Measurement of activities of urinary (u-PA) and tissue plasminogen activator (t-PA)
and analysis of euglobulin lysis times (ELTs) and prekallikrein were performed simultaneously
using the plasma of normal pregnant women and nonpregnant women. The activities of
plasminogen activators were determined by the method of electrophoretic zymography.
The activity of low-molecular-weight (LMW) u-PA was significantly decreased at the
onset of labor (p = 0.05) compared with that during the latter half of pregnancy.
The same tendency was observed in the analysis of prekallikrein. On the contrary,
no significance was shown in activities of high-molecular-weight (HMW) u-PA or t-PA.
It is suggested that the action of kallikrein on low-molecular-weight u-PA causes
it to change into plasmin at the onset of labor.
Tissue-type plasminogen activator (t-PA) - urinary plasminogen activator (u-PA) -
zymography - hemostasis - onset of labor
