Leucine and phenylalanine kinetics during mixed meal ingestion: a multiple tracer approach

Biolo, Gianni; Tessari, Paolo; Inchiostro, S.; Bruttomesso, Daniela; Fongher, C.; Sabadin, L; Fratton, M. G.; Valerio, Anna; Tiengo, Antonio

doi:10.1152/ajpendo.1992.262.4.e455

Cited by 79 publications

(102 citation statements)

References 11 publications

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“…This also included comparisons between essential and non-essential AA, where only limited information is available (e.g. Biolo et al [17]; Chung et al [24]). The data at 1.5 M were similar to those from a comparable intake in an earlier study [10], but were lower for some non essential AA (plasma ILR = 10.34 mmol·h -1 vs. 6.95 mmol·h -1 for glycine, 17.12 mmol·h -1 vs. 12.26 mmol·h -1 for glutamate, 5.43 mmol·h -1 vs. 2.81 mmol·h -1 for aspartate).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, whether the same pattern of response occurs for other tissues (and thus whole body protein metabolism) has not been examined. Metabolic responses and utilisation of the AA by other tissues (notably the liver and the digestive tract) may differ with intake [10,17,18]. As a consequence, the influence of the tissues that may respond curvilinearly to intake (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Effect of intake on whole body plasma amino acid kinetics in sheep

Savary-Auzeloux¹,

Hoskin

Lobley³

2003

Reprod. Nutr. Dev.

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-While both the quantity and quality of food ingested are potent regulators of whole body protein metabolism in ruminants, little data are available on responses across a wide range of intakes. The current study examined the responses in whole body protein flux (PrF) to such intake changes and compared these with the responses across the hind-quarters (in a companion study). Six growing sheep (6-8 months, 30-35 kg) received each of four intakes of dried grass pellets (0.5, 1.0, 1.5 and 2.5 times maintenance energy; M) for a minimum of 7 days. At each intake, a mixture of U-13 C amino-acids (AA) was infused intravenously for 10 h. Arterial plasma and blood were obtained over the last 4 h of infusion and the concentrations and the enrichments of thirteen 13 C labelled AA were determined. The absolute values for plasma Irreversible Loss Rate (ILR) but also converted PrF varied between the AA. PrF values were lower for histidine, methionine, aspartate, glycine and proline (range 68 to 174 g·d -1 at 1.5 M) than for isoleucine, leucine, valine and glutamate (range 275 to 400 g·d -1 at 1.5 M). These discrepancies may be explained by (1) the differential AA removal by the splanchnic tissues, (2) the de novo synthesis of the non-essential AA, (3) the transfer of AA from the erythrocytes or plasma to the tissues. The first two assumptions require further investigation whereas recent work has shown a minor role for AA transfers between erythrocytes and tissues. For most AA, ILR and PrF responded linearly to intake but curvilinear responses were observed for phenylalanine, lysine, leucine, isoleucine and tyrosine. These differences were not due to hind-quarter metabolism and may involve the digestive tract and liver.intake / whole body / kinetics / ovine / amino acid Reprod. Nutr. Dev. 43 (2003) 117-129 117

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of intake on whole body plasma amino acid kinetics in sheep

Savary-Auzeloux¹,

Hoskin

Lobley³

2003

Reprod. Nutr. Dev.

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“…Standard regression curves were applied in all isotopic enrichment analyses to assess the linearity of the mass spectrometer and to control for the loss of tracer. Enrichments (MPE) were corrected for the natural abundance of 13 C phenylalanine (Biolo et al 1992). …”

Section: Plasma Analysesmentioning

confidence: 99%

The muscle protein synthetic response to the combined ingestion of protein and carbohydrate is not impaired in healthy older men

Kiskini

Hamer

Wall

et al. 2013

AGE

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Aging is associated with a progressive decline in skeletal muscle mass. It has been hypothesized that an attenuated muscle protein synthetic response to the main anabolic stimuli may contribute to the age-related loss of muscle tissue. The aim of the present study was to compare the muscle protein synthetic response following ingestion of a meal-like amount of dietary protein plus carbohydrate between healthy young and older men.

