Dynamic changes in glucose and lactate in the cortex of the freely moving rat monitored using microdialysis

These experiments for the first time examine simultaneous changes in glucos e and lactate in unanaesthetised animals during moderate hypoxia. Unanaesth etised rats were exposed to moderate hypoxia for a period of 15 min by redu cing inspired oxygen to 8%. Changes in glucose and lactate were monitored i n rat cortex using microdialysis and a novel dual enzyme-based assay. Sampl es of dialysate collected at 3-min intervals were assayed for both glucose and lactate. There was an early rapid rise of lactate that reached a peak a t the end of the period of hypoxia followed by a steep decline. Glucose sho wed a very much smaller delayed increase that started during the period of hypoxia and continued beyond it. The origin of the rise in glucose is discu ssed, using the temporal relationship between the lactate and glucose chang es.