Relationship between serum 5′-nucleotide phosphodiesterase activity and thrombophilia: enzyme activity in fetus and in patients with acute coronary syndrome

Abstract

Inhibition of ADP-induced platelet aggregation by a placental substance was first reported by Myatt et al. in 1977 [1]. This substance was assumed to play an important role in maintaining fetal–placental circulation under extremely low oxygen pressure. However, the principle behind this activity has not been fully characterized as yet. Hutton et al. [2] reported in 1980 that this activity was derived from placental heat stable alkaline phosphatase. Sakura et al. [3] proposed that placental 5Vnucleotide phosphodiesterase (PDEase) is involved in the inhibition of the platelet aggregation mentioned above. 5V-Nucleotide phosphodiesterase is an ectoenzyme, and hydrolyzes phosphodiester bonds of DNA and RNA releasing nucleoside 5V-monophosphate. This enzyme also hydrolyzes pyrophosphate bond of ATP, ADP and NAD [4,5]. Enzyme activity in serum is elevated in hepatic disease [6,7]. The physiological function of the enzyme in umbilical cord serum remains to be clarified. We have shown that the enzyme purified from human umbilical cord serum hydrolyzed ADP and suppressed ADP-induced platelet aggregation depending on the enzyme concentration in platelet-rich plasma [8]. These data suggest that serum PDEase is a potent inhibitor of platelet aggregation. In neonates and infants, thromboembolic events have been shown to be rare, possibly due to low vitamin K-dependent coagulation factors and poor ATP storage in neonate platelet [9–12]. Serum PDEase