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Abstract
The effects of detergent sclerosants, sodium tetradecyl sulphate (STS) and polidocanol (POL), on coagulation, antithrombotic and fibrinolytic mechanisms were investigated in vitro.
All samples were spiked with each sclerosant at therapeutic concentrations. Coagulation was investigated in clotting tests and functional assays for clotting factors in plasma. Fibrinogen was measured by the Clauss method and factor (F) XIII by ELISA. At low concentrations, sclerosants shortened phospholipid-dependent clotting times. At high concentrations, STS prolonged all clotting times and destroyed fibrinogen, FV, FVII, FX and FXIII.
Lytic activity in whole blood (WB), albumin and saline was investigated by absorbance densitometry. Both agents induced haemolysis, platelet, platelet microparticle (PMP) and endothelial lysis at high concentrations. The lytic effect was neutralised by albumin and plasma proteins.
Antithrombotic mechanisms were investigated in functional assays for activated protein C (APC), PC, protein S, antithrombin and FXa in normal plasma (NP). High concentration STS demonstrated anti-IIa, anti-Xa and anti-Va activity and potentiated the anticoagulant effects of APC. POL induced APC resistance.
Fibrinolytic enzymes/inhibitors were measured by ELISA in WB and plasma, and plasminogen by a chromogenic assay in NP. Inhibitors of fibrinolysis were elevated at low concentrations of sclerosants. Fibrinolytic enzymes/inhibitors were destroyed by high concentration STS.
Clot formation was assessed by thromboelasotometry in WB. Both agents induced strong clots at low concentrations, weak clots at mid-range and prevented clot formation at high concentrations. In turbidity measurements, neither agent had a lytic effect on cross-linked fibrin but STS destroyed non-cross-linked fibrin.
Platelet and PMP counts were assessed by flow cytometry and platelet activation by ELISA for soluble markers and by flow cytometry for CD62p, CD63 and calcium. Platelet aggregation was assessed by light transmission and impedance aggregometry, and by flow cytometry for glycoprotein (GP)IIb/IIIa. At low concentrations, both agents induced platelet activation, released phosphatidylserine+ PMPs but inhibited aggregation by suppressing the activation of GPIIb/IIIa.
In conclusion, detergent sclerosants interfered with coagulation, antithrombotic and fibrinolytic mechanisms. Both agents activated platelets, released procoagulant PMPs and potentiated prothrombotic and antifibrinolytic mechanisms at low concentrations. At high concentrations, both agents prevented clot formation. High concentration STS exhibited more anticoagulant activity than POL.