Oxidative metabolism in cerebral ischemia. Part 1. Measurement of oxygen extraction slopes of grey and white matter in vivo.

Regional oxidative metabolism was studied in vivo. Oxygen availability was monitored from polarographic electrodes in frontal cortical and subcortical tissue. The rate of oxygen extraction in these regions was estimated at frequencies of up to 3 measurements per minute. Transient ischemia of the frontal regions was induced and the resultant decay in the oxygen trace was analyzed kinetically. The oxygen extraction slopes (OES) were steeper in grey than in white matter. They were relatively insensitive to alterations of arterial blood gas concentrations within the physiological range. The slopes were predictably influenced by pharmacologic agents known to alter the rate of oxidative metabolism. Artifacts which may interfere with the OES measurments were considered. This method of estimating regional tissue oxygen extraction may be appropriate for studying aspects of focal CI.