Poster 253 - The in vitro and in vivo pharmacological activity of Boiga Dendrophila venom

Poster 253. Congresso da Sociedade Brasileira de Toxinologia, 8., Symposium of the Pan American Section of the International Society on Toxinology, 8., 2004, Angra dos Reis, Brasil. Abstracts... J. Venom. Anim. Toxins incl.Trop. Dis., 2004, 10, 3, p.612.

The In Vitro and In VivoPharmacological Activity of Boiga Dendrophila Venom

1 Monash Venom Group, Department of Pharmacology, Monash University, Vic 3800, Australia; 2 Australian Venom Research Unit, Department of Pharmacology, University of Melbourne, Vic 3010, Australia; 3 Department of Pharmaceutical Biology and Pharmacology, Victorian College of Pharmacy Monash University, Vic 3052, Australia; 4 Department of Biological Sciences, Faculty of Science, National University of Singapore, 119260, Singapore.

The great taxonomical and prey base diversity of Colubrids (non front-fanged snakes) suggests that their venoms may represent a ‘literal gold mine’ for scientists eager to find novel pharmacological probes (Mackessy, 2002). This study further characterises the activity of venom from the colubrine snake, Boiga dendrophila (Mangrove catsnake). In the prostatic segment of the rat vas deferens, cumulative additions of venom (1-150 mg/ml) induced concentration-dependent inhibition of electrically-evoked (0.2 Hz, 0.3 ms, 70-100 V) twitches. The inhibitory effect of venom (100 mg/ml) was attenuated by 8- phenyltheophylline (8-PT) (20 mM) and 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX) (20 mM) but not idazoxan (1 mM), or a combination of ranitidine (0.2 mM) and thioperamide (10 mM). The inhibitory effect of venom (100 mg/ml) was augmented by dipyridamole (10 mM) but abolished by pretreatment with adenosine deaminase (7.5 units/100 ml) suggesting that it contains components with adenosine a1 receptor activity, most likely adenosine. In isolated segments of guinea pig ileum, venom (10-100 µg/ml) caused concentration-dependent contractions which were inhibited by the muscarinic receptor antagonist atropine (0.1 mM) but not by the histamine receptor antagonist mepyramine (0.5 mM). In the anaesthetised rat, venom (5-7.5 mg/g i.v) caused a hypotensive effect. Our data suggests that the venom contains components with purinergic and muscarinic receptor activity.