Uptake and metabolism of amino acids by the dog liver perfused in situ

1962 ◽  
Vol 202 (3) ◽  
pp. 407-414 ◽  
Author(s):  
Rapier H. McMenamy ◽  
William C. Shoemaker ◽  
Jonas E. Richmond ◽  
David Elwyn
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Sharp Rise ◽  
Dog Blood ◽  
Dog Liver ◽  
Amino Acid Concentrations ◽  
Uptake And Metabolism

Dog livers were perfused in situ for periods up to 6 hr with dog blood recycled through a pump-oxygenator. An amino acid mixture was administered for 90 min. Concentrations of amino acids were determined at intervals of 30 min or more. Rates of uptake and metabolism were calculated. After the start of perfusion, there is a fall in most plasma amino acid concentrations and a reciprocal rise in liver amino acids. Addition of amino acids causes a sharp rise in plasma amino acids. There is a rapid uptake of most of the amino acids by liver, although the concentrations of amino acids in liver fail to rise appreciably. Notable exceptions are valine, leucine, and isoleucine. Uptake of amino acids stimulates: a) an increase in the rate of synthesis of urea which ultimately accounts for 90% of the metabolized amino acids; b) a net synthesis of ornithine; and c) net noncatabolic metabolism of amino acids which may in part be protein synthesis. The results support the view that the liver temporarily stores a part of ingested amino acids as proteins, and subsequently makes them available to other organs.

Flux and turnover rates of glycine in the dog liver perfused in situ

1962 ◽  
Vol 202 (3) ◽  
pp. 415-419
Author(s):  
David Elwyn ◽  
Jonas E. Richmond ◽  
Rapier H. McMenamy ◽  
William C. Shoemaker
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Turnover Rate ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Turnover Rates ◽  
Net Flux ◽  
Specific Activities ◽  
Dog Liver

Distribution of added glycine-1-C14 in the perfused dog liver was studied. Concentrations and specific activities of glycine in liver and plasma were measured as a function of time. Calculated values for glycine fluxes between plasma and liver were for influx, 10 to 150, efflux, 10 to 90, and for net influx into liver, –10 to 80 µmole/min/kg liver. Administration of an amino acid mixture containing unlabeled glycine increased the rates of influx, efflux and net flux of glycine into the liver, as well as the concentration of glycine in plasma. The turnover rate of glycine in liver was found to be of the order of 400 µmole/min/kg liver. The specific activities of other amino acids, glucose, and glycogen were measured.

Amino Acid Concentrations in Portal Venous Plasma during Absorption from the Small Intestine of the Guinea Pig of an Amino Acid Mixture Simulating Casein and a Partial Enzymic Hydrolysate of Casein

1977 ◽  
Vol 52 (3) ◽  
pp. 259-267
Author(s):  
M. H. Sleisenger ◽  
D. Pelling ◽  
D. Burston ◽  
D. M. Matthews
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Guinea Pig ◽  
Preliminary Investigation ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Analytical Technique ◽  
Amino Acid Mixtures ◽  
Amino Acid Concentrations ◽  
Venous Plasma

1. The characteristics of absorption of individual amino acids from amino acid mixtures simulating casein and from enzymic hydrolysates of casein containing oligopeptides as well as free amino acids are known to be different. The differences, which are attributable to mucosal uptake of small peptides, involve more rapid absorption from the enzymic hydrolysates of certain amino acids which are relatively slowly absorbed from the amino acid mixtures. This could lead to more effective utilization of amino acids from the enzymic hydrolysates than from the amino acid mixtures. 2. To obtain further information bearing on this hypothesis, we have used a recently developed technique for portal cannulation in the guinea pig to make a preliminary investigation of amino acid concentrations in the portal venous plasma at intervals after the infusion into the duodenum of equivalent amounts of (a) an amino acid mixture simulating casein and (b) a partial enzymic (papain followed by kidney peptidases) hydrolysate of casein, the two preparations being infused in separate experiments. 3. For some amino acids, such as leucine, isoleucine, valine, phenylalanine and lysine, the curves after the enzymic hydrolysate were fairly similar to the corresponding curves after the amino acid mixture, though usually slightly lower. With other amino acids, the curves after the enzymic hydrolysate were very much lower than the corresponding curves after the amino acid mixture. With serine, glutamine, proline and glycine this discrepancy was particularly great. 4. The results cannot yet be fully explained, but their main features are explicable by the hypothesis that the lower amino acid concentrations in portal plasma after the enzymic hydrolysate are the result of entry of amino acids into the portal blood in peptide form, in which they would not be detectable by the analytical technique employed, and possibly also of more rapid clearance of amino acids from the blood during absorption of this preparation.

