TISSUE-TYPE PLASMINOGEN-ACTIVATOR AFTER VENOUS OCCLUSION IN PREGNANCYAND PUERPERIUM

Pregnancy is associated with depressed fibrinolysis as judged from the decreased fibrinolytic response to venous occlusion. In order to eluc idate if this decreased response is due to an increase in plasminogen activator inhibitors 1 and 2 (PAI-1, PAI-2), and/ or to decreased rele ase of tissue-type plasminogen activator (t-PA) antigen during venous occlusion, 36 women (18 women with normal pregnancy and 18 with gestat ional hypertension without proteinuria) were followed during pregnancy and puerperium. In each woman a 20 min venous occlusion was performed in the second and in the third trimester of pregnancy and 3 days afte r delivery. The increase in t-PA antigen after venous occlusion relati ve to basal value was in the second trimester of pregnancy on average 3.7 fold, in the third trimester 4.4 fold, and so not reduced compared to non-pregnant women (3.7 fold increase). After delivery the increas e in t-PA antigen was significantly enhanced (8.5 fold, p < 0.005). Th e fibrinolytic response to venous occlusion measured by euglobulin and t-PA activity was significantly decreased in the third trimester comp ared to nonpregnant values (both p < 0.005) and returned to somewhat h igher (euglobulin clot lysis) or significantly higher (t-PA activity, p < 0.01) values 3 days after delivery. Decreased euglobulin and t-PA activity after venous occlusion in the third trimester coincided with significant increases in basal PAI activity, PAI-1 antigen and PAI-2 a ntigen (2.9, 2.5 and > 30 fold increase relative to non-pregnant value s, respectively, all p < 0.001). No significant differences in fibrino lytic variables were observed between normotensive and hypertensive pr egnant women. It was concluded that t-PA antigen release during venous occlusion is not decreased during pregnancy and puerperium, and that decreased fibrinolytic response measured by global methods should be a ttributed to increased t-PA inhibitors. Gestational hypertension witho ut proteinuria is not characterized by changes in fibrinolytic respons es different from those observed in normal pregnancy.