Lactate production in isolated perfused rat lung.

The ability of the isolated perfused rat lung to produce lactate under aerobic and hypoxic conditions has been studied. The lung has been found capable of producing lactate at a rate of 53 mumol/g dry wt per h in the presence of as great as 1 mM extracellular lactate under aerobic conditions. Essentially 100% of the lactate synthesized was derived from [U-14C]glucose. When hypoxic, the rate of lactate production doubled, but only 60% was found to be derived from [U-14C]glucose. When the perfused lung was exposed to aerobic conditions following hypoxia, it was found that lactate production did not decrease. However, lactate production from [U-14C]glucose did increase. It is concluded that lung tissue possesses a high rate of lactate production under aerobic contitions from glucose in comparison to glucose oxidation to CO2. When the lung is hypoxic, lactate production increases as a probable result of amino acid catabolism with little anaerobic energy production occurring. The effect of hypoxia was not reversed within the duration of the performed experiments.