scholarly journals Effect of co-ingestion of amino acids with rice on glycaemic and insulinaemic response

2015 ◽  
Vol 114 (11) ◽  
pp. 1845-1851 ◽  
Author(s):  
Yean Yean Soong ◽  
Joseph Lim ◽  
Lijuan Sun ◽  
Christiani Jeyakumar Henry
Keyword(s):  
Amino Acids ◽  
Blood Glucose ◽  
Amino Acid ◽  
Glycaemic Index ◽  
Amino Acid Mixture ◽  
Postprandial Blood Glucose ◽  
Acid Mixture ◽  
White Rice ◽  
Amino Acid Mixtures

AbstractConsumption of high glycaemic index (GI) and glycaemic response (GR) food such as white rice has been implicated in the development of type 2 diabetes. Previous studies have reported the ability of individual amino acids to reduce GR of carbohydrate-rich foods. Because of the bitter flavour of amino acids, they have rarely been used to reduce GR. We now report the use of a palatable, preformed amino acid mixture in the form of essence of chicken. In all, sixteen healthy male Chinese were served 68 or 136 ml amino acid mixture together with rice, or 15 or 30 min before consumption of white rice. Postprandial blood glucose and plasma insulin concentrations were measured at fasting and every 15 min after consumption of the meal until 60 min after the consumption of the white rice. Subsequent blood samples were taken at 30-min intervals until 210 min. The co-ingestion of 68 ml of amino acid mixture with white rice produced the best results in reducing the peak blood glucose and GR of white rice without increasing the insulinaemic response. It is postulated that amino acid mixtures prime β-cell insulin secretion and peripheral tissue uptake of glucose. The use of ready-to-drink amino acid mixtures may be a useful strategy for lowering the high-GI rice diets consumed in Asia.

Liver extract and its free amino acids equally stimulate gastric acid secretion

1980 ◽  
Vol 239 (6) ◽  
pp. G493-G496 ◽  
Author(s):  
E. J. Feldman ◽  
M. I. Grossman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Free Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Liver Extract ◽  
Amino Acid Mixture ◽  
Acid Mixture

Using intragastric titration in dogs with gastric fistulas, dose-response studies were carried out with liver extract and with a mixture of amino acids that matched the free amino acids found in liver extract. All solutions were adjusted to pH 7.0 and osmolality to 290 mosmol x kg-1. Doses are expressed as the sum of the concentrations of all free amino acids. At each dose studied (free amino acid concentration: 2.8, 5.6, 11, 23, and 45 mM), acid secretion in response to the free amino acid mixture was not significantly different from that of liver extract. The peak response to both liver extract and the free amino acid mixture occurred with the 23-mM dose and represented about 60% of the maximal response to histamine. The serum concentrations of gastrin after liver extract and the amino acid mixture were not significantly different. It is concluded that in dogs with gastric fistula, gastric acid secretion and release of gastrin were not significantly different in response to liver extract and to a mixture of amino acids that simulated the free amino acid content of liver extract.

An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein

1997 ◽  
Vol 273 (1) ◽  
pp. E122-E129 ◽  
Author(s):  
G. Biolo ◽  
K. D. Tipton ◽  
S. Klein ◽  
R. R. Wolfe
Keyword(s):  
Amino Acids ◽  
Blood Flow ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Protein Kinetics ◽  
Amino Acid Infusion

Six normal untrained men were studied during the intravenous infusion of a balanced amino acid mixture (approximately 0.15 g.kg-1.h-1 for 3 h) at rest and after a leg resistance exercise routine to test the influence of exercise on the regulation of muscle protein kinetics by hyperaminoacidemia. Leg muscle protein kinetics and transport of selected amino acids (alanine, phenylalanine, leucine, and lysine) were isotopically determined using a model based on arteriovenous blood samples and muscle biopsy. The intravenous amino acid infusion resulted in comparable increases in arterial amino acid concentrations at rest and after exercise, whereas leg blood flow was 64 +/- 5% greater after exercise than at rest. During hyperaminoacidemia, the increases in amino acid transport above basal were 30-100% greater after exercise than at rest. Increases in muscle protein synthesis were also greater after exercise than at rest (291 +/- 42% vs. 141 +/- 45%). Muscle protein breakdown was not significantly affected by hyperminoacidemia either at rest or after exercise. We conclude that the stimulatory effect of exogenous amino acids on muscle protein synthesis is enhanced by prior exercise, perhaps in part because of enhanced blood flow. Our results imply that protein intake immediately after exercise may be more anabolic than when ingested at some later time.

