The possible role of hydrogen sulfide as a modulator of hemostatic parameters of plasma.

Hydrogen sulfide (H2S) is a well known toxic gas at high levels. However, at physiological levels, H2S may play a role in the pathogenesis of various cardiovascular diseases. The objective was to study the effects of exogenous H2S on the hemostatic parameters (coagulation and fibrinolytic activity) of human plasma. Human plasma was incubated (5, 15 and 30 min) with NaHS as a H2S donor at the final concentration of 0.01-100 μM. Hemostatic factors, such as maximum velocity of clot formation, fibrin lysis half-time, the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) were estimated. Moreover, the aim of our study was to establish the influence of NaHS (10 μM; 5, 15 and 30 min) on the clot formation using the purified fibrinogen. We demonstrated that coagulation/fibrinolytic properties of human plasma incubated with NaHS were changed. APPT, PT and TT of plasma treated with NaHS at tested concentrations--0.01-100 μM were prolonged. We observed that NaHS (0.01-100 μM) reduced fibrin polymerization in whole plasma and 10 μM NaHS also reduced polymerization of purified fibrinogen. In the presence of NaHS (at the low tested concentration--1 μM) the decrease was about 18% (in plasma, p<0.05). Our experiments also showed that NaHS (0.01-100 μM) stimulated the fibrin lysis in whole plasma. However, the time-dependent (5, 15 and 30 min) reduction of fibrin/fibrinogen polymerization and stimulation of fibrin lysis by NaHS (10 μM) was not observed. In conclusion, the present study demonstrates the anticoagulant properties of exogenous H2S in vitro.