Cultured granulosa cells produce two plasminogen activators and an antiactivator, each regulated differently by gonadotropins.

Although treatment of cultured granulosa cells with gonadotropins increases their fibrinolytic activity, the biochemical nature of this effect is unclear. We have used sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fibrin autography techniques to characterize the fibrinolytic components secreted by granulosa cells. The fibrinolytic activity of these cells results from the production of both a tissue-type plasminogen activator (t-PA) and a urokinase-like activator (u-PA). The cells also produce an inhibitor of fibrinolysis (antiactivator). FSH and LH stimulate t-PA activity and suppress antiactivator activity, while u-PA activity is not affected by the gonadotropins. The differential regulation of these molecules by the gonadotropins may be essential for ovulation.