Author(s):  
Rijan Bajracharya ◽  
Sonia Bustamante ◽  
John William O Ballard
Keyword(s):  
Fatty Acids ◽  
Stearic Acid ◽  
High Protein Diet ◽  
High Carbohydrate Diet ◽  
High Protein ◽  
Protein Diet ◽  
Carbohydrate Diet ◽  
High Carbohydrate ◽  
Mitochondrial Functions ◽  
And Mitochondrial Functions

Abstract Optimizing dietary macronutrients benefits the prevention and management of many human diseases but there is conflicting dietary advice for Parkinson’s disease (PD), and no single strategy is universally recommended. Recently, it was shown that dietary stearic acid (C18:0) improves survival and mitochondrial functions in the parkin null Drosophila model of PD. Here, we incorporate stearic acid into high protein and high carbohydrate diets and study survival, climbing ability, mitochondrial membrane potential, respiration, basal reactive oxygen species, and conduct lipidomics assays. We observed that parkin null flies showed improvement in all assays tested when stearic acid was added to the high protein diet but not to the high carbohydrate diet. When lipid proportion was examined, we observed higher levels in flies fed the high protein diet with stearic acid diet and the high carbohydrate diet. Unexpectedly, free levels of fatty acids exhibited opposite trend. Combined, these data suggest that dietary Protein: Carbohydrate ratio and stearic acid influences levels of bound fatty acids. The mechanisms that influence free and bound fatty-acid levels remain to be explored, but one possible explanation is that breakdown products can bind to membranes and improve the mitochondrial functions of parkin null flies.

Effect of a High Carbohydrate Diet on Insulin Binding to Adipocytes and on Insulin Action in vivo in Man

Diabetes ◽  
1979 ◽  
Vol 28 (8) ◽  
pp. 731-745 ◽  
Author(s):  
O. G. Kolterman ◽  
M. Greenfield ◽  
G. M. Reaven ◽  
M. Saekow ◽  
J. M. Olefsky
Keyword(s):  
Insulin Action ◽  
Insulin Binding ◽  
High Carbohydrate Diet ◽  
Carbohydrate Diet ◽  
High Carbohydrate

Hypocaloric high-protein diet improves glucose oxidation and spares lean body mass: Comparison to hypocaloric high-carbohydrate diet

Metabolism ◽  
1994 ◽  
Vol 43 (12) ◽  
pp. 1481-1487 ◽  
Author(s):  
P.M. Piatti ◽  
L.D. Monti ◽  
Fulvio Magni ◽  
Isabella Fermo ◽  
L. Baruffaldi ◽  
...  
Keyword(s):  
Lean Body Mass ◽  
Body Mass ◽  
Glucose Oxidation ◽  
High Protein Diet ◽  
High Carbohydrate Diet ◽  
High Protein ◽  
Protein Diet ◽  
Carbohydrate Diet ◽  
High Carbohydrate ◽  
Mass Comparison

Effect of a high carbohydrate diet on insulin binding to adipocytes and on insulin action in vivo in man

Diabetes ◽  
1979 ◽  
Vol 28 (8) ◽  
pp. 731-736 ◽  
Author(s):  
O. G. Kolterman ◽  
M. Greenfield ◽  
G. M. Reaven ◽  
M. Saekow ◽  
J. M. Olefsky
Keyword(s):  
Insulin Action ◽  
Insulin Binding ◽  
High Carbohydrate Diet ◽  
Carbohydrate Diet ◽  
High Carbohydrate

scholarly journals The effect of dietary composition and of insulin on gluconeogenesis in rainbow trout (Salmo gairdneri)

1977 ◽  
Vol 38 (3) ◽  
pp. 385-395 ◽  
Author(s):  
C. B. Cowey ◽  
M. De La Higuera ◽  
J. W. Adron
Keyword(s):  
Rainbow Trout ◽  
High Protein Diet ◽  
High Carbohydrate Diet ◽  
High Protein ◽  
Protein Diet ◽  
Salmo Gairdneri ◽  
Carbohydrate Diet ◽  
Commercial Diet ◽  
High Carbohydrate ◽  
Gluconeogenesis From Alanine

1. The activities at 15° of three gluconeogenic enzymes, d-fructose-1,6-diphosphate, 1-phosphohydrolase (EC 3.1.3.11), pyruvate carboxylase (EC 6.4.1.1) and phosphoenolpyruvate carboxykinase (4.1.1.32), were determined in liver, kidney, gill and muscle of rainbow trout (Salmo gairdneri) given a commercial diet. The results indicated that liver and kidney are the main sites of gluconeogenesis.2. Glucose formation from pyruvate was approximately 6 μmol/h per g wet weight at 15° in liver slices of trout given a commercial diet.3. Glucose diffusion space in trout was measured by the dilution principle after intravascular injection of a trace dose of [U-14C]glucose. Glucose space was found to be 13.7% of the body-weight. Gluconeogenesis in vivo amounted to approximately 45 μmol/kg body-weight per h.4. Intraperitoneally injected [U-14C]alanine was quickly converted to glucose. Maximal incorporation of alanine into glucose occurred 6 h after alanine administration.5. Rainbow trout given a high-protein diet gained in weight significantly during a 4-week period. Those given a high-carbohydrate diet did not make a significant weight gain over the same period. Gluconeogenesis from alanine was markedly reduced in fish given the high-carbohydrate diet. There was no significant difference in gluconeogenesis from alanine in fish given a high-protein diet and fish which were fasted for 21 d.6. Gluconeogenesis from alanine in trout was suppressed by intravenous injection of insulin. This effect was found both in trout given a high-protein diet and in fasted trout.

