The effect of a medicinal Chinese herb on platelet function.

We investigated the effect of the Chinese herb Injectio Salvia Miltiorrhizae (ISM) on human platelet function in vitro. ISM inhibited platelet aggregation and serotonin release induced by either ADP or epinephrine in a dose dependent manner. This effect of ISM was observed with both gel-filtered platelets (ID50 = 8-30 micrograms ISM/ml gel-filtered platelets) and platelets in plasma (ID50 = 400-900 micrograms ISM/ml of platelet-rich plasma). The active molecule(s) in ISM was heat stable, resistant to acid, base and proteolysis and fractionated on Sephadex 6-25 at MW approximately 280. ISM did not interact with the platelet alpha-adrenergic receptor, but increased cAMP in intact platelets. The results are consistent with the concept that ISM inhibition of platelet aggregation and release is mediated by an increase in platelet cAMP. The exact mechanism whereby ISM increases platelet cAMP appears to be that of inhibition of cyclic AMP phosphodiesterase. The effect of ISM on platelet function is one mechanism which might explain the therapeutic effect of ISM in experimental and clinical coronary artery disease.