[Effects of neferine on platelet aggregation in rabbits]

Neferine (Nef), a hypotensive agent with antiarrythmic action, is a dibenzyl isoquinoline alkaloid isolated from a Chinese medicinal herb (Nelumbo nucifera Gaertn). Its effects on platelet aggregation and TXA2/PGI2 and cAMP/cGMP balance were studied with methods of turbidimetry and RIA. Nef was shown to significantly inhibit rabbit platelet aggregation induced by ADP, collagen, arachidonic acid (AA) and platelet-activating factor (PAF) with IC50 of 16, 22, 193 and 103 mumol.L-1, respectively. Nef was found to increase vascular 6-keto-PGF1 alpha and platelet cAMP levels in dose-dependent manner, but inhibit AA stimulated TXA2 release from platelets. Nef showed no significant effect on the platelet cGMP level. The results suggest that the mechanism of Nef on platelet aggregation is related to regulation of TXA2/PGI2 and cAMP/cGMP balance.