A MODEL FOR DETECTING EARLY METABOLIC CHANGES IN NEONATAL ASPHYXIA BY1H-MRS

In newborn rabbits, the early cerebral metabolic changes caused by hyp oxic-ischemic (H-I) insult was examined by using volume localized 1H-M RS (STEAM). Partial ischemia was caused by unilateral carotid artery L igation, and hypoxia was induced by 10% oxygen inspiration for 150 min utes. Lactate immediately increased after hypoxia induction and almost disappeared 120 to 150 minutes after removal of hypoxia in both H-I a nd hypoxia-only experiments. Lactate production correlated well with d ecrease of the blood oxygen saturation. More lactate was produced on i schemic side 50 minutes post-hypoxia induction in H-I study. Ischemia alone did not cause any significant lactate production, Lactate caused by hypoxia can be dynamically monitored by localized 1H-MRS. Existenc e of regional ischemia can induce greater anaerobic glycolysis and may affect the pattern of brain injury under hypoxia. 1H-MRS is a sensiti ve tool to detect the acute metabolic changes caused by H-I insult.