scholarly journals Rapid stimulation of the hepatic glycine-cleavage system in rats fed on a single high-protein meal

1992 ◽  
Vol 283 (2) ◽  
pp. 441-447 ◽  
Author(s):  
H S Ewart ◽  
M Jois ◽  
J T Brosnan
Keyword(s):  
High Protein Diet ◽  
High Protein ◽  
Rat Liver Mitochondria ◽  
Casein Diet ◽  
Glycine Cleavage System ◽  
Protein Meal ◽  
High Protein Meal ◽  
Protein Feeding ◽  
Glycine Cleavage ◽  
Stimulation Of

Glycine catabolism was studied in isolated rat liver mitochondria by measuring the release of 14CO2 from [1-14C]glycine. Mitochondria isolated from rats fed on a high-protein (60% casein) diet for 5 days showed an enhanced ability to catabolize glycine compared with mitochondria from rats fed on a normal-protein (15% casein) diet. Glycine catabolism was also stimulated in normal protein-fed rats if they ingested a single high-protein meal for 2 h before being killed, thus illustrating the rapid response of the glycine-cleavage system to protein intake. The stimulation of glycine catabolism in rats given a high-protein diet or meal was not evident if the mitochondria were incubated in the absence of P(i) (omitting ADP had no effect on the rate). Mitochondria from high-protein- and normal-protein-fed rats did not differ in their ability to accumulate glycine, a process which occurred far too rapidly to impose a limit on the rate of flux through the glycine-cleavage system. The stimulation of glycine catabolism by high-protein feeding was not associated with a change in mitochondrial matrix volume. Furthermore, mitochondria from rats fed on a high-protein meal maintained an enhanced ability to catabolize glycine compared with those from rats fed on a normal-protein meal when incubated in hypo-osmotic solutions of very low osmolarity. When mitochondria from high-protein- or normal-protein-fed rats were maximally activated by incubation in the presence of 0.25 microM-Ca2+, the rates of glycine catabolism were high, but similar, showing that the stimulation of glycine catabolism by high-protein feeding does not involve an increase in the total capacity of the system. These findings show that hepatic glycine catabolism is stimulated rapidly by high-protein feeding, a response that we suggest is involved in the disposal of the excess glycine in the diet.

Increased serum sulfate after protein loading in adult humans

1991 ◽  
Vol 69 (1) ◽  
pp. 25-27 ◽  
Author(s):  
David E. C. Cole ◽  
Anne M. Thurgood ◽  
Susan J. Whiting
Keyword(s):  
Sulfur Metabolism ◽  
High Protein ◽  
Protein Meal ◽  
Protein Loading ◽  
Low Protein ◽  
High Protein Meal ◽  
Protein Feeding ◽  
Sulfate Metabolism ◽  
Adult Volunteers ◽  
Serum Sulfate

To determine the effects of a protein loading on sulfate metabolism in humans, we monitored serum sulfate concentrations in 12 fasting adult volunteers fed a high-protein meal of egg white and an isocaloric low-protein meal. With each subject serving as his or her own control, we found that mean serum sulfate rose only slightly with the low-protein meal but was significantly higher with high-protein loading at 3 and 3.5 h. The median of the peak sulfate concentration was 57% greater than baseline with the high-protein meal versus 11% with no loading. Since changes in serum sulfate have been shown to influence the rate of sulfation for a variety of different acceptor molecules, these observations indicate a means by which protein feeding may simultaneously influence diverse metabolic pathways.Key words: serum sulfate, protein intake, sulfur metabolism, human dietary studies.

scholarly journals Consumption of a High-Protein Meal Replacement Leads to Higher Fat Oxidation, Suppression of Hunger, and Improved Metabolic Profile After an Exercise Session

Nutrients ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 155
Author(s):  
Camila L. P. Oliveira ◽  
Normand G. Boulé ◽  
Aloys Berg ◽  
Arya M. Sharma ◽  
Sarah A. Elliott ◽  
...  
Keyword(s):  
Metabolic Profile ◽  
Fat Oxidation ◽  
High Protein ◽  
Whole Body ◽  
Moderate Intensity ◽  
Exercise Session ◽  
Meal Replacement ◽  
Protein Meal ◽  
High Protein Meal ◽  
The Impact

