Changes in fetal plasma adenosine and xanthine concentrations during fetalasphyxia with maternal oxygen administration in ewes.

In this study, we measured fetal plasma adenosine and xanthine concentratio ns during and after severe asphyxia, and investigated the key issues relate d to oxygen therapy. Asphyxia was induced by occluding the umbilical cord f or 5 minutes in 6 fetal sheep with and without the administration of oxygen to the ewe. Plasma adenosine concentration increased significantly during cord occlusion in the all fetuses, and the differences between the values i n the fetuses with and without maternal oxygen administration was not signi ficant. By 30 minutes after cord release, plasma adenosine concentration in all fetuses had returned to levels similar to those at the start of the ex periment. Plasma xanthine concentration also increased during cord occlusio n in all fetuses. However, 30 minutes after cord release, plasma xanthine c oncentration had decreased significantly in fetuses without additional oxyg en, while it did not change significantly in fetuses with maternal oxygen a dministration. Thus, we speculated that maternal oxygen administration befo re fetal asphyxia map not contribute to additional ATP stores in fetal orga ns and may produce oxygen free radicals following asphyxia. (C) 2000 Tohoku University Medical Press.