Extremity amino acid metabolism during starvation and intravenous refeeding in humans

This study was designed to evaluate peripheral tissue amino acid metabolism in normal subjects who underwent starvation followed by intravenous administration of a nutritional repletion regimen with varying nonprotein caloric sources. Extremity amino acid (AA), arteriovenous differences, and blood flow were measured across forearm and/or leg of 12 healthy male subjects. Plasma AA flux [(arterial concentration - venous concentration) X flow X (1 - hematocrit); ml X min-1 X 100 ml tissue-1] was determined postabsorptively (PA), after 10 days of starvation (ST) and on the 10th day of intravenous feeding (IVF). There was a significant (P less than 0.05) decrease in efflux of total amino acids during the starvation study (-345 +/- 74) compared with the PA study (-1,463 +/- 263). Peripheral tissue AA uptake increased significantly (P less than 0.05) after 10 days of IVF (+276 +/- 79) compared with both PA and ST studies. There were no significant differences in extremity AA flux between those subjects who received 100% dextrose and those receiving 50% dextrose-50% lipid as a nonprotein caloric source. Linear relationships of AA infusion rate (IR) to AA flux (r = 0.845, P less than 0.001) and AA IR to [AA]art IVF (r = 0.842, p less than 0.001) were observed during IVF. Results of this study suggest that extremity flux determinations during IVF cannot be interpreted without correction for AA availability as reflected by AA infusion rate.

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Biochemische Aspekte des Aminosäuren-Stoffwechsels bei Psoriasis vulgaris / Biochemical Aspects of Amino Acid Metabolism in Psoriasis vulgaris

Zeitschrift für Naturforschung C ◽

10.1515/znc-1973-7-816 ◽

1973 ◽

Vol 28 (7-8) ◽

pp. 449-451 ◽

Cited By ~ 2

Author(s):

G. Peter ◽

H. Angst ◽

U. Koch

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Free Amino Acids ◽

Free Amino ◽

Amino Acid Metabolism ◽

Acid Metabolism ◽

Psoriasis Vulgaris ◽

Normal Subjects ◽

Pathological Process

Free and protein-bound amino acids in serum and scales were investigated. In serum the bound amino acids of psoriatics are significantly higher with exception of Pro, Met, Tyr and Phe in contrast to normal subjects. For free amino acids the differences between normal subjects and psoriatics found in serum and scales are not significant. Results are discussed in relation to the single amino acids and the biochemical correlations are outlined which takes the pathological process as a basis.

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Exercise-Mediated Peripheral Tissue and Whole-Body Amino Acid Metabolism during Intravenous Feeding in Normal Man

Clinical Science ◽

10.1042/cs0770113 ◽

1989 ◽

Vol 77 (1) ◽

pp. 113-120 ◽

Cited By ~ 13

Author(s):

James D. Albert ◽

Dwight E. Matthews ◽

Adrian Legaspi ◽

Kevin J. Tracey ◽

Malayappa Jeevanandam ◽

...

Keyword(s):

Amino Acid ◽

Amino Acid Metabolism ◽

Acid Metabolism ◽

Submaximal Exercise ◽

Peripheral Tissue ◽

Whole Body ◽

Total Amino Acid ◽

Body Protein ◽

Daily Exercise ◽

Amino Acid Flux

1. The effect of a daily submaximal exercise regimen on whole-body and peripheral tissue amino acid metabolism during weight-stable intravenous feeding (IVF) was evaluated in 11 normal volunteers. Five of the subjects performed 1 h of daily bicycle exercise at 75 W during IVF, while the remaining six subjects received IVF without daily exercise. Body nitrogen balance, leg and forearm plasma amino acid flux and whole-body kinetics were measured before and on day 10 of IVF using a [1-13C]leucine and [15N]glycine tracer. 2. At the end of the IVF period, exercised subjects demonstrated leg uptake of total amino acids (237 ± 103 nmol min−1 100 ml−1 of tissue, mean ± sem) which was significantly (P < 0.05) different than in non-exercised subjects (− 1101 ± 253 nmol min−1 100 ml−1 of tissue). 3. In the non-exercised forearm, a significant (P < 0.05) decrease in total amino acid flux was observed in exercised subjects (− 162 ± 88 nmol min−1 100 ml−1 of tissue) compared with non-exercised subjects (−460 ± 105 nmol min−1 100 ml−1 of tissue) on day 10 of IVF. 4. Efflux of 3-methylhistidine significantly (P < 0.05) decreased from the leg in those subjects who performed daily exercise (−0.29 ± 0.12 nmol min−1 100 ml−1 of tissue) compared with those subjects receiving IVF without daily exercise (− 1.46 ± 0.35 nmol min−1 100 ml−1 of tissue). 5. Although IVF increased whole-body leucine turnover in both exercised and non-exercised subjects, only exercised subjects demonstrated a significant (P < 0.05) increase in leucine oxidation which was proportionate to an increased muscle uptake of leucine. Whole-body protein breakdown, as assessed by [15N]glycine, was significantly (P < 0.05) decreased in exercised subjects compared with non-exercised subjects during IVF. 6. These data demonstrate that daily submaximal exercise produced a systemic as well as limb-specific enhancement of amino acid balance in muscle, providing an anti-catabolic response under conditions of partial immobility induced by hospitalization.

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