文本框: CEREBRAL INTRACELLULAR CALCIUM CONCENTRATION IN ASPHYXIATED RAT FETUSES RESUSCITATED WITH OXYGEN Nong S-H, Xie Y-M, Huang X-S Department of Neonatal Medicine, Guangdong Provincial People's Hospital, Guangzhou, China Objective: To investigate the effects of resuscitation using oxygen of three concentrations on changes of cerebral intra- and extra-cellular calcium, sodium and potassium in asphyxiated rat fetuses. Methods: Fifty-six fetal rats of twenty-day gestational age were randomly divided into five groups: sham operation (control, n=11), room-air resuscitation (n=10), and oxygen-resuscitated group A, B, C (n=14, 11, and 10 respectively) of different oxygen-inhaled concentrations and different oxygen timings. Fetal rats in the latter four groups suffered from ischemia and hypoxia in-utero resulting from interruption of placental circulation. After re-circulation, intra- and extra-cellular concentrations of calcium, sodium, and potassium in the brains were measured for each group. Results: Intracellular free calcium concentration of fetal rat brains was similar between the room-air resuscitation group (552.08±93.50 nmol/L) and the oxygen-resuscitated group A (520.61±79.08 nmol/L, oxygen-inhaled concentration was 92.8%), and both were significantly higher than that in the control (315.27±86.88 nmol/L) (P<0.001). After resuscitation with 65% oxygen, no matter whether it started before (group B) or at the beginning of hypoxia (group C), their intracellular free calcium concentrations (441.46±47.93 and 452.93±36.38nmol/L respectively) were significantly lower than those in the room-air resuscitation group (P<0.01) and group A (P<0.05), though still higher than those in the control. There was generally no difference in the total concentrations of calcium, sodium, or potassium among all groups. Conclusion: Resuscitation with oxygen of different concentrations might produce different results. ① Resuscitation with 92.8% oxygen or room air had a similar effect on the parameters measured, indicating that resuscitation of asphyxiated neonates using pure oxygen might not be superior to that using room air; ② With lower cerebral intracellular calcium concentrations, resuscitation with 65% oxygen might produce a better outcome compared with that using pure oxygen or room air. 0681