Cerebral free energy and viability: ATP in rats under nitrogen and iodoacetate with the effects of temperature

Abstract

The survival times and the cerebral ATP concentrations during anoxia have been determined. Rats were subjected to anoxia for a measured time, returned to air and survival determined. For ATP determinations, rats were frozen in liquid nitrogen following the anoxia, and the brain analyzed by the firefly luminescence method. The survival time (ST₅₀) in anoxia is 63 seconds. During the first 20 seconds, the ATP remains at 2µM/gm; it then falls to 1.0 µM/gm at 65 seconds. When glycolysis is inhibited by sodium iodoacetate the ST₅₀ decreases to 10 seconds; the ATP remains unchanged for 5 seconds and then decreases rapidly (0.14 µM/gm/sec.) to 1.0 µM/gm at 10 sec. Cooling the animal to 25, 20 or 15°C for 10 minutes increases the ST₅₀ and decreases the rate of ATP disappearance. The ATP concentration at the corresponding ST₅₀ increases with decreasing body temperature.