MEDROXYPROGESTERONE ACETATE (MPA) INCREASES PAI-1 SECRETION FROM HUVEC AND ELEVATES THE PLASMA-LEVELS OF PAI-I IN-VIVO

Plasma levels of tissue type plasminogen activator (t-PA) and plasmino gen activator inhibitor-1 (PAI-1) in patients administered with medrox yprogesterone acetate (MPA) (800 mg/day) or tamoxifen (20 mg/day) were assayed. Active free PAI-1 levels of patients given MPA were signific antly higher than those either given tamoxifen or post adjuvant therap y, t-PA antigen levels were not different among the three groups. In i n vitro study, treatment of cultured human umbilical vein endothelial cells (HUVEC) with MPA (10(-6)-10(-8) M) decreased PAI-1 levels signif icantly with a trend to decrease in t-PA levels.