Effect of colchicine on heparin antithrombotic activity in Def⁺⁺mice. (A-B) Prevention of IVC thrombosis by colchicine. (A) One hour after IVC stenosis was induced, mice were given IV saline (n = 13), heparin (0-200 U/kg) (n = 17), a fixed dose of colchicine (0.5 mg/kg) (n = 16), or heparin + colchicine (n = 21). WT mice (red) and Def⁺⁺ mice (blue) were given heparin alone. WT mice (purple) and Def⁺⁺ mice (green) were given heparin and colchicine. Clots were extracted and weighed 72 hours after stenosis (*, #, &, P < .05). (B) IVC stenosis was induced as in panel A. One hour later, mice were given IV saline (n = 9), colchicine (0-0.5 mg/kg) (n = 17), a fixed dose of heparin (10 U/kg) (n = 14), or heparin + colchicine (n = 14). WT mice (red) and Def⁺⁺ mice (blue) were given colchicine alone. WT mice (purple) and Def⁺⁺ mice (green) were given heparin and colchicine. Clots were extracted and weighed 72 hours after stenosis (*, #, P < .05). (C-D) Effect of colchicine on bleeding. (C) Mice were treated as in panel A. Tail-bleeding times were measured at 72 hours after receiving the indicated doses of heparin, colchicine, or both. WT mice (red) and Def⁺⁺ mice (blue) were given heparin alone. WT mice (purple) and Def⁺⁺ mice (green) were given heparin and colchicine. (D) The hemoglobin concentration in blood extravasated during the initial 30 minutes after transection. WT mice (red) and Def⁺⁺ mice (blue) were given heparin alone. WT mice (purple) and Def⁺⁺ mice (green) were given heparin and colchicine (*, #, P < .05). (E) Clot weight (red) and tail-bleeding times (blue) were measured 72 hours after IVC stenosis, followed 1 hour later by IV administration of colchicine (0.1 mg/kg) (n = 14), heparin (10 U/kg) (n = 14), or both (n = 11), as described in panel A. The mean ± SD are shown (*, #, P < .05).