Platelet responsiveness to L-arginine in hypertensive disorders of pregnancy.
OBJECTIVE
In chronically hypertensive (CH), preeclamptic (PE), and normotensive pregnant women (N), we investigated ex vivo platelet aggregation in response to L-arginine (L-Arg) and sodium nitroprusside (SN), which are respectively the substrate and donor of nitric oxide (NO).


METHODS
Platelet aggregation was determined with a dual-channel aggregometer by measuring transmittance of light through the sample in comparison to platelet poor plasma, as a reference. Aggregation induced by adenosine diphosphate was continuously recorded for 3 min and measured before and after preincubation with L-Arg and SN.


RESULTS
Preincubation with L-Arg significantly reduced platelet aggregation in N and CH patients (p < 0.05) but not in PE women. Preincubation with SN affected aggregation in PE women also (p < 0.001). No correlation was found between platelet response to L-Arg or SN stimuli and the severity of hypertensive disorders expressed as week of gestation at delivery or birth weight.


CONCLUSIONS
The present study demonstrates that a decreased platelet sensitivity to L-Arg characterizes PE women, whereas SN maintains its antithrombotic power. This impairment seems to be specific for PE, because platelets of CH patients utilize L-Arg normally. This finding supports the involvement of the L-Arg-NO pathway in the pathogenesis of the procoagulative features of PE and probably in the onset of the disease. The maintained response to SN in PE patients suggests a possible therapeutical use of NO donors in the disease.
Neri
I
I
Departments of Obstetrics and Gynecology, University of Modena, Modena, Italy. facchi@unimo.it
Piccinini
F
F
Marietta
M
M
Facchinetti
F
F
Volpe
A
A
D000328:Adult; D000704:Analysis of Variance; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001120:Arginine / Q000494:pharmacology*; D001724:Birth Weight; D001794:Blood Pressure; D016022:Case-Control Studies; D002585:Cesarean Section / Q000706:statistics & numerical data; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D006152:Cyclic GMP / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D006801:Humans; D006973:Hypertension / Q000209:etiology / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects*; D011225:Pre-Eclampsia / Q000209:etiology / Q000378:metabolism*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000209:etiology / Q000378:metabolism*; D018709:Statistics, Nonparametric
D000959:Antihypertensive Agents; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D001120:Arginine; D006152:Cyclic GMP