Journal of Applied Physiology, Vol 60, Issue 4 1203-1208, Copyright © 1986 by American Physiological Society
Time course of muscular blood metabolites during forearm rhythmic exercise in hypoxia
J. Raynaud, D. Douguet, P. Legros, A. Capderou, B. Raffestin and J. Durand
O2 concentration, PO2, PCO2, pH, osmolarity, lactate (LA), and hemoglobin
(Hb) concentrations in deep forearm venous blood were repeatedly measured
during submaximal exercise of forearm muscles. Concentrations of arterial
blood gases were determined at rest and during exercise. Experiments were
conducted under normoxia and hypobaric hypoxia (PB = 465 Torr). In arterial
blood, data obtained during exercise were the same as those obtained during
rest under either normoxia or hypoxia. In venous muscular blood, PO2 and O2
concentration were lower at rest and during exercise in hypoxia. The
muscular arteriovenous O2 difference during exercise in hypoxia was
increased by no more than 10% compared with normoxia, which implied that
muscular blood flow during exercise also increased by the same percentage,
if we assume that exercise O2 consumption was not affected by hypoxia.
Despite increased [LA], the magnitude of changes in PCO2 and pH in hypoxia
were smaller than in normoxia during exercise and recovery; this finding is
probably due to the increased blood buffer value induced by the greater
amount of reduced Hb in hypoxia. Hence all the changes occurring in hypoxia
showed that local metabolism was less affected than we expected from the
decrease in arterial PO2. The rise in [Hb] that occurred during exercise
was lower in hypoxia. Possible underlying mechanisms of the [Hb] rise
during exercise are discussed.
