AJP - Endocrinology and Metabolism, Vol 262, Issue 2 E240-E245, Copyright © 1992 by American Physiological Society
Effect of acute food restriction on pulmonary growth and protein turnover in preterm guinea pigs
F. J. Kelly, J. C. Fussell and T. D. Postle
Department of Human Nutrition, University of Southampton, United Kingdom.
The effects of food restriction on the growth and protein turnover of the
immature lung were investigated. Preterm guinea pigs, delivered by cesarean
section at 65 days gestation (term = 68 days), were given free access to a
lactating dam or restricted from feeding for 48 h. Food restriction
resulted in significantly reduced body and lung (P less than 0.05) weight
compared with fed controls. The rate of pulmonary protein synthesis
determined in vivo was reduced by 33% in the food-restricted pups (28.9 +/-
10.2 vs. 19.4 +/- 4.5%, P less than 0.05 for control and food-restricted
pups, respectively), whereas the calculated rate of protein breakdown
remained unchanged. The inhibition of protein synthesis was accounted for
by a 36% decrease in ribosomal efficiency (11.03 +/- 2.61 vs. 7.04 +/-
1.26%, P less than 0.01 for control and food-restricted pups,
respectively), whereas ribosomal capacity was unaltered. Polyribosomal
analysis indicated an increase in the proportion of RNA present in
polysomes and a fall in the free monomer pool (26%), suggesting that food
restriction blocked translation by reducing the rate of peptide chain
elongation. This finding was confirmed by the analysis of ribosome transit
times, which indicated a significant increase in the elongation rate in the
lungs from food-restricted pups (0.51 +/- 0.11 vs. 0.94 +/- 0.19 min, P
less than 0.05 for control and food-restricted pups, respectively). These
results imply that nutrient supply plays an important role in protein
deposition and hence growth and repair capacity of the immature lung.
