Molecular mechanisms of hemostatic efficiency of etamzilat after contact ureterolithotripsy

Abstract

Understanding the key mechanisms regulating platelet compensatory responses facilitates the development of modern hemostatic therapeutic agents. Aim of the study was to determine the peculiarities of molecular regulation of the proaggregant function of platelets (Ps) during administration of etamsylate (ETZL) to patients with macrohematuria after contact urethrolithotripsy. Methods. The study included 42 patients (20 men and 22 women; mean age 52.9±1.4 years; 19-79 years) who had macrohematuria within 6 h after contact urethrolithotripsy (CLT) and were treated with ETZL (single dose -250 mg). The cohort of patients was divided into two groups: with effective - Group 1 (20 patients) and ineffective hemostasis - Group 2 (22 patients). The activity of purine PX1- and P2Y-receptors, adenosine A2A-receptor, α2-adrenoreceptor, TR-receptor to TxA2, GPVI-receptor and PAF-receptor was investigated at EC50 concentrations. The proaggregant effect of ETZL was assessed by incubating c with 10 μM of the drug. Modeling of receptor interactions was reproduced by incubating Ps with subthreshold concentrations of agonists (EC10). Platelet aggregation was assessed by the turbidimetric method on a ChronoLog analyzer (USA). Statistical analysis was performed using the MedCalc package. Results. At 6h after the introduction of ETZL, macrohematuria decreased (p<0.05) in Group 1 patients, and did not change in Group 2. Group 1 showed hyperreactivity of P2X1-receptor, α2-adrenoreceptor, normoreactivity of TP-receptor, P2Y-receptors and hyporeactivity of PAF-receptor and GP VI-receptor to collagen; adenosine A2-receptor.In Group 2, hyperreactivity of adenosine A2A-receptor, α2-adrenoreceptor, normoreactivity of P2X1-receptor and hyporeactivity of P2Y-receptor, TR-receptor, PAF-receptor, GP VI-receptor were found. An in vitro study confirmed that ETZL modulated the activity of P2X1-receptor, α2-adrenoreceptor, and TP-receptor in effective hemostasis, and α2-adrenoreceptor, P2X1-receptor, and P2Y-receptor activity in ineffective hemostasis.  The maximal aggregation effect was reproduced in Group 1 when Ps was incubated with ETZL and ATP, and in Group 2 when incubated with ETZL and adrenaline. Conclusion. The hemostatic efficacy of ETZL after contact ureterolithotripsy is determined by the cluster and activity of receptors regulating Ps aggregation.