The aim of this study was to compare the impact of a high-protein meal replacement (HP-MR) versus a control (CON) breakfast on exercise metabolism. In this acute, randomized controlled, cross-over study, participants were allocated into two isocaloric arms: (a) HP-MR: 30% carbohydrate, 43% protein, and 27% fat; (b) CON: 55% carbohydrate, 15% protein, and 30% fat. Following breakfast, participants performed a moderate-intensity aerobic exercise while inside a whole-body calorimetry unit. Energy expenditure, macronutrient oxidation, appetite sensations, and metabolic blood markers were assessed. Forty-three healthy, normal-weight adults (24 males) participated. Compared to the CON breakfast, the HP-MR produced higher fat oxidation (1.07 ± 0.33 g/session; p = 0.003) and lower carbohydrate oxidation (−2.32 ± 0.98 g/session; p = 0.023) and respiratory exchange ratio (−0.01 ± 0.00; p = 0.003) during exercise. After exercise, increases in hunger were lower during the HP-MR condition. Changes in blood markers from the fasting state to post-exercise during the HP-MR condition were greater for insulin, peptide tyrosine-tyrosine, and glucagon-like peptide 1, and lower for low-density lipoprotein cholesterol, triglyceride, and glycerol. Our primary findings were that an HP-MR produced higher fat oxidation during the exercise session, suppression of hunger, and improved metabolic profile after it.

scholarly journals Adaptive changes in the capacity of systems used for the synthesis of citrulline in rat liver mitochondria in response to high- and low-protein diets

1974 ◽  
Vol 142 (2) ◽  
pp. 359-364 ◽  
Author(s):  
J. D. McGivan ◽  
Norah M. Bradford ◽  
J. B. Chappell
Keyword(s):  
Nitrogen Source ◽  
High Protein Diet ◽  
Liver Mitochondria ◽  
High Protein ◽  
Protein Diet ◽  
Rat Liver Mitochondria ◽  
Standard Diet ◽  
Adaptive Changes ◽  
Low Protein ◽  
Citrulline Synthesis

1. Citrulline synthesis was measured in mitochondria from rats fed on a standard diet, a high-protein diet, or on glucose. 2. With NH4Cl as the nitrogen source the rate of citrulline synthesis was higher in mitochondria from rats fed on a high-protein diet than in those from rats fed on a standard diet. When rats were fed solely on glucose the rate of synthesis of citrulline from NH4Cl was very low. 3. With glutamate as the nitrogen source the relative rates of citrulline synthesis were much lower than when NH4Cl was present, but similar adaptive changes occurred. 4. The activity of the mitochondrial glutamate-transporting system increased two to three times on feeding rats on a high-protein diet, but the Km for glutamate was unchanged. 5. Adaptive changes in certain intramitochondrial enzymes were also measured. 6. The results were interpreted to indicate that when an excess of substrate was present, citrulline synthesis from NH4Cl was rate-limited by the intramitochondrial concentration of N-acetyl-glutamate, but citrulline synthesis from glutamate was rate-limited primarily by the activity of the glutamate-transporting system.

Effect of a meal containing protein on lithium clearance and plasma immunoreactive atrial natriuretic peptide in man

1988 ◽  
Vol 75 (2) ◽  
pp. 151-157 ◽  
Author(s):  
L. R. Solomon ◽  
J. C. Atherton ◽  
H. Bobinski ◽  
S. L. Cottam ◽  
C. Gray ◽  
...  
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Protein Content ◽  
Natriuretic Peptide ◽  
Proximal Tubules ◽  
High Protein ◽  
Lithium Clearance ◽  
Protein Meal ◽  
Low Protein ◽  
High Protein Meal ◽  
Atrial Natriuretic

