Journal of Applied Physiology, Vol 42, Issue 1 39-43, Copyright © 1977 by American Physiological Society
Arterial lactate responses in dogs made apneic or breathing nitrogen
S. M. Cain
O2 stores are kept more intact in apnea than in N2 breathing which removes
O2stores from the body. If lactate moves readily into the circulation,
arterial lactate should rise sooner with N2 breathing than with apnea
because tissue O2 is lowered faster. This was tested in 10 anesthetized,
paralyzed dogs made hypoxic both ways. Arterial and mixed venous blood were
sampled every minute until circulation began to fail. Calculated changes in
O2 stores would have supported control V O2 for 1.3 min with N2 and 2.7 min
with apnea. The PVO2 at those times were 23.1 and 20.1 Torr. Although
arterial lactate rose sooner with N2 than with apnea, the mean values for
lactate increase for both N2 and apnea were fitted by a single curvilinear
relation with PVO2. The PVO2 at which lactate first rosores were depleted.
Latent period for lactate rise, therefore, was nearly the same as that for
development of tissue hypoxia.
