AJP - Renal Physiology, Vol 265, Issue 2 257-F263, Copyright © 1993 by American Physiological Society
Mechanisms of adaptation to proteinuria in adriamycin nephrosis
E. J. Choi, R. C. May, J. Bailey, T. Masud, A. Dixon and B. J. Maroni
Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322.
To evaluate the impact of urinary protein losses on whole body protein
turnover (WBPT) independent of acidosis or uremia, we utilized a model of
unilateral adriamycin nephrosis. Control rats were matched by weight to
nephrotic rats and pair fed 22% protein chow for 14-18 days; urinary urea
nitrogen (UUN) was measured on day 12, and leucine turnover measurement was
performed on the final day. Growth rates of nephrotic and pair-fed control
rats did not differ during the first 2 wk of pair feeding; thereafter, a
small difference in growth could be detected. Despite an identical intake
of dietary protein, UUN excretion was 29% less in the nephrotic rats (P
< or = 0.02). Fasting whole body protein synthesis and degradation did
not differ between nephrotic and control rats; in contrast, leucine
oxidation decreased by 21% in nephrosis (P < 0.05). On the basis of near
normal growth and normal rates of WBPT, we conclude that nephrotic rats fed
ad libitum can adapt to the stress of continuous protein losses. A
reduction in amino acid oxidation and UUN excretion were the primary
mechanisms responsible for protein conservation in experimental nephrosis.
