IngentaConnect The in vitro and in vivo pharmacological activity of Boiga dendro...

Abstract:

Summary

1 The great taxonomic 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).

2 While pharmacological characterization is lacking for most of these venoms, this is even more so with regard to activity of colubrid venoms on the mammalian autonomic nervous system. This study characterizes the activity of venom from the colubrid, Boiga dendrophila using in vitro smooth muscle preparations and the anaesthetized rat.

3 In the prostatic segment of the rat vas deferens, cumulative additions of venom (1-150 μg ml⁻¹) induced concentration-dependent inhibition of electrically evoked (0.2 Hz, 0.3 ms, 70-100 V) twitches. The inhibitory effect of venom (100 μg ml⁻¹) was attenuated by 8-phenyltheophylline (8-PT) (20 μm) and 8-cyclopentyl-1, 3-dipropylxanthine (20 μm) but not idazoxan (1 μm), or a combination of ranitidine (0.2 μm) and thioperamide (10 μm). The inhibitory effect of venom (100 μg ml⁻¹) was augmented by dipyridamole (10 μm) but abolished by pretreatment with adenosine deaminase (7.5 units/100 μl) suggesting that it contains components with adenosine A₁ receptor activity, most likely adenosine.

4 In isolated segments of guinea-pig ileum, venom (10-100 μg ml⁻¹) caused concentration-dependent contractions which were inhibited by the muscarinic receptor antagonist atropine (0.1 μm) but not by the histamine receptor antagonist mepyramine (0.5 μm).

5 In the anaesthetized rat, venom (5-7.5 mg kg⁻¹, i.v.) caused a hypotensive effect.

6 Our data suggest that the venom contains components with purinergic and muscarinic receptor activity.

Keywords: anaesthetized rat; colubrid; guinea-pig ileum; rat vas deferens; snake; venom

Document Type: Research article

DOI: 10.1111/j.1474-8673.2004.00322.x

Affiliations: 1: Monash Venom Group, Department of Pharmacology, Monash University, Clayton, Vic. 3800 2: Australian Venom Research Unit, Department of Pharmacology, University of Melbourne, Melbourne, Vic. 3010 3: Department of Pharmaceutical Biology and Pharmacology, Victorian College of Pharmacy, Monash University, Parkville, Vic. 3052, Australia 4: Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543

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The in vitro and in vivo pharmacological activity of Boiga dendrophila (mangrove catsnake) venom