TrophAmine

PEDIATRICS ◽  
1988 ◽  
Vol 82 (3) ◽  
pp. 389-390
Author(s):  
WILLIAM C. HEIRD
Keyword(s):  
Birth Weight ◽  
Amino Acid ◽  
Low Birth Weight ◽  
Controlled Trial ◽  
Nitrogen Retention ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Concerted Effort ◽  
Low Birth Weight Infants ◽  
Amino Acid Concentrations

In Reply.— The purpose of the study reported in the paper1 to which Zlotkin refers was to evaluate the efficacy of a new parenteral amino acid mixture (ie, TrophAmine) with respect to maintaining "normal" plasma amino acid concentrations and promoting nitrogen retention in low birth weight infants. Because the study was not a controlled trial in which this amino acid mixture was compared with another mixture, a concerted effort was made to avoid drawing conclusions or stating claims regarding the efficacy of this amino acid mixture relative to other mixtures.

Amino Acids in Premature Infants

PEDIATRICS ◽  
1988 ◽  
Vol 82 (4) ◽  
pp. 680-680
Author(s):  
NIELS C. R. RÄIHÄ
Keyword(s):  
Amino Acids ◽  
Birth Weight ◽  
Amino Acid ◽  
Parenteral Nutrition ◽  
Premature Infants ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Metabolic Capacity ◽  
Low Birth Weight Infants ◽  
Term Infants

To the Editor.— In a recent paper in Pediatrics, Heird et al1 reported their evaluation of the use of a new amino acid mixture for parenteral nutrition in low birth weight infants. On the basis of their results the authors made the following statement: "These observations refute the concept that the metabolic capacity of LBW infants for amino acids is limited in comparison to that of term infants, older infants, and chi1dren."1(p49) Such a conclusion is not justified on the basis of the presented data.

Effects of amino acids and gastric inhibitory polypeptide on insulin release in dogs

1982 ◽  
Vol 242 (1) ◽  
pp. E53-E58
Author(s):  
J. G. Yovos ◽  
T. M. O'Dorisio ◽  
T. N. Pappas ◽  
S. Cataland ◽  
F. B. Thomas ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Insulin Release ◽  
Insulin Response ◽  
Gastric Inhibitory Polypeptide ◽  
Amino Acid Mixture ◽  
Group Iv ◽  
Acid Mixture ◽  
Group Iii ◽  
Group I

Insulin release following intravenous administration of an amino acid solution with and without a simultaneous infusion of varying amounts of porcine gastric inhibitory polypeptide (GIP) was studied in dogs. Group I received a 10-amino acid mixture (300 mosmol/kg iv) at 16.6 ml/min for 1 h; group II, amino acid mixture plus 0.5 micrograms.kg-1.h-1 porcine GIP; group III, amino acid mixture plus 1.0 micrograms.kg-1.h-1 of GIP; group IV (a and b) received either 0.5 or 1.0 micrograms.kg-1.h-1 of GIP alone. Compared to group I, groups II and III had a greater insulin response during the first 30 min of the infusion. Group] IV (a and b) showed no insulin release. Glucose concentrations showed no significant change in all groups. From these results, it is concluded that insulin release after intravenous infusion of an amino acid mixture plus GIP is greater than after amino acids or GIP alone. It appears that this effect is more pronounced in the early phase of insulin release.

Chromatographic Separation of Free Amino Acids in Table Sirups

1971 ◽  
Vol 54 (1) ◽  
pp. 61-65
Author(s):  
Arthur Russell Johnson ◽  
Richard L Corliss ◽  
Enrique Fernandez-Flores
Keyword(s):  
Amino Acids ◽  
Quantitative Analysis ◽  
Amino Acid ◽  
Ion Exchange ◽  
Free Amino Acids ◽  
Free Amino ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Butyl Esters ◽  
Tlc Analysis

Abstract Qualitative chromatographic methods for the separation of free amino acids in table sirups are presented to aid in the development of chemical indices of composition which may be useful in establishing the identity of sirups and detecting their adulteration. Free amino acids in 2 table sirups were isolated on ion exchange columns and eluted with dilute ammonia. The concentrated amino acid mixture in the eluate was spotted directly on silica gel G plates for TLC analysis, or the amino acids were converted to their N-trifluoroacetyl n-butyl esters for GLC analysis. As many as 16 amino acids were qualitatively separated and identified and a potential for quantitative analysis was demonstrated.

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