[Possible role of serotonin in hemostatic the mechanism of action of desmopressin (DDAVP) in patients with uremia].

Haemorrhagic diathesis is a serious complication of uraemia. Desmopressin is known to shorten prolonged bleeding time in uraemia but mechanism of the haemostatic action of this drug remains still unknown. The aim of the work was to study the effect of desmopressin on some haemostatic parameters in relation to plasma and platelet serotonin. Desmopressin was administered i.v. to 33 haemodialysed patients (age range 27-66 years) in a dose of 0.4 microgram/kg b.w., 90 minutes after desmopressin infusion bleeding time became significantly shorter (p < 0.001) and correlated with the shortening of the euglobulin clot lysis time (r = -0.43, p < 0.05). Tissue plasminogen activator activity increased (p < 0.01) and its inhibitor (PAI) activity decreased (p < 0.001) after desmopressin infusion. A correlation between the fall in platelet serotonin content and changes in tissue plasminogen activator and PAI activities was found (r = 0.55, p < 0.01 respectively). A rise in plasma serotonin concentration was observed. In vitro desmopressin inhibited 14C serotonin uptake in a dose-dependent manner. After 2 hours of platelet incubation with desmopressin in a concentration of 4 ng/ml 16% of 14C serotonin was released. A possibility of serotoninergic mechanism in the haemostatic action of desmopressin is suggested.