Lactate and epinephrine during exercise in altitude natives.
Kayser, Bengt, Roland Favier, Guido Ferretti, Dominique Desplanches,
Hilde Spielvogel, Harry Koubi, Brigitte Sempore, and Hans Hoppeler.
D[acute]epartement de Physiologie, Centre M[acute]edical
Universitaire, 1211 Gen[grave]eve 4, Switzerland; URA 1341 CNRS,
Laboratoire de Physiologie, Universit[acute]e Claude Bernard, 69373
Lyon, France; Instituto Boliviano de Biolog[acute]ia de Altura,
Universidad Mayor de San Andr[acute]es, Casilla 717, La Paz, Bolivia;
Anatomisches Institut, Universit[umlaut]at Bern, B[umlaut]uhlstrasse,
1000 Berne, Switzerland
APStracts 3:0367A, 1996.
We tested the hypothesis that the reported low blood lactate ([La])
accumulation during exercise in altitude native humans is refractory
to hypoxia-normoxia transitions by investigating if acute changes in
inspiratory oxygen (FiO2) affect the [La] vs. power output ()
relationship, or alternatively, as reported for lowlanders, if
changes in [La] vs. upon changes in FiO2 are related to changes in
blood epinephrine [epi]. Altitude natives (n=8, 24+/-1 yr, 62+/-3 kg,
167+/-2 cm, +/-SEM) in LaPaz (3600 m) performed incremental exercise
with two legs and one leg in chronic hypoxia (CH) and acute normoxia
(AN). Submaximal one and two leg vs. relationships were not altered
by FiO2. AN increased two leg peak by 10% and peak by 7%. AN
paradoxically decreased one leg peak by 7% whereas peak remained the
same. The [La] vs. relationships were similar to those reported in
unacclimatized lowlanders. There was a shift to the right upon AN and
[La]peak was reduced by 7% for one leg and by 8% for two leg
exercise. [epi] and [La] were tightly related (mean r=0.81)
independently of FiO2. Thus, normoxia attenuated the increment in
both [La] and [epi] as a function of while the correlation between
[La] end [epi] was unaffected. These data suggest loose linkage of
glycolysis to oxidative phosphorylation under influence from [epi].
In conclusion, high altitude natives appear not fundamentally
different from lowlanders with regard to the effect of acute changes
in FiO2 on [La] during exercise.
Received 12 March 1996; accepted in final form 23 July 1996.
APS Manuscript Number A237-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996