RESUMO
The anticoagulant activity of antithrombin III (ATIII), as observed in a plasma-free system consisting of thrombin and fibrinogen, is readily reduced by acetaldehyde (AcH) at concentrations of 447, 89.4, and 17.9 mM. Whereas control thrombin-fibrinogen mixtures clotted in 17.7+/-0.75 sec, ATIII prolonged clotting time to 55.0+/-1.75 sec on preincubation with thrombin for 30 min at room temperature. On subsequent preincubation of ATIII with the AcH for 30 min at room temperature and passage of the mixture through Sephadex G-25 minicolumns to remove excess AcH, the eluates were tested for anticoagulant activity. Clotting times of 20.9+/-1.0, 32.3+/-1.0, and 45.3+/-1.6 sec were obtained with 447, 89.4, and 17.9 mM AcH-ATIII mixtures, respectively. These data suggest that functional groups on ATIII, such as guanidiniums, aminos, and others are susceptible to adduct formation with AcH, thereby altering the shape and charge of the anticoagulant. As a consequence of this type of reaction, an altered molecule of reduced biological activity may be produced. These experimental results may explain, in part, the reduction in ATIII levels reported by others in patients with alcoholic liver disease.
