Prolonged diving and recovery in the freshwater turtle, Pseudemys scripta—III. The effect of acidosis on lactate generation and O 2 consumption in brain slices

Abstract

1. 1. The effect of progressive extracellular acidosis on the rate of lactate generation ( Q lactate) and O 2 consumption ( Q O 2 ) was studied in brain slices obtained from the freshwater turtle Pseudemys scripta elegans. 2. 2. At the nadir pH found in vivo during diving, Q lactate is 60% of the value found at pH 7.5 and at an extracellular pH 6.0, the value is 37% of the value at pH 7.5. These findings suggest that ATP supply derived from glycolysis decreases progressively during prolonged diving and that bioenergetic failure is an important factor during this process. 3. 3. Total brain Q o 2 does not change significantly over a range pH 6.0–7.5, averaging 2.3 ± 0.35μM × 100 g tissue −1 × hr −1. This suggests that the failure to repay the apparent O 2 deficit accrued during prolonged diving is not pH mediated.