scholarly journals Studies on the biosynthesis of hepatic pyruvate kinase and its correlation with enhanced hepatic lipogenesis in meal-trained rats

1979 ◽  
Vol 182 (2) ◽  
pp. 383-397 ◽  
Author(s):  
T J Hopkirk ◽  
D P Bloxham
Keyword(s):  
Fatty Acid ◽  
Pyruvate Kinase ◽  
Fatty Acid Synthesis ◽  
Specific Activity ◽  
Acid Synthesis ◽  
High Carbohydrate Diet ◽  
Hill Coefficient ◽  
Carbohydrate Diet ◽  
High Carbohydrate ◽  
Maximum Activation

Metabolic and enzymic changes were measured in meal-trained rats fed on high-carbohydrate diet. Rates of hepatic fatty acid synthesis are probably greater than rates of gluconeogenesis throughout the 24 h day provided that animals are fed. The daily enhancement of fatty acid synthesis on meal feeding coincided with the maximum activation of hepatic pyruvate kinase. Maximum activation of this enzyme was reflected in increased total catalytic activity (Vmax.), increased activity at 0.5 MM-phosphoenolpyruvate (V0.5), decreased Vmax./V0.5 ratio and a decrease in co-operativity of phosphoenolpyruvate binding as measured by the Hill coefficient (h). The latter changes are consistent with a decrease in enzyme phosphorylation during activation of the enzyme. To estimate changes in enzyme protein, quantitative enzyme precipitation with rabbit antisera was used. Giving a high-carbohydrate diet to meal-trained animals induced enzyme synthesis within a few hours. Adaptations in diet that enhanced fatty acid synthesis (chow to high carbohydrate; starved to high carbohydrate) led to an increased steady-state concentration of pyruvate kinase protein. An approximate estimate of the half-life of hepatic pyruvate kinase was 56 h. Whenever pyruvate kinase specific activity was measured in liver tissue extracts it was always considerably less (20–100 mumol/min per mg of protein, depending on dietary status) than the specific activity of pure pyruvate kinase (200 mumol/min per mg of protein). Antigenically active, catalytically inactive protein was removed during enzyme purification from cytosol at the stage of (NH4)2SO4 fractionation. The fraction precipitated by 30–45%-satd. (NH4)2SO4 was enzymically active, antigenically reacting protein was identified in the remaining (NH4)2SO4 fractions (0–30%- and 45–85%-satd.) and this contained no enzyme activity. These may correspond to inactive proteolytic fragments of pyruvate kinase. The rate-determining step in adjusting enzyme concentration seems to be proteolysis.

Diets alter jejunal morphology and brush border membrane composition in streptozotocin-diabetic rats

1987 ◽  
Vol 65 (2) ◽  
pp. 210-218 ◽  
Author(s):  
M. Keelan ◽  
K. Walker ◽  
R. Rajotte ◽  
T. Clandinin ◽  
A. B. R. Thomson
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Essential Fatty Acids ◽  
High Protein Diet ◽  
Diabetic Rats ◽  
High Carbohydrate Diet ◽  
Protein Diet ◽  
Phospholipid Content ◽  
Carbohydrate Diet ◽  
High Carbohydrate

Previous studies have demonstrated enhanced active and passive uptake of many nutrients in animals with experimental diabetes. These changes in absorption cannot be explained by differences in intestinal morphology, although the brush border membrance (BBM) phospholipids do change in diabetes. Manipulation of diet produces alterations in intestinal uptake of lipids and glucose. This study was undertaken to determine the effect of diet and diabetes on jejunal morphology and BBM lipid composition. Rats were rendered hyperglycemic with streptozotocin and were fed for 2 weeks on a diet that was high or low in carbohydrate, essential fatty acids, cholesterol, or protein. In both control and diabetic rats, these diets produced changes in villus height and BBM sucrase and alkaline phosphatase activities. In both control and diabetic rats, BBM phospholipids were unaffected by changes in the dietary content of essential fatty acids, cholesterol, or protein, but total BBM phospholipid content was reduced in animals fed low as compared with high carbohydrate diet. Total BBM phospholipid content was higher in diabetic than in control animals fed the low protein diet, whereas BBM phospholipid content was lower in diabetic than in control animals fed the high carbohydrate diet, and was even lower in diabetic animals fed the low as compared with the high carbohydrate diet. These changes in total phospholipids were due to alterations in the BBM content of phospholipids containing choline. In control animals, BBM cholesterol was higher in rats fed the low as compared with the high cholesterol diet, or the low as compared with the high protein diet. In diabetic rats, BBM cholesterol was higher than in animals fed the low as compared with the high essential fatty acid or high protein diet. BBM cholesterol was higher in diabetic than in control rats only when fed the low essential fatty acid diet. The results show that (i) diabetes and dietary manipulation produce changes in villus morphology, BBM enzymes, and lipids, but there is no apparent relationship between alterations in the various parameters measured; and (ii) diet and diabetes may alter lipid uptake as a result of qualitative and quantitative changes in the choline phospholipids in the intestinal brush border membrane.

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