Peroxynitrite decreases hemostasis in human plasma in vitro.

Coagulopathy has been associated with clinical scenarios that involve reactive nitrogen species such as peroxynitrite (OONO-). Further, OONO- decreases tissue factor and fibrinogen function in vitro. Thus, we hypothesized that exposure of plasma to the OONO- generated with 3-morpholinosydnonimine (SIN-1), a molecule that produces both nitric oxide and superoxide, would result in a decrease in hemostatic function via diminished coagulation protein activity. Hemostatic function of plasma exposed to SIN-1 (0, 1, 5, and 10 mM for 60 min at 37 degrees C) was assessed with thrombelastography, activated partial thromboplastin time, and prothrombin time in the presence or absence of superoxide dismutase (SOD) or an OONO- scavenger. SIN-1 exposure resulted in a significant (P < 0.05), dose-dependent decrease in plasma hemostatic function and concurrent significant (P < 0.05) decreases in activities of factor VII, factor VIII complex, and factor X. Fibrinogen concentration was not affected by SIN-1. Antithrombin and protein C activity also decreased significantly (P < 0.05). Coincubation with SOD or an OONO- scavenger significantly (P < 0.05) attenuated SIN-1 mediated changes in hemostasis and procoagulant/ anticoagulant activity. We conclude that OONO- may decrease hemostatic function in human plasma by nitration of key procoagulants and that OONO- may play a significant role in hemorrhagic states.