Prolonged diving and recovery in the freshwater turtle, Pseudemys scripta—IV. Effects of profound acidosis on O 2 consumption in turtle vs rat (mammalian) brain and heart slices

Abstract

1. 1. The oxygen consumption of rat versus turtle brain and heart slices was compared as a function of extracellular pH and temperature. 2. 2. At pH = 6.20 rat (mammalian) brain and heart slices show a significant depression of oxygen consumption as compared to pH = 7.50 at temperatures of both 24° and 37°C. 3. 3. In the turtle oxygen consumption in brain and heart slices was not depressed at pH = 6.20 compared to pH = 7.50 at 24°C and brain oxygen consumption was not significantly different at the two pH values at 37°C. 4. 4. Turtle heart Q̇ O2 was depressed at 37°C. 5. 5. The results suggests that extracellular acidosis depresses mitochondrial O 2 uptake in mammalian brain and heart, playing a role in the bioenergetic manifestations of O 2 depletion. 6. 6. Turtle brain mitochondria do not show a depression of Q̇ O2 at the acidotic pH. 7. 7. The resistance to acidosis of turtle brain mitochondria presumably enhances the possibility of survival following prolonged diving by maintaining ATP generation during the early diving period and during recovery.