AJP - Endocrinology and Metabolism, Vol 238, Issue 1 46-E52, Copyright © 1980 by American Physiological Society
Turnover of total proteins and ornithine aminotransferase during liver regeneration in rats
S. L. Augustine and R. W. Swick
The recovery of approximately 40% of the total liver protein during the
first day after partial hepatectomy was shown to be due to the near
cessation of protein breakdown rather than to an increase in protein
synthesis. The decrease in degradation of total protein was less if rats
were adrenalectomized or protein-depleted prior to partial hepatectomy. The
effect of these treatments originally suggested that changes in free amino
acid levels in liver might be related to the rate of protein degradation.
However, no correlation was found between levels of total free amino acids
and rates of breakdown. Measurements of individual amino acids during liver
regeneration suggested that levels of free methionine and phenylalanine,
amino acids that have been found to lower rates of protein degradation in
vitro, are not correlated with rates of breakdown in vivo. The difference
between the fractional rate of ornithine aminotransferase degradation
(0.68/day and 0.28/day in sham-hepatectomized and partially hepatectomized
rats, respectively) was sufficient to account for the higher level of this
protein 3 days after surgery in the latter group.
