Cerebral excitatory amino acids and Na⁺, K⁺‐ATPase activity during resuscitation of severely hypoxic newborn piglets

Abstract

excitatory amino acids and Na þ ,K þ -ATPase activity during resuscitation of severely hypoxic newborn piglets. Acta Paediatr 1998; 87: 889-95. Stockholm. ISSN 0803-5253 We tested the hypothesis that early brain recovery in hypoxic newborn piglets is improved by resuscitating with an O 2 supply close to the minimum level required by the newborn piglet brain. Severely hypoxic 2-5-d-old anaesthetized piglets were randomly divided into three resuscitation groups: hypoxaemic (n ¼ 8), 21% O 2 (n ¼ 8), and 100% O 2 groups (n ¼ 8). The hypoxaemic group was mechanically ventilated with 12-18% O 2 adjusted to achieve a cerebral venous O 2 saturation of 17-23% (baseline; 45 Ϯ 1%, mean Ϯ SEM). During the 2 h resuscitation period, extracellular aspartate and glutamate concentrations in the cerebral striatum were higher during hypoxaemic resuscitation (p ¼ 0:044 and p ¼ 0:055, respectively) than during resuscitation with 21% O 2 or 100% O 2 , suggesting an unfavourable accumulation of potent excitotoxins during hypoxaemic resuscitation. The cell membrane Na þ ,K þ -ATPase activity of cerebral cortical tissue after 2 h resuscitation was similar in the three groups ( p ¼ 0:30). In conclusion, hypoxaemic resuscitation did not normalize early cerebral metabolic recovery as efficiently as resuscitation with 21% O 2 or 100% O 2 . Resuscitation with 21% O 2 was as efficient as resuscitation with 100% O 2 in this newborn piglet hypoxia model. ٖ Asphyxia, hypoxanthine, in vivo microdialysis, oxygen, reoxygenation BA Feet,