ADPase activity in human maternal and cord blood: possible evidence for a placenta-specific vascular protective mechanism

ADPase enzyme activity was assessed in maternal and cord plasma by adding radio-labelled ADP and quantitating the degradation products. Cord plasma had sufficiently greater ADPase activity than the corresponding maternal plasma obtained ante- and post-partum. Thus, residual radiolabelled ADP was 30, 32 and 17% of total radioactivity after 30 min incubation (37°C) in maternal ante-partum, maternal post-partum and cord plasmas, respectively. ADPase may act as a platelet aggregation inhibitor in the placental and fetal circulation.