van Cappellen A M, Heerschap A, Nijhuis J G, Oeseburg B, Jongsma H W
Department of Obstetrics and Gynecology, Faculty of Medical Sciences, University of Nijmegen, The Netherlands.
Am J Obstet Gynecol. 1999 Dec;181(6):1537-45. doi: 10.1016/s0002-9378(99)70401-1.
The relationship among decreased fetal arterial oxygen saturation, the subsequent systemic metabolic acidosis, and changes in cerebral metabolite concentrations in the fetal lamb brain was investigated by means of quantitative proton magnetic resonance spectroscopy.
Fetal hypoxia was induced in 6 fetal lambs by gradual reduction of the oxygen supply to the anesthetized pregnant ewe. In vivo proton magnetic resonance spectroscopy was performed on the fetal lamb brain simultaneously with repeated measurements of fetal arterial oxygen saturation and acid-base balance.
Proton magnetic resonance spectra showed metabolites such as inositol, choline compounds, creatine, and N-acetylaspartate. A signal for cerebral lactate was below the detection level under normoxic conditions and increased during hypoxia to indicate concentrations varying from 2.8 to 11.1 mmol/kg wet weight brain tissue. N -Acetylaspartate signals decreased during hypoxia, whereas signals of inositol, choline compounds, and creatine remained constant.
These results support the view that fetal cerebral anaerobic metabolism in fetal lambs does not start under hypoxic conditions if the arterial blood pH is >7.28 or the base excess is >-8 mmol/L.
通过定量质子磁共振波谱法研究胎羊大脑中胎儿动脉血氧饱和度降低、随后的全身代谢性酸中毒与脑代谢物浓度变化之间的关系。
通过逐渐减少对麻醉的怀孕母羊的氧气供应，在6只胎羊中诱导胎儿缺氧。在对胎羊大脑进行体内质子磁共振波谱分析的同时，反复测量胎儿动脉血氧饱和度和酸碱平衡。
质子磁共振波谱显示了肌醇、胆碱化合物、肌酸和N-乙酰天门冬氨酸等代谢物。在常氧条件下，脑乳酸信号低于检测水平，在缺氧期间增加，表明浓度在2.8至11.1 mmol/kg湿重脑组织之间变化。缺氧期间N-乙酰天门冬氨酸信号降低，而肌醇、胆碱化合物和肌酸的信号保持不变。
这些结果支持以下观点：如果动脉血pH值>7.28或碱剩余>-8 mmol/L，胎羊在缺氧条件下不会开始胎儿脑无氧代谢。
