A compartmental model of 3-methylhistidine metabolism in
humans.
Rathmacher, John A., Paul J. Flakoll, and Steven L. Nissen.
Department of Animal Science, Iowa State University, Ames, Iowa
50011, Department of Surgery, Vanderbilt University School of
Medicine, Nashville, Tennessee 37232
APStracts 2:0056E, 1995.
Urinary 3-methylhistidine (3MH) excretion has been proposed as a
noninvasive in vivo marker of muscle protein breakdown, but such
analysis requires quantitative collection of urine and yields little
details about the metabolism of 3MH. In this study, we propose that
data from a single bolus dose of tracer and serial blood samples over
72 h can be described by a kinetic model which defines 3MH metabolism
in humans. Plasma concentration of the tracer was described by a
linear time-invariant 3-compartment model. The model defines masses
and fluxes of 3MH within the subjects and, in particular, the
intracellular de novo production of 3MH. The de novo production of
3MH as calculated by the model was not different from that calculated
via the traditional collection of urinary 3MH (3.09 vs. 2.57 [mu]mol
x kg-1 x d-1, respectively, P>0.30). These data indicate that 3MH
production can be measured by a compartmental model which can be used
to measure muscle proteolysis without quantitative urine collections.
Received 8 August 1994; accepted in final form 24 March 1995.
APS Manuscript Number E313-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.