THE EFFECT OF OXYGEN TENSION ON THE METABOLISM OF CEREBRAL CORTEX, MEDULLA AND SPINAL CORD

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Abstract
The rates of O2 uptake of cortex, medulla and spinal cord of the cat in phosphate medium were in the ratio 100:34:12, whereas the ratio for anerobic lactic acid production was 100:17:5. The O2 uptake of all 3 tissues was sensitive to O2 tension. The shape of the O2 uptake-O2 tension curve was essentially the same for the 3 tissues. The anaerobic lactic acid production was twice as great in cortex as in medulla per unit of O2 uptake in O2. Lactic acid production was sensitive to O2 tension in cortex and medulla but not in cord. These differences in lactic acid production are offered in partial explanation for the variations in resistance to anoxia from one region to another within the C. N. S. In cortex, lactic acid production and O2 uptake varied inversely when the O2 tension was altered. In medulla, surprisingly enough, lactic acid production was maximal at 2-3 volumes % O2. The possible relationship of this to a previously described respiratory phenomenon is mentioned.