Carbon monoxide-releasing molecule-2 enhances coagulation in rabbit plasma and decreases bleeding time in clopidogrel/aspirin-treated rabbits

Administration of carbon monoxide derived from carbon monoxide-releasing molecules has been demonstrated to enhance coagulation in vitro at small concentrations (100-200 μmol/l) in human and rabbit plasma. We sought to determine if carbon monoxide-releasing molecule-2 [tricarbonyldichlororuthenium (II) dimer, CORM-2] would improve coagulation in rabbit plasma in vitro via thrombelastography and in an in vivo preclinical rabbit model of ear bleeding time following administration of clopidogrel (20 mg/kg) with aspirin (10 mg/kg) via gavage. Addition of 100 μmol/l CORM-2 to rabbit plasma significantly improved coagulation. This procoagulant effect was blocked by pre-exposure of plasma to an agent that converts hemefibrinogen to methemefibrinogen in human plasma, preventing carbon monoxide binding and enhancement of coagulation. Rabbit ear bleeding time was 5.8 ± 1.1 min 2-3 h after clopidogrel/aspirin administration. Bleeding time significantly decreased to 2.6 ± 0.6 min, 5 min after administration of CORM-2 (10 mg/kg; 279 μmol/l 'best-case' instantaneous concentration) intravenously. CORM-2 enhances plasmatic coagulation in a manner similar to that of human plasma in vitro, and plasmatic coagulation is enhanced in vivo by CORM-2 as well. Additional preclinical investigation of the effects of CORM-2 on coagulopathy (e.g. heparin or hemodilution mediated) utilizing this rabbit model is planned.