1. The effect of meals with a high and low protein content and of the fasting state on renal function and plasma atrial natriuretic peptide was studied in water-loaded normal volunteers. 2. Creatinine clearance increased after the high protein meal, but did not change after the low protein meal or while fasting. Observations of similar increases in urine sodium and potassium excretion and a transient decrease in urine flow after both meals suggest that the protein content of the meal is not an important contributory factor in these responses to feeding. 3. Absolute delivery of sodium and water out of the proximal tubules (assessed by the lithium clearance method) was higher after both meals than while fasting; fractional lithium clearance was higher after the low protein meal than the high protein meal and while fasting. Absolute reabsorption from proximal tubules was increased after only the high protein meal. 4. A transient decrease in the fraction of water delivered to distal nephron segments that appeared in the urine (fractional distal water excretion) was observed after both meals. Fractional distal sodium excretion and absolute distal sodium and water reabsorption increased after both meals. 5. Since plasma atrial natriuretic peptide either decreased (high protein meal) or remained unchanged (low protein meal and fasting), it is unlikely that this hormone is involved in the hyperfiltration after the high protein meal and the natriuresis after both high and low protein meals.

Time Course of Enzyme Adaptation. III. Periodic and Nonperiodic Responses of Rat Liver Enzyme Activities to Diets in Meal-Fed Rats

1971 ◽  
Vol 49 (1) ◽  
pp. 108-118 ◽  
Author(s):  
B. Szepesi ◽  
R. A. Freedland
Keyword(s):  
Pyruvate Kinase ◽  
High Protein Diet ◽  
Periodic Variation ◽  
Maximum Activity ◽  
High Protein ◽  
Protein Diet ◽  
Liver Protein ◽  
Casein Diet ◽  
Phosphohexose Isomerase ◽  
Glucose 6 Phosphate Dehydrogenase

Enzymes associated with carbohydrate and amino acid metabolism as well as other liver constituents were studied in rats meal-fed, daily for 60 min, diets consisting of corn oil, salt, and vitamins plus 75% carbohydrate and 15% casein or a 90% casein diet. Relative liver size and the levels of liver glycogen and total and soluble liver protein were subject to periodic variation after the ingestion of a meal. They reached maximums about 6–12 h after the meal and then declined. In the rats fed the 90% casein diet the onset of increases was delayed after the first meal.The activity of glucose-6-phosphatase was increased by a fructose diet and the high-protein diet, but no periodicity was observed. The activities of fructose-1, 6-diphosphatase, dihydroxyacetone kinase, and malic enzyme were not subject to periodic variation, and these enzymes were not increased by the fructose or high-protein diets. Serine dehydrase activity was increased by the high-protein diet, but the question of periodicity cannot be resolved with the available data.The tyrosine–α-ketoglutarate transaminase activity in rats fed a 75% glucose – 15% casein diet was subject to periodic variation. Maximum activity occurred just before feeding, and minimum activity 12 h after feeding. In the rats fed the 90% casein diet the activity of the enzyme was considerably increased, and was already maximum 3 h after the meal. The activity then decreased to a relatively high minimum 12 h after the meal, at which time it began to increase again.The activities of pyruvate kinase, glucose-6-phosphate dehydrogenase, and phosphohexose isomerase were all subject to periodicity in the glucose-fed rats. In the rats fed the high-protein diet, there was a periodic response in activity of both pyruvate kinase and glucose-6-phosphate dehydrogenase after the first meal; but enzyme activity remained minimum after the second meal. Glucose-6-phosphate dehydrogenase and phosphohexose isomerase activities were increased after three meals of the fructose diet, and were higher than in glucose-fed rats even 24 h after a meal. Maximum activity of these three enzymes occurred 12 h after the meal. There was only small periodicity in the activity of glutamic–pyruvic transaminase. The activity of this enzyme was increased by the high-protein diet and also by the high-fructose diet, although the latter effect was only temporary. The possible importance of certain types of adaptations in meal-fed rats was discussed in connection with physiological requirements.

scholarly journals Effect of a high protein meal on the bioavailability of verapamil.

1986 ◽  
Vol 21 (3) ◽  
pp. 337-338 ◽  
Author(s):  
BG Woodcock ◽  
N. Kraemer ◽  
N. Rietbrock
Keyword(s):  
High Protein ◽  
Protein Meal ◽  
High Protein Meal
Sign in / Sign up

Export Citation Format

Share Document