General Obstetrics and Gynecology Obstetrics
Plasma adenosine levels increase in women with normal pregnancies,☆☆

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Abstract

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.)

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Patients and methods

Patients were recruited from the Obstetrics Outpatient Department of the Nippon Medical School Hospital. The criteria for eligibility were as follows: (1) a woman in the third trimester of normal pregnancy, (2) well-established gestational age corroborated by ultrasonography before 20 weeks’ gestation, (3) a singleton fetus, (4) no fetal anatomic anomaly, (5) nonsmoker, (6) normal response to glucose tolerance testing, (7) no evidence of recent infection (eg, rubella, toxoplasma, hepatitis B

Results

As shown in Fig 1, plasma adenosine levels averaged 0.18 ± 0.08 μmol/L in nonpregnant women and 0.59 ± 0.08 μmol/L in normal pregnant women.

. Maternal plasma in nonpregnant women (n = 34) and women with normal pregnancies (n = 34). Vertical long and short bars, Mean and SEM, respectively. ADO, Plasma adenosine concentration in micromoles per liter. Wilcoxon test was used to determine significance of difference between nonpregnant and pregnant women. Level of significance of difference, P < .05.

Comment

In this study a pronounced elevation of maternal plasma adenosine level was found in the third trimester of normal pregnancy. The elevation was accompanied by evidence of platelet activation, strongly suggesting that platelets contribute significantly to the increased adenosine levels. The results also showed an increase of plasma 5′-nucleotidase activity, pointing to more rapid breakdown of adenosine precursors. To the best of our knowledge, this is the first report regarding plasma levels of

Acknowledgements

We thank Dr Hideki Konishi for his excellent suggestions and Christian Hunter for aid in preparing the manuscript.

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Supported by Grants-in-Aid (Nos. 40089175, 00201096, and 30267174) from the Ministry of Education, Science, and Culture and a grant from the Japan Association of Obstetricians and Gynecologists Ogyaa Donation Foundation.

☆☆

Reprint requests: Yoshio Yoneyama, MD, Nippon Medical School, Department of Obstetrics and Gynecology, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan.

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