Effects of ATP, ADP, thrombin, vasopressin and U46619 on human placental nitric oxide synthase activity

Abstract

The human placenta contains nitric oxide synthase (NOS) activity, which had been previously found to be localized in the syncytiotrophoblast and the endothelial cells of stem villous vessels. Nitric oxide produced by the syncytiotrophoblast could affect maternal platelet aggregation. The aim of the present study was to examine the effects of substances known to cause platelet aggregation (arginine vasopressin (AVP), the thrombaxane A2 mimetic U46619, adenosine diphosphate (ADP) and thrombin) on NOS activity of human placental explants in vitro. Placentae were obtained at term from women with obstetrically uncomplicated deliveries. NOS activity was measured in explants by determining the conv..