Correlation between levels of plasma adenosine triphosphate and stress to the fetus at delivery.

Adenosine triphosphate (ATP) and its metabolites are released from intracellular stores and levels of ATP in the plasma are affected by hypoxia and by exercise. We examined levels of plasma ATP in the fetus at the time of obstetrical delivery. The arterial (ACB), venous cord (VCB) and maternal venous blood (MVB) samples were collected immediately after clamping of the cord. ATP was determined by the bioluminescence method. The levels of plasma ATP were significantly higher in ACB than in VCB or in MVB. There were significant correlations between the levels of ATP in ACB and in VCB, between the levels in ACB and in MVB and between the levels in MVB and in VCB. In case of delivery by elective cesarean section, the levels of ATP in ACB were significantly higher than those in ACB of the fetus delivered vaginally. We found a significant correlation between the levels of plasma ATP in ACB and PO2 in VCB, though there was no significant correlation between the levels of ATP and pH and PCO2. These observations suggest that ATP in ACB may be of fetal origin, that the levels decrease concomitantly in response to stress during vaginal delivery and correlate with the oxygen supplied from the placenta.