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Leucine metabolism in human newborns
1Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland Metropolitan General Hospital, Ohio 44109.
The American Journal of Physiology
|December 1, 1987
Summary
Newborn birth weight correlates with leucine metabolism, with higher rates in infants compared to adults. These findings highlight protein turnover during early development.
Area of Science:
- Biochemistry
- Human Physiology
- Neonatal Metabolism
Background:
- Leucine metabolism and energy expenditure are critical for growth and development.
- Understanding these processes in newborns versus adults can reveal developmental differences.
Purpose of the Study:
- To investigate the relationship between newborn birth weight and leucine metabolism.
- To compare leucine and energy metabolism in newborns during rapid growth versus adults in a non-growth phase.
Main Methods:
- Utilized primed constant L-[1-13C]leucine infusion and respiratory calorimetry.
- Measured leucine kinetics and energy expenditure in the postabsorptive state.
- Included 12 full-term newborns and 11 normal adults.
Main Results:
- A significant positive correlation was found between newborn birth weight and leucine flux.
- Newborns exhibited higher leucine flux, oxidation, and energy expenditure per kilogram body weight than adults.
- When normalized to metabolic body weight (W0.75), rates were similar between newborns and adults.
Conclusions:
- Newborn birth weight is linked to protein metabolism, indicated by leucine flux.
- Elevated leucine flux in newborns likely reflects rapid protein remodeling during development, even when fasting.
- Allometric exponents for leucine flux and energy expenditure align with the metabolic weight exponent (0.75).