title: Isolation and pharmacological characterization of a phospholipase A2 myotoxin from the venom of the Irian Jayan death adder (Acanthophis rugosus).
abstract: 1. It has long been thought that death adder venoms are devoid of myotoxic activity based on studies done on Acanthophis antarcticus (Common death adder) venom. However, a recent clinical study reported rhabdomyolysis in patients following death adder envenomations, in Papua New Guinea, by a species thought to be different to A. antarcticus. Consequently, the present study examined A. rugosus (Irian Jayan death adder) venom for myotoxicity, and isolated the first myotoxin (acanmyotoxin-1) from a death adder venom. 2. A. rugosus (10-50 micro g ml(-1)) and acanmyotoxin-1 (MW 13811; 0.1-1 micro M) were screened for myotoxicity using the chick directly (0.1 Hz, 2 ms, supramaximal V) stimulated biventer cervicis nerve-muscle (CBCNM) preparation. A significant contracture of skeletal muscle and/or inhibition of direct twitches were considered signs of myotoxicity. This was confirmed by histological examination. 3. High phospholipase A(2) (PLA(2)) activity was detected in both A. rugosus venom (140.2+/-10.4 micro mol min(-1) mg(-1); n=6) and acanmyotoxin-1 (153.4+/-11 micro mol min(-1) mg(-1); n=6). Both A. rugosus venom (10-50 micro g ml(-1)) and acanmyotoxin-1 (0.1-1 micro M) caused dose-dependent inhibition of direct twitches and increase in baseline tension (n=4-6). In addition, dose-dependent morphological changes in skeletal muscle were observed. 4. Prior incubation (10 min) of CSL death adder antivenom (5 units ml(-1); n=4) or inactivation of PLA(2) activity with 4-bromophenacyl bromide (1.8 mM; n=4) prevented the myotoxicity caused by acanmyotoxin-1 (1 micro M). 5. Acanmyotoxin-1 (0.1 micro M; n=4) displayed no significant neurotoxicity when it was examined using the indirectly (0.1 Hz, 0.2 ms, supramaximal V) stimulated CBCNM preparation. 6. In conclusion, clinicians may need to be mindful of possible myotoxicity following death adder envenomation in Irian Jaya.
authors.affiliation: Monash Venom Group, Department of Pharmacology, P.O. Box 13E, Monash University, Victoria 3800, Australia.
authors.forename: Janith C
authors.initials: JC
authors.lastname: Wickramaratna
authors.forename: Bryan G
authors.initials: BG
authors.lastname: Fry
authors.forename: Marie-Isabel
authors.initials: MI
authors.lastname: Aguilar
authors.forename: R Manjunatha
authors.initials: RM
authors.lastname: Kini
authors.forename: Wayne C
authors.initials: WC
authors.lastname: Hodgson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D004546:Elapid Venoms / Q000201:enzymology / Q000302:isolation & purification* / Q000494:pharmacology*; D017815:Elapidae; D066298:In Vitro Techniques; D007214:Indonesia; D008297:Male; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000294:innervation / Q000473:pathology; D010741:Phospholipases A / Q000302:isolation & purification* / Q000494:pharmacology*; D054467:Phospholipases A2
chemical_list: D004546:Elapid Venoms; C112921:acanthin; D010741:Phospholipases A; D054467:Phospholipases A2