CYCLIC VARIATION OF PLASMINOGEN ACTIVATION IN HUMAN UTERINE FLUID AND THE INFLUENCE OF AN INTRAUTERINE DEVICE

Activation of plasminogen to plasmin in uterine fluid results in the formation of plasmin‐α2‐antiplasmm complexes. The degree of plasminogen activation was studied during the menstrual cycle in IUD‐users and non‐users. The absence of free plasminogen in the presence of plasmin complexes indicated complete activation of the zymogen. The simultaneous occurrence of free plasminogen and plasmin complexes was interpreted to represent incomplete activation. Results were correlated with the concentration of α2‐antiplasmin, a major inhibitor of urokinase and plasmin. In the midcycle phase of IUD‐non‐users, plasminogen activation was complete and the concentration of α2‐antiplasmin was low. In the luteal phase of the same population the concentration of α2‐arttiplasmin was high and there was no plasminogen activation. In contrast, IUD‐users generally had an incomplete activation of plasminogen throughout the menstrual cycle. Also, their concentrations of α2‐antiplasmin were increased in the proliferative and midcycle phases.