Changes in blood viscosity with the recombinant tissue plasminogen activator alteplase

We measured whole blood viscosity to investigate the time course of the fibrinolytic activity of the recombinant tissue plasminogen activator alteplase. Changes in blood viscosity over time were determined using an oscillation-type viscometer at a shear rate of 400 to 500 per second. Blood viscosity initially increased with alteplase as in untreated blood, but then decreased, reflecting the fibrinolytic activity of generated plasmin. Blood viscosity subsequently stabilized at a level below the initial value owing to the dissolution of both fibrin and fibrinogen by alteplase. To our knowledge, the present study is the first to examine the time course of changes in BV during fibrin formation and degradation. The results indicated that the fibrinolyic agent alteplase might provide the additional benefit of increasing blood flow by lowering blood viscosity.