title: Prothrombin activator-like toxin appears to mediate cardiovascular collapse following envenoming by Pseudonaja textilis.
abstract: Brown snake (Pseudonaja spp.)-induced early cardiovascular collapse is a life-threatening medical emergency in Australia. We have previously shown that this effect can be mimicked in animals and is mediated via the release of endogenous mediators. In the present study, we aimed to purify and characterize the component in Pseudonaja textilis venom which induces cardiovascular collapse following envenoming. The component (fraction 3) was isolated using a combination of techniques including hydroxyapatite and reverse phase chromatography. Fraction 3 (10 or 20 μg/kg, i.v.) produced a rapid decrease in mean arterial pressure (MAP) followed by cardiovascular collapse. Fraction 3-induced early collapse was abolished by prior administration of smaller priming doses of fraction 3 (i.e. 2 and 5 μg/kg, i.v.) or heparin (300 units/kg, i.v.). P. textilis whole venom (1 and 3 μg/ml), but not fraction 3 (1 or 3 μg/ml), induced endothelium-dependent relaxation in isolated rat mesenteric arteries. SDS-PAGE gel indicated the presence of 9-10 protein bands of fraction 3. Using proteomic based analysis some protein bands of fraction 3 were identified as subunits of venom prothrombin activator, pseutarin C of P. textilis venom. Our results conclude that prothrombin activator-like toxin is likely to be a contributor to the rapid collapse induced by P. textilis venom.
authors.affiliation: Monash Venom Group, Department of Pharmacology, Monash University, VIC, 3800, Australia; Department of Pharmacology, Phramongkutklao College of Medicine, Bangkok, 10400, Thailand.
authors.forename: Janeyuth
authors.initials: J
authors.lastname: Chaisakul
authors.affiliation: Monash Venom Group, Department of Pharmacology, Monash University, VIC, 3800, Australia; Department of Clinical Pharmacology and Toxicology, Calvary Mater, NSW, 2298, Australia.
authors.forename: Geoffrey K
authors.initials: GK
authors.lastname: Isbister
authors.affiliation: Department of Clinical Pharmacology and Toxicology, Calvary Mater, NSW, 2298, Australia.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: O'Leary
authors.affiliation: Department of Physiology, Monash University, VIC, 3800, Australia.
authors.forename: Helena C
authors.initials: HC
authors.lastname: Parkington
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, VIC, 3800, Australia.
authors.forename: A Ian
authors.initials: AI
authors.lastname: Smith
authors.affiliation: Monash Venom Group, Department of Pharmacology, Monash University, VIC, 3800, Australia.
authors.forename: Wayne C
authors.initials: WC
authors.lastname: Hodgson
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, VIC, 3800, Australia. Electronic address: Sanjaya.Kuruppu@monash.edu.
authors.forename: Sanjaya
authors.initials: S
authors.lastname: Kuruppu
mesh_terms: D000818:Animals; D001315:Australia; D002319:Cardiovascular System / Q000187:drug effects*; D004546:Elapid Venoms / Q000737:chemistry* / Q000633:toxicity*; D017815:Elapidae; D008297:Male; D011516:Prothrombin / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012909:Snake Bites
chemical_list: D004546:Elapid Venoms; D011516:Prothrombin
keywords: Anaesthetized rat; Brown snake; Collapse; Prothrombin activator; Snake venom