NO INFLUENCE OF PROINSULIN AND INSULIN ON PLASMA-LEVELS OF PLASMINOGEN-ACTIVATOR INHIBITOR TYPE-1 AND TISSUE-PLASMINOGEN ACTIVATOR IN YOUNG-WOMEN BEFORE AND DURING INTAKE OF CONTRACEPTIVE STEROIDS

Clinical observations in patients predisposed to cardiovascular disord ers and recent experimental observations suggest that proinsulin and i nsulin participate in the regulation of fibrinolysis in vivo. In the p resent study, we examined if proinsulin and insulin affect the constit utive (fasting) secretion of plasminogen activator inhibitor type 1 (P AI-1) and tissue plasminogen activator (t-PA) in young healthy women ( N = 17). We also measured the antigen concentrations of PAI-1 and t-PA during slow and fast changes in proinsulin and insulin levels induced by oral (OGTT) and intravenous (IVGTT) glucose tolerance tests. The a ssessments were performed before and after 6 months of treatment with contraceptive steroids, which have a well-defined influence on the fib rinolytic variables. We observed no consistent correlations between fa sting values of proinsulin, insulin, PAI-1, and t-PA either before or during hormonal treatment. Before hormonal treatment, PAI-1 and t-PA a ntigen levels decreased (P < .05) during the hyperproinsulinemia and h yperinsulinemia induced by the OGTT and IVGTT. After hormonal intake f or 6 months, a decrease only in t-PA concentrations during the OGTT wa s observed despite similar proinsulin and insulin responses to the glu cose loads. Our findings suggest that proinsulin and insulin have no i nfluence on the regulation of plasma levels of PAI-1 and t-PA in young healthy women, irrespective of intake of contraceptive steroids. Copy right (C) 1996 by W.B. Saunders Company