Abstract
The effects of protopine on blood platelet aggregation were investigated in in vivo, ex vivo, and in vitro models. Protopine (0.25 mM/kg,p.o.) showed stronger inhibitory effects on endotoxin-induced disseminated intravascular coagulation (DIC) in rats and on pulmonary thromboembolism in mice compared with that of acetylsalicylic acid and dipyridamole (1.0 mM/kg, p.o., respectively), and also inhibited collagen- and ADP-induced rat ex vivo blood platelet aggregation. Protopine was found to intensify the inhibitory effect of PGI2 on platelet aggregation, but there was no effect on PGI2 generation from rat arterial tissue. Oral administration of acetylsalicylic acid (0.1 mM/kg) strongly inhibited the PGI2 generation. These results suggest that protopine will be able to serve as an anti-thrombic agent without inhibitory effects of PGI2 generation as observed with acetylsalicylic acid.
