title: Southern copperhead venom enhances tissue-type plasminogen activator induced fibrinolysis but does not directly lyse human plasma thrombi.
abstract: In addition to degrading fibrinogen as a source of consumptive coagulopathy, purified fractions of southern copperhead (Agkistrodon contortrix contortrix; A. c. contortrix) venom has been demonstrated to enhance fibrinolysis. The goal of this investigation was to characterize the kinetic fibrinolytic profile of A. c. contortrix venom in the absence and presence of tissue-type plasminogen activator (tPA) to determine if intact venom had tPA independent fibrinolytic properties. Utilizing thrombelastographic methods, the coagulation and fibrinolytic kinetic profiles of human plasma exposed to A. c. contortrix venom (0-6 μg/ml) were determined in the absence or presence of tPA (0-100 IU/ml). Then, plasma was exposed to 0-6 μg/ml of venom without tPA added and coagulation observed for 3 h. Venom significantly prolonged the onset of coagulation, decreased the velocity of thrombus growth but did not significantly decrease clot strength. In the presence of tPA, venom significantly decreased clot strength, shortened the time of onset of fibrinolysis, decreased clot lysis time but did not significantly affect the maximum rate of lysis. Lastly, while venom exposure in the absence of tPA significantly prolonged the onset of coagulation and decreased the velocity of clot growth, venom exposure did not result in detectable fibrinolysis over the 3 h observation period. A. c. contortrix venom enhances tPA mediated fibrinolysis by degrading plasma coagulation kinetics. Intact A. c. contortrix venom does not possess sufficient fibrinolytic activity to cause fibrinolysis in human plasma at the concentration tested.
authors.affiliation: Department of Anesthesiology, The University of Arizona College of Medicine, 1501 North Campbell Avenue, P.O. Box 245114, Tucson, AZ, 85724-5114, USA. vgnielsen333@gmail.com.
authors.forename: Vance G
authors.initials: VG
authors.lastname: Nielsen
mesh_terms: D001777:Blood Coagulation / Q000187:drug effects; D003435:Crotalid Venoms / Q000494:pharmacology*; D004357:Drug Synergism; D005342:Fibrinolysis / Q000187:drug effects*; D005343:Fibrinolytic Agents / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D010949:Plasma / Q000187:drug effects / Q000502:physiology; D013916:Thrombelastography; D013927:Thrombosis / Q000188:drug therapy; D010959:Tissue Plasminogen Activator / Q000494:pharmacology*
chemical_list: C031442:Agkistrodon venoms; D003435:Crotalid Venoms; D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator
keywords: Fibrinogenolysis; Fibrinolysis; Snake venom; Thrombelastography; Tissue-type plasminogen activator