Summary
Basal t-PA antigen concentration, PAI-I activity and tibrinolytic capacity was studied
in plasma from 20 healthy teenager girls (age 15.9 ± 1.3 years) and two groups of
older healthy volunteers, consisting of L7 women (age 32 ± 8 years, group 1) and 35
men (age 34 ± 8 years, group 2). Basal t-PA antigen concentrations in plasma were
found to be highly age-dependent with higher values with increasing age. The teenager
girls had significantly lower values compared with the two groups of elderly volunteers.
PAI-I levels were significantly higher in plasma from the teenager girls and the fibrinolytic
capacity after 15 min of venous occlusion was significantly lower.
In this study we also determined the effect of low-dose oral contraceptives (OC) on
coagulation and fibrinolysis in the teenager group. Each teenager served as her own
control with samples drawn before and on OC after 4 months of use. The coagulation
parameters, factor VIII activity, AT III, protein C and platelet counts were all within
reference values before and on OC. The fibrinolytic activity in plasma after venous
occlusion (15 min) increased significantly when the teenagers had used OC for 4 months.
This phenomenon was explained by significantly decreased PAI levels and also by significantly
increased t-PA antigen release from the vessel wall after venous occlusion.
Keywords
Fibrinolysis - Tissue-type plasminogen activator - Tissue-type plasminogen activator
inhibitor - Oral contraceptives