Display Settings:

Format

Send to:

Choose Destination
J Appl Physiol (1985). 2008 Dec;105(6):1959-66. doi: 10.1152/japplphysiol.90352.2008. Epub 2008 Sep 18.

Positive net movements of amino acids in the hindlimb after overnight food deprivation contribute to sustaining the elevated anabolism of neonatal pigs.

Author information

  • 1Rowett Institute of Nutrition and Health, Greenburn Rd., Bucksburn, Aberdeen AB21 9SB, UK. c.thivierge@rowett.ac.uk

Abstract

During the neonatal period, high protein breakdown rate is a metabolic process inherent to elevated rates of protein accretion in skeletal muscle. To determine the relationship between hindlimb net movements of essential and nonessential amino acids in the regulation of hindlimb protein breakdown during an overnight fasting-feeding cycle, we infused overnight-food-deprived 10- and 28-day-old piglets with [1-(13)C]phenylalanine and [ring-(2)H(4)]tyrosine over 7 h (during 3 h of fasting and then during 4 h of feeding). Extraction rates for aspartate and glutamate after an overnight fast were 15% and 51% in the 10-day-old compared with 6% and 25% in the 28-day-old (P < 0.05) piglets, suggesting an altered requirement for precursors of amino acids to shuttle nitrogen to the liver as early life progresses. This occurred simultaneously with marginal positive hindlimb net balance of essential amino acids after an overnight fast, with negative net release of many nonessential amino acids, such as alanine, asparagine, glutamine, glycine, and proline. This suggests that newborn muscle does not undergo significant protein mobilization after a short period of fasting in support of an elevated rate of protein accretion. Furthermore, tyrosine efflux from hindlimb breakdown between overnight fasting and feeding periods was not different in the 10-day-old piglets, for which tyrosine was limiting, but when tyrosine supply balanced requirements in the 28-day-old piglet, hindlimb efflux was increased (P = 0.01). The results of the present study indicate that proteolysis and net movements of amino acids are coordinated mechanisms that sustain the elevated rate of net protein accretion during overnight feeding-fasting cycles in the neonate.

PMID:
18801965
[PubMed - indexed for MEDLINE]
PMCID:
PMC2612466
Free PMC Article

Images from this publication.See all images (1)Free text

Fig. 1.
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk