Lactate distribution and metabolism during and after anoxia in the turtle, Chrysemys picta bellii.

To determine the fate of lactate during and after prolonged anoxia, 14C-labeled lactate was injected into turtles after 2 h of a 6-h submergence at 20 degrees C. 14C activities of plasma and chamber water were tested at intervals during anoxia and also in expired air during 39 h of recovery. Partitioning of label in major body compartments [extracellular fluid (ECF), intracellular fluid (ICF), and shell] and 14C activity and glycogen in selected tissues (heart, liver, and muscle) were measured after anoxia (n = 7) and after recovery (n = 6). Shell 14C and [lactate] were extensively measured on six anoxic turtles. During anoxia all 14C remained in the animal indicating no urine production. At 6 h of anoxia 47% of recovered 14C, presumably still as lactate, was in the ECF, 27% in the ICF, and 30% in the shell. During recovery, plasma [lactate] fell from 35 to 5 meq, but surrounding water and expired air accounted for only 9 and 8%, respectively, of recovered label. The ICF portion grew to 41%, associated with a recovery in tissue glycogen. The shell still had 22% of total label. We conclude that, during recovery from anoxia, lactate is predominantly resynthesized to glycogen, and only a small fraction is directly oxidized. During anoxia, however, lactate is widely distributed in the body, and a surprisingly large and functionally significant fraction resides in the shell.