title: Hypotensive and vascular relaxant effects of phospholipase A2 toxins from Papuan taipan (Oxyuranus scutellatus) venom.
abstract: Phospholipase A2 (PLA2) toxins are common and abundant components of Australasian elapid venoms. These toxins are associated with a range of activities including neurotoxicity, myotoxicity and coagulation disturbances. We have recently reported that sudden cardiovascular collapse induced by Papuan taipan (Oxyuranus scutellatus) venom involves a combination of the release of dilator autacoids and a direct effect on the smooth muscle. In this study, we aimed to isolate PLA2 components from Papuan taipan venom and investigate their contribution to the hypotensive action of this venom. O. scutellatus venom was fractionated using size-exclusion high performance liquid chromatography (HPLC), and fractions screened for activity in anaesthetized rats. Fraction three from O. scutellatus venom (i.e. OSC3, 14.2±1.0% of whole venom) produced a 64% decrease in mean arterial pressure. Reverse-phase HPLC indicated that OSC3 consisted of two major components (i.e. OSC3a and OSC3b). OSC3a and OSC3b produced a significant hypotensive response in anaesthetized rats which were attenuated by prior administration of indomethacin or the combination of mepyramine and heparin. N-terminal analysis indicated that OSC3a and b displayed sequence homology to PLA2 toxins isolated from coastal taipan (O. scutellatus scutellatus) venom. These findings indicate that PLA2 components may play an important role in the development of hypotension and vascular relaxation which may contribute to the effects observed after envenoming by these Australasian elapids.
authors.affiliation: Monash Venom Group, Department of Pharmacology, Monash University, Victoria 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, Victoria 3800, Australia; School of Medicine and Public Health, University of Newcastle, New South Wales 2300, Australia.
authors.forename: Geoffrey K
authors.initials: GK
authors.lastname: Isbister
authors.affiliation: Department of Physiology, Monash University, Victoria 3800, Australia.
authors.forename: Marianne
authors.initials: M
authors.lastname: Tare
authors.affiliation: Department of Physiology, Monash University, Victoria 3800, Australia.
authors.forename: Helena C
authors.initials: HC
authors.lastname: Parkington
authors.affiliation: Monash Venom Group, Department of Pharmacology, Monash University, Victoria 3800, Australia. Electronic address: wayne.hodgson@monash.edu.
authors.forename: Wayne C
authors.initials: WC
authors.lastname: Hodgson
mesh_terms: D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004546:Elapid Venoms / Q000737:chemistry / Q000494:pharmacology*; D007022:Hypotension / Q000139:chemically induced*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D054467:Phospholipases A2 / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014665:Vasodilator Agents / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D004546:Elapid Venoms; D014665:Vasodilator Agents; D054467:Phospholipases A2
keywords: Anaesthetized rat; Hypotension; Mesenteric artery; Vascular relaxation; Venom