AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 5 651-R657, Copyright © 1983 by American Physiological Society
Metabolic adjustments to diving and recovery in the African lungfish
J. F. Dunn, P. W. Hochachka, W. Davison and M. Guppy
The metabolic potentials of the heart, brain, white muscle, and liver in
the African lungfish were estimated by enzymatic data. Metabolic effects of
a 12-h submergence were monitored using metabolite measurements. Heart was
the most oxidative tissue but also showed the greatest anaerobic potential.
The brain displayed relatively low oxidative capabilities. White muscle
remained almost inert. Although high-energy phosphate concentrations in
brain and heart did not fall during submergence, glycolysis was activated
as indicated by crossover plots, depletion of endogenous glycogen stores,
and lactate accumulation. Blood-tissue lactate and glucose gradients
indicated 1) that the heart and brain released lactate throughout
submergence, 2) that after 12 h of submersion the brain and heart were
probably obtaining all their required glucose from the blood, 3) that the
liver released glucose throughout submergence, and 4) that white muscle was
metabolically isolated from the rest of the body during submergence. It
appeared that perfusion adjustments occurring during submergence were
directed more toward regulating intertissue exchange of metabolites than
toward oxygen conservation. Comparisons are made to diving responses in
mammals.
