Dipyridamole: a potent stimulator of prostacyclin (PGI2) biosynthesis

1 Dipyridamole (0.01 to 0.75 mM) increased prostacyclin (PGI2) biosynthesis from tritiated arachidonic acid in rat stomach fundus homogenates by 21 to 350%. The transformation of prostaglandin H2 (PGH2) to PGI2 by a microsomal fraction of pig aorta was stimulated by dipyridamole at 0.1 M by 63%. 2 In the isolated perfused heart of the rabbit dipyridamole at 1 and 5 micrograms/ml increased PGI2 release by 70% and 146% respectively. 3 Our results show a stimulation of the second step in PGI2 biosynthesis (from endoperoxides) by dipyridamole. This effect should be considered in relation to the therapeutic usage of the drug in myocardial infarction.