Affiliation:
1. Departments of Pediatrics and Biochemistry, Robert Schwartz M.D. Center for Metabolism and Nutrition, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44109-1998
Abstract
Glutamine kinetics and its relation to transamination of leucine and urea synthesis were quantified in 16 appropriate-for-gestational-age infants, four small-for-gestational-age infants, and seven infants of diabetic mothers. Kinetics were measured between 4 and 5 h after the last feed (fasting) and in response to formula feeding using [5-15N]glutamine, [1-13C,15N]leucine, [2H5]phenylalanine, and [15N2]urea tracers. Leucine nitrogen and glutamine kinetics during fasting were significantly higher than those reported in adults. De novo synthesis accounted for ∼85% of glutamine turnover. In response to formula feeding, a significant increase ( P = 0.04) in leucine nitrogen turnover was observed, whereas a significant decrease ( P = 0.002) in glutamine and urea rate of appearance was seen. The rate of appearance of leucine nitrogen was positively correlated ( r2= 0.59, P = 0.001) with glutamine turnover. Glutamine flux was negatively correlated ( r2= 0.39, P = 0.02) with the rate of urea synthesis. These data suggest that, in the human newborn, glutamine turnover is related to a high anaplerotic flux into the tricarboxylic acid cycle as a consequence of a high rate of protein turnover. The negative relationship between glutamine turnover and the irreversible oxidation of protein (urea synthesis) suggests an important role of glutamine as a nitrogen source for other synthetic processes and accretion of body proteins.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology,Endocrinology, Diabetes and Metabolism
Cited by
15 articles.
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