Abstract
Platelet activation, including platelet adhesion, platelet aggregation and platelet release reaction, played an important role in thrombogenesis. We all knew that Platelet glycoprotein IIb/IIIa antagonist was the most effective drug for anti-aggregation, while we don’t know clearly its effect on platelet release reaction and the relations between its effects on platelet aggregation and release reaction. Platelet release reactions included α-granules and dense granules releasing. When α-granules were released, its membrane glycoprotein CD62p was expressed in the platelet membrane. We used the CD62p expression as the index of platelet release reaction. In the current study, the 4-peptides RGDS (Arg-Gly-Asp-Ser) was used as glycoprotein IIb/IIIa antagonist. We detected the effects of RGDS on platelet aggregation and CD62p expression induced by adenosine diphosphate (ADP) (finial concentration, 5μmol/L) in vitro. 50, 100, 200, 400 and 800μmol/L RGDS were used separately in the test. RGDS of each concentration could significantly inhibited maximal platelet aggregation (PAG(M)) induced by ADP, the 50% inhibiting concentration was approximately 200μmol/L. 800μmol/L RGDS could inhibited PAG(M) by 80.48±8.18%. Only ≥200μmol/L RGDS could significantly inhibited platelet CD62p expression. 800μmol/L RGDS could inhibit platelet CD62p expression by 27.31±9.74%. The inhibiting effect of RGDS on PAG(M) and platelet CD62p expression had significantly correlation (r =0.976, P<0.05). These results indicated that RGDS in low concentration (<200μmol) had little negative effect on platelet release reaction induced by ATP, while in relatively high concentration (≥200μmol) RGDS could inhibit platelet release reaction. When RGDS concentrations were same its effect on platelet release reaction was much less than that on platelet aggregation, which indicated that platelet glycoprotein IIb/IIIa compound could only partly participated in the platelet release reaction but fully participated in platelet aggregation induced by ADP.
