gms | German Medical Science

Introduction: The biological potential of hydrogen sulfide (H₂S) has attracted growing interest in the field of vascular biology. The aim of this study was to analyze the effect of the water-soluble, slow releasing H₂S donor GYY 4137 on microvascular thrombus formation in-vivo and platelet activation in-vitro.

Materials and methods: We used the model of light-dye-induced thrombosis in the dorsal skinfold chamber of male wild-type (n=20) and P-selectin-deficient (n=6) mice. Animals received intravenously either GYY (50mg/kg body weight) or the vehicle solution (30% DMSO; 10ml/kg body weight). Kinetics of thrombus formation in arterioles and venules as well as tail-bleeding-time was assessed. Platelets activated by the thrombin receptor activating peptide (TRAP) were exposed to GYY and studied for expression of P-selectin and GPIIb/IIIa as well as for fibrinogen binding using flowcytometry (n=6-7 independent experiments). Means±SEM. ANOVA followed by post-hoc comparison tests.

Results: GYY reduced the TRAP-induced platelet activation with a fraction of P-selectin expressing platelets of 28±8% (5mM GYY) and 16±4% (10mM GYY; p<0.05 vs untreated TRAP-activated platelets: 90±2%). Concomitantly, the number of GPIIb/IIIa-expressing platelets was found decreased to 61±15% (5mM GYY) and 34±13% (10mM GYY; p<0.05 vs untreated TRAP-activated platelets: 82±20%). In addition, fibrinogen binding of TRAP-activated platelets (mean fluorescence intensity) was also found reduced by GYY (5mM: 50±6 and 10mM: 48±7; p<0.05 vs untreated TRAP-activated platelets: 135±26). In wild-type animals thrombus formation was found significantly delayed by GYY in both arterioles and venules (446±82s; 434±53s p<0.05 vs DMSO: 216±27s; 237±24s), while in P-selectin-deficient mice arteriolar and venular thrombus formation was not delayed by GYY (298±60s; 290±32s; DMSO: 226±30s; 300±48s) In parallel, tail bleeding time was found significantly increased in GYY-treated wild-type mice (184±62s; p<0.05 vs DMSO: 42±9s) compared to P-selectin-deficient mice (GYY: 31±4s; DMSO: 31±4s).

Conclusion: H₂S dose dependently reduces the expression of platelet adhesion molecules. This mechanism, in particular the reduction of P-selectin expression, seems to be reasonable for the anti-thrombotic efficacy of H₂S.