Inhibitory effect of rhynchophylline on platelet aggregation and thrombosis.

Rhynchophylline (Rhy) inhibited rabbit platelet aggregation induced by arachidonic acid (AA), collagen, and ADP. The values of IC50 were 0.72, 0.74, and 0.67 mmol.L-1, respectively. Rhy reduced the thromboxane B2 (TXB2) generation in PRP induced by collagen but failed to reduce that induced by AA. Rhy suppressed malondialdehyde (MDA) formation in platelet suspension stimulated by thrombin, inhibited the platelet factor 4 (PF4) release. It did not alter intraplatelet cAMP concentration. Rhy 10-20 mg.kg-1 iv showed a significant inhibition of venous thrombosis and cerebral thrombosis in rats.