AJP - Endocrinology and Metabolism, Vol 251, Issue 5 604-E610, Copyright © 1986 by American Physiological Society
Extremity amino acid metabolism during starvation and intravenous refeeding in humans
J. D. Albert, A. Legaspi, G. D. Horowitz, K. J. Tracey, M. F. Brennan and S. F. Lowry
This study was designed to evaluate peripheral tissue amino acid metabolism
in normal subjects who underwent starvation followed by intravenous
administration of a nutritional repletion regimen with varying nonprotein
caloric sources. Extremity amino acid (AA), arteriovenous differences, and
blood flow were measured across forearm and/or leg of 12 healthy male
subjects. Plasma AA flux [(arterial concentration - venous concentration) X
flow X (1 - hematocrit); ml X min-1 X 100 ml tissue-1] was determined
postabsorptively (PA), after 10 days of starvation (ST) and on the 10th day
of intravenous feeding (IVF). There was a significant (P less than 0.05)
decrease in efflux of total amino acids during the starvation study (-345
+/- 74) compared with the PA study (-1,463 +/- 263). Peripheral tissue AA
uptake increased significantly (P less than 0.05) after 10 days of IVF
(+276 +/- 79) compared with both PA and ST studies. There were no
significant differences in extremity AA flux between those subjects who
received 100% dextrose and those receiving 50% dextrose-50% lipid as a
nonprotein caloric source. Linear relationships of AA infusion rate (IR) to
AA flux (r = 0.845, P less than 0.001) and AA IR to [AA]art IVF (r = 0.842,
p less than 0.001) were observed during IVF. Results of this study suggest
that extremity flux determinations during IVF cannot be interpreted without
correction for AA availability as reflected by AA infusion rate.
