METABOLISM AND FUNCTION IN THE CEREBRAL CORTEX UNDER LOCAL PERFUSION, WITH THE AID OF AN OXYGEN CATHODE FOR SURFACE MEASUREMENT OF CORTICAL OXYGEN CONSUMPTION

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Abstract
In combination with an occlusion-type oxygen cathode the local surface oxygen consumption in a few mm. of cortex can be measured under the influence of any chosen chemical environment. This is done by observing the rate of fall of cortical oxygen tension underneath the tip of an oxygen cathode, following local occlusion of the circulation caused by increased pressure of the electrode. By comparing the local DC potential of the perfused region with that of the surrounding normal cortex, a type of demarcation potential for cerebral cortex can be observed. The estimated value of local surface oxygen consumption of the suprasylvian gyrus of cat cerebral cortex by this method is 4.20 cc per 100 cc wet vol. per min. when perfused with normal Krebs-gelatine solutions, or 6.29 cc per 100 cc wet volume/ minute when the circulation is intact. Cortical surface oxygen consumption increases with local electric stimulation, and reaches a near-saturation level 87% above the resting perfused value at a stimulus frequency of 9-10/sec.