Effect of acute hypoxia on the enzymes involved in the metabolic and nervous functioning of rat brain.

Rats were exposed to a simulated altitude of 25,000 ft for 4 h in a decompression chamber, and the activity of some tissue enzymes estimated. Succinate dehydrogenase activity was significantly decreased and cholinesterase activity significantly elevated in the brain homogenates of the hypoxic rats, succinic dehydrogenase activity was significantly increased. There was no change in the activity of Mg+2-ATPase and Na+-K+-ATPase in the microsomal fractions of liver or brain homogenates of the hypoxic animals.