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“…Recently, a model using stable isotopes was described that measures the uptake of leucine administered to the GI tract by splanchnic tissues (8,9). In adult human subjects, 17-25% of orally administered leucine is removed by the splanchnic tissues on first pass (8,10,11). Studies show that 13-40% of the leucine was released as KIC to the systemic circulation (11,12).…”

mentioning

confidence: 99%

“…The extent of splanchnic uptake varies among the different amino acids. Studies in adults showed that 40% of the leucine appearing in plasma is derived from intestinal sources, compared with 20% for phenylalanine (10). The splanchnic uptake of amino acids might also be different for patients of different ages.…”

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confidence: 99%

Effect of Minimal Enteral Feeding on Splanchnic Uptake of Leucine in the Postabsorptive State in Preterm Infants

et al. 2003

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We conducted a controlled, randomized trial to study the effect of minimal enteral feeding on leucine uptake by splanchnic tissues, as an indicator of maturation of these tissues, in preterm infants in the first week of life. Within a few hours after birth, while receiving only glucose, a primed constant infusion of [1-13 C]-leucine was started and continued for 5 h via the nasogastric tube, whereas 5,5,5 D3-leucine was infused intravenously (for both tracers, priming dose 2 mg/kg, continuous infusion 2 mg/kg/h). Patients were thereafter randomized to receive solely parenteral nutrition (C), parenteral nutrition and 20 mL breast milk/kg/d (BM), or parenteral nutrition and 20 mL formula/kg/d (F). On d 7, the measurements were repeated, after discontinuing the oral intake for 5 h. Fourteen infants were included in group C, 12 in group BM, and 12 in group F. There was no difference in energy intake or nitrogen balance at any time. On d 1, plasma enrichment for the nasogastric tracer was lower than for the intravenous tracer for all three groups, both for leucine and for ␣-keto-isocaproic acid. On d 7, the enrichment for leucine and ␣-keto-isocaproic acid for the nasogastric tracer was lower than for the intravenous tracer for the groups BM and F (BM: 3.65 Ϯ 1.20 nasogastric versus 4.64 Ϯ 0.64 i.v.; F: 4.37 Ϯ 1.14 nasogastric versus 5.21 Ϯ 0.9 i.v.). In the control group, there was no difference between tracers. The lower plasma enrichment for the nasogastric tracer compared with the intravenous tracer suggests uptake of leucine by the splanchnic tissues. We conclude that minimal enteral feeding-even in low volumes of 20 mL/kg/dincreases the leucine uptake by the splanchnic tissue. We speculate that this reflects a higher protein synthesis of splanchnic tissues in the groups receiving enteral nutrition. Advances in perinatal care have lead to a significant increase in survival of preterm infants. There has been an increasing recognition that nutrition plays an important role in the survival and subsequent growth and development of VLBW infants. Parenteral nutrition is used extensively in clinical care of preterm infants. The timing of initiation of enteral feeding in VLBW infants is still controversial. On one hand, anxiety about necrotizing enterocolitis has prompted neonatologists to delay enteral feeding in VLBW infants. On the other hand, animal studies have shown a negative effect of replacing enteral with total parenteral nutrition on gut morphology and function (1-5). Minimal enteral feeding has been shown to improve gut maturation, as evidenced by improved motility (6, 7). The effect of minimal enteral feeding on protein metabolism of splanchnic tissues, an indicator of anabolism of splanchnic tissues, is unknown. Recently, a model using stable isotopes was described that measures the uptake of leucine administered to the GI tract by splanchnic tissues (8,9). In adult human subjects, 17-25% of orally administered leucine is removed by the splanchnic tissues on first pass (8,10,11). Studies show that 13-40% o...

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Leucine and phenylalanine kinetics during mixed meal ingestion: a multiple tracer approach

Cited by 79 publications

References 11 publications

Effect of intake on whole body plasma amino acid kinetics in sheep

Effect of intake on whole body plasma amino acid kinetics in sheep

The muscle protein synthetic response to the combined ingestion of protein and carbohydrate is not impaired in healthy older men

Effect of Minimal Enteral Feeding on Splanchnic Uptake of Leucine in the Postabsorptive State in Preterm Infants

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