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, C- 14-labeled lactate was injected into turtles after 2 h of a 6-h submer gence at 20 degrees C. C-14 activities of plasma and chamber water wer e tested at intervals during anoxia and also in expired air during 39 h of recovery. Partitioning of label in major body compartments [extra cellular fluid (ECF), intracellular fluid (ICF), and shell] and C-14 a ctivity and glycogen in selected tissues (heart, liver, and muscle) we re measured after anoxia (n = 7) and after recovery (n = 6). Shell C-1 4 and [lactate] were extensively measured on six anoxic turtles. Durin g anoxia all C-14 remained in the animal indicating no urine productio n. At 6 h of anoxia 47% of recovered C-14, presumably still as lactate , was in the ECF, 27% in the ICF, and 30% in the shell. During recover y, plasma [lactate] fell from 35 to 5 meq, but surrounding water and e xpired air accounted for only 9 and 8%, respectively, of recovered lab el. The ICF portion grew to 41%, associated with a recovery in tissue glycogen. The shell still had 22% of total label. We conclude that, du ring recovery from anoxia, lactate is predominantly resynthesized to g lycogen, and only a small fraction is directly oxidized. During anoxia , however, lactate is widely distributed in the body, and a surprising ly large and functionally significant fraction resides in the shell.