In vivo amino acid metabolism of gut and liver during short and
prolonged starvation.
Blaauw, I. De, N. E. P. Deutz, M. F. Von Meyenfeldt.
Department of Surgery, University of Limburg, Fac II, P.O. Box 616,
NL-6200 MD Maastricht, The Netherlands
APStracts 2:0171G, 1995.
During starvation splanchnic organs are proportionally more affected
by protein loss than other organs. Amino acid membrane transport is
one of the regulating mechanisms of protein turnover but until now in
vivo data are lacking. To study in vivo phenylalanine and tyrosine
membrane transport and protein turnover in splanchnic organs, a
primed continuous infusion of L-[2,6-3H]Phenylalanine was given to
control rats (postabsorptive) and after short (40 hours) and
prolonged (112 hours) starvation. Data were analyzed using a three
compartment model previously used in muscle membrane transport
studies. Inward and outward amino acid plasma-tissue membrane
transport rates in both the liver and gut were upregulated after
prolonged starvation. Metabolic shunting of phenylalanine and
tyrosine increased in the gut but decreased to zero in the liver
after prolonged starvation. In conjunction with this, gut and liver
protein turnover increased after prolonged starvation. In the liver
the net uptake of gluconeogenic precursors also increased, indicative
for increased gluconeogenesis. The observed changes in amino acid
metabolism in both splanchnic organs after prolonged starvation, may
reflect an adaptation of the gut and liver to nutritional deprivation
and could be of benefit during refeeding.
Received 15 February 1995; accepted in final form 10 August 1995.
APS Manuscript Number G69-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.