Abstract-F 2 -isoprostanes are prostaglandin (PG) isomers produced in vivo through free radical-catalyzed peroxidation of arachidonic acid, which may affect platelet function. The current study investigated the effects of 8-epiprostaglandin F 2␣

SummaryWe studied in vitro the antiplatelet activity of a new nitroderivative chemically related to acetylsalicylic acid: 2 acetoxybenzoate 2-[l-nitroxy-methyl]-phenyl ester (NCX 4016), in order to identify any effects due to the release of nitric oxide and the blockade of cyclooxygenaseThe effects of scalar doses of NCX 4016 on the early phase of platelet activation, platelet aggregation and thromboxane A2 production were investigated. We observed inhibitory effects of NCX 4016 on platelet adhesion (IC50 = 7.3 × 10−5 M), platelet cytosolic calcium concentration, assayed by fluorescent probe Fura 2, and the expression of glycoprotein IMIIa (CD41 / αIIbβ3) (IC50 = 3.4 × 10−5 M) and P-selec-tin (CD62 / GMP-140) (IC50 = 4.9 × 10−5 M) measured by flow cytometry. NCX 4016 also prevented thrombin-induced platelet aggregation (IC50 = 3.9 × 10−5 M). None of these parameters were affected by acetylsalicylic acid. These inhibitory activities of NCX 4016 were abolished by oxyhaemoglobin and methylene blue. Intracellular cyclic GMP observed during thrombin-induced aggregation was increased by incubation with NCX 4016. These results appear to be attributable to the release of nitric oxide, which activates soluble platelet guanylyl-cyclase and promotes intracellular cyclic GMP increase. NCX 4016 almost completely inhibited platelet thromboxane A2 production and arachidonic acid-induced platelet aggregation. This also occurred in the presence of oxyhaemoglobin and methylene blue, indicating that its antiplatelet activity can be attributed not only to nitric oxide release but also to cyclo-oxygenase inhibition.

Increased intestinal permeability and abnormal motility were frequent without evidence of bacterial translocation in cirrhosis even without ascites. They are likely to be facilitators for bacterial translocation and thus precede it.

NCX4016 (2 acetoxy‐benzoate 2‐(2‐nitroxymethyl)‐phenyl ester, NicOx S.A., France) is an anti‐thrombotic agent, chemically related to acetylsalicylic acid (ASA) and able to release NO. We tested the effects of NCX4016 and ASA on the release of the thromboxane (TX) A2 metabolite TXB2, tumour necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6), expression and activity of tissue factor (TF) in stimulated, adherent human monocytes. Both ASA and NCX4016 1 – 1000 μmol l−1 dose‐dependently reduced TXB2 concentration, measured by RIA in the supernatant of 10 μg ml−1 LPS‐stimulated cells. NCX4016 activity was comparable to that of equimolar ASA when incubation lasted 6 h (NCX4016 30 μmol l−1: −86.0±10.1%, NCX4016 300 μmol l−1: −92.2±9.0%, ASA 30 μmol l−1: −92.3±7.5%, ASA 300 μmol l−1: −97.3±1.0%, n=6, M±s.d.). Most of the activity of NCX4016 up to 100 μmol l−1 was prevented by 10 μmol l−1 ODQ, inhibitor of cyclic GMP. NCX4016 100 – 300 μmol l−1 reduced TNF‐α (NCX4016 300 μmol l−1=−77.2±19.9%, n=6) and IL‐6 (NCX4016 300 μmol l−1: −61.9±15.2%, n=6) in LPS stimulated monocytes while ASA had no significant effects. TF activity (NCX4016 300 μmol l−1: 53.7±39.9%, n=4) and immunoreactive TF (NCX4016 300 μmol l−1: −93.9±7.9%, n=7), measured in the supernatant of stimulated cells, were also dose‐dependently inhibited by NCX4016 but not by ASA. The present results indicate that NCX4016 inhibits TXA2 generation as well as cytokine release and TF in human monocytes partly via NO‐dependent mechanisms. NCX4016 may have a favourable profile of activities in the clinical setting of athero‐thrombosis. British Journal of Pharmacology (2001) 134, 905–911; doi:10.1038/sj.bjp.0704326

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