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 act ivation and 5'-nucleotidase as causes of changes in adenosine levels. STUDY DESIGN: We measured plasma adenosine levels, the platelet activation markers beta-thromboglobulin and platelet factor 4, and 5'-nucleotidase act ivity, which catalyzes dephosphorylation from adenosine monophosphate to ad enosine, in 34 nonpregnant women and 34 women with normal pregnancies in th e third trimester. RESULTS: The mean plasma adenosine level in pregnant women was 0.59 +/- 0.0 8 mu mol/L (mean +/- SEM), which was significantly higher than that found i n nonpregnant women (0.18 +/- 0.04 mu mol/L; P<.01). In pregnant women plas ma P-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 dur ing normal pregnancy. This increase may be an endogenous compensatory mecha nism that diminishes platelet activation and maintains vessel integrity dur ing normal pregnancy.