Ammonia uptake in inactive muscles during exercise in man.
Bangsbo, J., B. Kiens, and E. A. Richter.
Copenhagen Muscle Research Center, August Krogh Institute,
University of Copenhagen, Denmark
APStracts 2:0169G, 1995.
The present study examined NH3 (ammonia and ammonium) uptake in
resting leg muscle. Six male subjects performed intermittent arm
exercise at various intensities in two separate 32-min periods (Part
I and Part II) and in one subsequent 20-min period in which one
legged exercise was also performed (Part III). The arterial plasma
NH3 concentration was 79.6+/-9.6 (+/-SE) [mu]mol x l-1 at rest and
88.1+/-9.1, 98.1+/-8.1 and 210.2+/-7.5 [mu]mol x l-1 after 10 min of
Part I, Part II and Part III, respectively. The corresponding NH3
uptakes in the resting leg were 3.3+/-1.3 (rest), 7.8+/-1.5, 14.0+/
-4.5 and 57.7+/-18.3 [mu]mol x min-1. Throughout each exercise period
a net uptake of NH3 was observed in the resting leg (P<0.05),
but uptake decreased to resting values within 5 min of termination of
exercise. The muscle NH3 concentration of 195.1+/-15.0 [mu]mol x kg-1
w.w. at rest was largely unchanged throughout the experiment. The
present data suggest that resting muscles extract NH3 and contribute
significantly to clearance of NH3 during exercise and in early
recovery from exercise. The extracted NH3 appears to be metabolized
within the resting muscles.
Received 24 April 1995; accepted in final form 10 August 1995.
APS Manuscript Number G187-5.
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.