CHEMICAL CHANGES IN THE BRAIN PRODUCED BY INJURY AND BY ANOXIA

Abstract

In a total of 26 animals the cerebral cortex has been analyzed, after freezing in situ with liquid air, for the following constituents: lactic acid, inorganic phosphate, phosphocreatine, pyrophosphate and "hexose phosphates." The analyses were done when the electrical activity or the pH of the cortex indicated that significant chemical changes might be expected. It was found that injury or removal of one area of the cerebral cortex could produce marked chemical changes in adjacent and even in remote areas; that the concs. of lactic acid and of inorganic phosphate are increased and that of phosphocreatine is decreased in conditions of anoxia resulting from breathing N or from reduction of cerebral blood flow; that the electrical activity disappears while the cortex is shifting in an alkaline direction in anoxic anoxia and disappears while the cortex is shifting in an acid direction in stagnant anoxia; that the electrical activity of the cortex is obliterated in conditions of anoxia before any detectable changes in the levels of adenylpyrophosphate or "hexose phosphates" take place; that during recovery from anoxic anoxia, lactic acid promptly decreases to its normal level in the brain and phosphocreatine is apparently resynthesized, while the concs. of inorganic phosphate and phosphocreatine tend to "overshoot" their original values when the electrical activity is showing a rebound.