Effects of feeding on protein turnover in healthy children and in children with cystic fibrosis.
We hypothesized that there is less suppression of whole-body protein breakdown with feeding in patients with cystic fibrosis (CF) who exhibit decreased insulin secretion after a single meal. Using [1-13C]leucine, we measured rates of nonoxidative leucine disappearance (whole-body protein synthesis) and protein breakdown in nine CF patients (6-11 y of age) and five healthy control subjects (8-10 y of age) during feeding and fasting. In the CF patients, synthesis and breakdown (x +/- SD) were 172 +/- 61 and 157 +/- 67 mumol.kg-1.h-1 during feeding and 140 +/- 24 and 178 +/- 26 mumol.kg-1.h-1 during fasting. The respective control values were 129 +/- 27 and 114 +/- 20 mumol.kg-1.h-1 during feeding and 136 +/- 13 and 173 +/- 18 mumol.kg-1.h-1 during fasting. Leucine balance was nearly identical in the two groups. By analysis of variance, there was a significant effect of feeding on protein breakdown but no difference between the groups. However, when each group was analyzed separately, feeding resulted in a 34% decrease in breakdown in the control subjects (P = 0.001) and a 23% increase in synthesis in the CF group (P = 0.058). Plasma insulin concentrations did not differ in the two groups. Thus, feeding may affect protein turnover differently in children with CF than in control children independently of plasma insulin concentration.
Kien
C L
CL
Children's Hospital Research Foundation, Columbus, OH, USA.
Zipf
W B
WB
Horswill
C A
CA
Denne
S C
SC
McCoy
K S
KS
O'Dorisio
T M
TM
D016022:Case-Control Studies; D002648:Child; D003550:Cystic Fibrosis / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D004435:Eating / Q000502:physiology*; D005215:Fasting / Q000378:metabolism; D005260:Female; D005526:Food, Formulated; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood; D007930:Leucine / Q000008:administration & dosage / Q000378:metabolism; D008297:Male; D012016:Reference Values
D004044:Dietary Proteins; D007328:Insulin; D007930:Leucine