Evaluation of the contribution of platelets to clot strength by thromboelastography in rabbits: The role of tissue factor and cytochalasin D

The contribution of platelets and soluble clotting components to clot stren gth has been the focus of several clinical studies using thromboelastograph y; it would, therefore, be beneficial to develop an animal model with which to mechanistically approach hemostatic disorders. Thus, we proposed to det ermine if the contribution of platelet function (G(P), dyne/cm(2)) and solu ble components of the coagulation pathway to total clot strength (G(T)) in rabbits were similar to those in humans. Blood was sampled from the ear art eries of conscious rabbits (n = 12); 350 mu L of the blood was placed in a thromboelastograph. Ten microliters of normal saline, cytochalasin D (an in hibitor of microtubule function, 10 mu M final concentration), or tissue fa ctor (a potent stimulator of platelet function, 0.00625% final concentratio n) was added to the blood sample, and thromboelastography performed for 1 h . The G(T) (mean +/- SD) was significantly (P < 0.001) different among samp les exposed to normal saline, cytochalasin D, or tissue factor, with G(T) v alues of 7238 +/- 1432, 937 +/- 372, and 16,556 +/- 3314, respectively. G(P ) was responsible for 87% and 94% of G(T) in the absence or presence of tis sue factor, respectively. G(T) did not significantly correlate with platele t concentration in the absence or presence of tissue factor. The contributi on of G(P) to G(T) is similar to that observed in humans.