Effect of Physiological Concentrations of Vasopressin on Components of the Fibrinolytic System

Abstract

SummaryHigh physiological concentrations of plasma vasopressin (aVP) when achieved by infusion cause an increase in plasma factor VIII coagulant activity and shortening of the euglobulin clot lysis time (ECLT). To investigate the effects of aVP on components of the fibrinolytic pathway and on thrombin generation, t healthy volunteers were infused with saline for 30 min followed by aVP for L hour and blood samples taken every 30 min for measurement of aVR ECtf tissue-type plasminogen activator (t-PA), t-PA inhibition (tPA-I), plasminogen activator inhibitor L (PAI-1 Ag), activated partial thromboplastin time (APTT), fibrinopeptide A (FPA), fibrinopeptide B 15-42 (FPBß 15-42) and crosslinked fibrin breakdown products (XL-FDP). Plasma aVP rose to a median of 75 pg/ml after 90 min and fell to 13.8 pdml 30 min later. The APTT fell from 43.5 to 35 sec (p <0.01) but there was no change in plasma FPA or in XL-FDP. Plasminogen activator activity (106/ECLT2) increased from 25 to 736 units (p <0.01) and t-PA from 200 to 1012 mlU/ml (p <0.01). tPA-I fell from 8.0 to 2.7 IU/ml at 90 min (p <0.05) but PAI-1 Ag remained unchanged. Plasma FPBß 15-42 was 2.4 and 1.2 pmol/ml before infusion with aVP and showed a small rise to 3.5 pmol/ml after 60 min (p <0.05). The results show the effects of aVP on fibrinolysis are mediated by an increase in t-PA. In the absence of thrombin generation the rise in t-PA was not accompanied by changes in XL-FDP.