Astedt B, Lindoff C, Lecander I
Department of Obstetrics and Gynecology, University Hospital, Lund, Sweden.
Semin Thromb Hemost. 1998;24(5):431-5. doi: 10.1055/s-2007-996035.
Marked changes in the hemostasis system, especially increases in PAI-2, are observed during pregnancy and at delivery. This inhibitor is produced by placental trophoblasts and by macrophages. PAI-2 occurs in two forms, a LMW and a HMW form. LMW PAI-2 is intracellular, HMW PAI-2 is secreted. PAI-2 inhibits both u-PA and two-chain t-PA. PAI-2 seems to be involved in the processes of invasion and remodeling of fetal and uterine tissues. It may protect against premature placental separation and secure hemostasis at parturition. Excess levels of PAI-2 in amniotic fluid may protect membranes from premature rupture. An imbalance between fibrinolytic activators and inhibitors may also be related to intracranial hemorrhage in premature infants. During preeclampsia t-PA and PAI-1 levels are markedly increased in plasma, and in cases of intrauterine growth retardation, u-PA and PAI-2 levels are decreased. While elevated PAI-1 concentrations might be helpful markers of severity of preeclampsia, decreased PAI-2 levels seem to indicate decreased placental function and intrauterine growth retardation.
在孕期及分娩时，止血系统会出现显著变化，尤其是纤溶酶原激活物抑制剂-2（PAI-2）水平升高。这种抑制剂由胎盘滋养层细胞和巨噬细胞产生。PAI-2有两种形式，即低分子量（LMW）形式和高分子量（HMW）形式。LMW PAI-2存在于细胞内，HMW PAI-2则被分泌出来。PAI-2可抑制尿激酶型纤溶酶原激活物（u-PA）和双链组织型纤溶酶原激活物（t-PA）。PAI-2似乎参与了胎儿和子宫组织的侵袭与重塑过程。它可能预防胎盘过早剥离，并确保分娩时的止血。羊水中PAI-2水平过高可能保护胎膜免于过早破裂。纤溶激活剂与抑制剂之间的失衡也可能与早产儿颅内出血有关。子痫前期时，血浆中t-PA和PAI-1水平显著升高，而在胎儿宫内生长受限的情况下，u-PA和PAI-2水平降低。虽然PAI-1浓度升高可能是子痫前期严重程度的有用标志物，但PAI-2水平降低似乎表明胎盘功能下降和胎儿宫内生长受限。
