Plasma adenosine levels increase in women with normal pregnancies,

Objective: The aim of this study was to investigate plasma adenosine levels during normal pregnancy and to evaluate the possible roles of platelet activation and 5′-nucleotidase as causes of changes in adenosine levels. Study Design: We measured plasma adenosine levels, the platelet activation markers β-thromboglobulin and platelet factor 4, and 5′-nucleotidase activity, which catalyzes dephosphorylation from adenosine monophosphate to adenosine, in 34 nonpregnant women and 34 women with normal pregnancies in the third trimester. Results: The mean plasma adenosine level in pregnant women was 0.59 ± 0.08 μmol/L (mean ± SEM), which was significantly higher than that found in nonpregnant women (0.18 ± 0.04 μmol/L; P< .01). In pregnant women plasma β-thromboglobulin levels, platelet factor 4 levels, and 5′-nucleotidase activity were significantly higher than in nonpregnant women (P< .05). Conclusion: The increase of plasma adenosine may be attributed at least in part to platelet activation and an increase of 5′-nucleotidase activity during normal pregnancy. This increase may be an endogenous compensatory mechanism that diminishes platelet activation and maintains vessel integrity during normal pregnancy. (Am J Obstet Gynecol 2000;182:1200-3.)