Influence of insulin on blood levels of branched chain keto and amino acids in man

Schauder, P.; Schröder, Karsten; Matthaei, D.; Henning, Hans; Langenbeck, U.

doi:10.1016/0026-0495(83)90038-0

Cited by 30 publications

(11 citation statements)

References 23 publications

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“…The present experiment demonstrates that hypoglycemia increases the uptake of the gluconeogenic amino acids and leaves unchanged the release of the branched chain. Our results are also in agreement with studies in humans that achieved hypoglycemia with a bolus of insulin (39) or with the discontinuation of the glucose infusion after a euglycemic clamp (40): in both of them, the leucine concentrations remained below the postabsorptive concentration in the first 2-3 h of hypoglycemia, despite a rapid discontinuation of hyperinsulinemia. In regard to the effect of hypoglycemia on the gluconeogenic amino acids, our results agree with a recent study from Meyer et al (41) that showed that hypoglycemia potentiates the insulin suppression of the glutamine and the alanine concentrations.…”

Section: Discussionsupporting

confidence: 81%

Effect of hypoglycemia on amino acid and protein metabolism in healthy humans.

et al. 2000

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In response to hypoglycemia, healthy individuals rapidly antagonize insulin action on glucose and lipid metabolism, but the effects on protein metabolism are unclear. Because amino acids are an important substrate for gluconeogenesis and a fuel alternative to glucose for oxidation, we evaluated whether hypoglycemia antagonizes the hypoaminoacidemic and the antiproteolytic effects of insulin and changes the de novo synthesis of glutamine, a gluconeogenic amino acid. To this purpose, in 7 healthy subjects, we performed 2 studies, 3.5 h each, at similar insulin but different glucose concentrations (i.e., 4.9 ± 0.1 mmol/l [euglycemic clamp] or 2.9 ± 0.2 mmol/l [hypoglycemic clamp]). As expected, hypoglycemia antagonized the insulin suppression of glucose production achieved in euglycemia (from 21 ± 15 to 116 ± 12% of basal, P < 0.001), the stimulation of glucose uptake (from 207 ± 28 to 103 ± 7% of basal, P < 0.01) and the suppression of circulating free fatty acids (from 30 ± 5 to 80 ± 17% of basal, P < 0.001). In contrast, hypoglycemia increased the insulin suppression of circulating leucine (from 63 ± 1 to 46 ± 2% of basal, P < 0.001) and phenylalanine (from 79 ± 3 to 64 ± 3% of basal, P < 0.001) concentrations. Hypoglycemia did not change the insulin suppression of proteolysis (from 79 ± 2 to 82 ± 4% of basal, P < 0.001). However, hypoglycemia doubled the insulin suppression of the glutamine concentrations (from 84 ± 3 to 63 ± 3% of basal, P < 0.01) in the absence of significant changes in the glutamine rate of appearance, but it also caused an imbalance between glutamine uptake and release. This study demonstrates that successful counterregulation does not affect proteolysis. Moreover, it does not increase the availability of circulating amino acids by de novo synthesis. In contrast, despite the lower concentration of circulating amino acids, hypoglycemia increases the uptake of glutamine that can be used for gluconeogenesis and as a fuel alternative to glucose.

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Section: Discussionsupporting

confidence: 81%

Effect of hypoglycemia on amino acid and protein metabolism in healthy humans.

et al. 2000

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“…A small augmentation of BUN was observed after 90 min. As wc demonstrated earlier, blood levels of BCAA and BCKA did not change in healthy controls given physiological saline during a 3-hour observation period [13].…”

Section: Resultsmentioning

confidence: 53%

Serum Branched-Chain Amino and Keto Acid Response to a Protein-Rich Meal in Man

Schauder¹,

Schröder²,

Langenbeck³

1984

Ann Nutr Metab

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In 8 healthy volunteers blood levels of branched-chain amino (BCAA) and keto acids (BCKA) were determined in response to a protein-rich meal. Serum concentrations of leucine, isoleucine, valine, Α-ketoisocaproic acid and Α-keto-Β-methyl-n-valeric acid increased within 30 min and continued to rise throughout the observation. Only the keto analog of valine remained unaffected. As the BCAA increased significantly more percentagewise than their keto analogs, the ratios between amino and keto acids became augmented. It is suggested that (1) augmentation of keto acids may reflect transamination of amino acids rather than intestinal uptake; (2) the overall capacity of the organism for decarboxylation of ketovaline is greater than for the other keto acids, and (3) augmentation of the ratio between BCAA and BCKA may favor the storage of amino acids from the protein load into the body’s protein stores.

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“…Rates of amino acid entry into and removal from plasma are determined by amino acid utilization for protein synthesis, liberation from tissue proteins via proteolysis, oxidation, and in the case ofthe dispensable amino acids, via their de novo synthesis. Insulin produces reductions in plasma amino acids; the effect is most marked for the branched-chain amino acids (BCAA)' and minimal for alanine (1)(2)(3). To clarify the specific mechanisms responsible for the insulin-dependent reduction in plasma BCAA levels and to examine the subsequent effects on alanine metabolism, we have combined stable isotope tracer dilution kinetics in combination with the euglycemic insulin clamp technique in healthy young men.…”

Section: Introductionmentioning

confidence: 99%

Insulin-mediated reduction of whole body protein breakdown. Dose-response effects on leucine metabolism in postabsorptive men.

Fukagawa¹,

Minaker²,

Rowe³

et al. 1985

J. Clin. Invest.

356

118

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In vivo effects of insulin on plasma leucine and alanine kinetics were determined in healthy postabsorptive young men (n = 5) Leucine oxidation estimated from the GC-enrichment of expired CO2 and plasma leucine (12±1 ,umolkg. hr-) and from the '3C-enrichment of CO2 and plasma a-ketoisocaproate (19±2 Mumollkg. hr-') increased at the 16 ,U/ml insulin level to 16±1 and 24±2 ,mol(kg. h)-', respectively (P < 0.05 for each), but did not increase at higher insulin levels. Alanine flux (206±13 Amol(kg-h)-Y) did not increase during the clamp, but alanine de novo synthesis increased in all studies from basal rates of 150±13 to 168±23, 185+21, 213±29, and 187±15 ,umol(kg. h)-1 at 16, 29, 75, and 2,407 MU/ml insulin levels, respectively (P < 0.05). These data indicate the presence ofinsulin-dependent suppression of leucine entry into the plasma compartment in man secondary to a reduction in proteolysis and the stimulation of alanine synthesis during euglycemic hyperinsulinemia.

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Influence of insulin on blood levels of branched chain keto and amino acids in man

Cited by 30 publications

References 23 publications

Effect of hypoglycemia on amino acid and protein metabolism in healthy humans.

Effect of hypoglycemia on amino acid and protein metabolism in healthy humans.

Serum Branched-Chain Amino and Keto Acid Response to a Protein-Rich Meal in Man

Insulin-mediated reduction of whole body protein breakdown. Dose-response effects on leucine metabolism in postabsorptive men.

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