In vitro neuromuscular activity of 'colubrid' venoms: clinical and evolutionary implications.
In this study, venoms from species in the Colubrinae, Homalopsinae, Natricinae, Pseudoxyrhophiinae and Psammophiinae snake families were assayed for activity in the chick biventer cervicis skeletal nerve muscle preparation. Boiga dendrophila, Boiga cynodon, Boiga dendrophila gemincincta, Boiga drapiezii, Boiga irregularis, Boiga nigriceps and Telescopus dhara venoms (10 microg/ml) displayed postsynaptic neuromuscular activity as evidenced by inhibition of indirect (0.1 Hz, 0.2 ms, supramaximal V) twitches. Neostigmine (5 microM) reversed the inhibition caused by B. cynodon venom (10 microg/ml) while the inhibitory effects of Psammophis mossambicus venom (10 microg/ml) spontaneously reversed, indicating a reversible mode of action for both venoms. Trimorphodon biscutatus (10 microg/ml) displayed irreversible presynaptic neurotoxic activity. Detectable levels of phospholipase A2 activity were found only in T. biscutatus, T. dhara and P. mossambicus venoms. The results demonstrate a hitherto unsuspected diversity of pharmacological actions in all lineages which may have implications ranging from clinical management of envenomings to venom evolution.
Monash Venom Group, Department of Pharmacology, Monash University, Melbourne, Vic. 3800, Australia.
Natalie G
NG
Lumsden
Bryan G
BG
Fry
R
R
Manjunatha Kini
Wayne C
WC
Hodgson
D000704:Analysis of Variance; D000818:Animals; D002645:Chickens; D009119:Muscle Contraction / Q000187:drug effects*; D009388:Neostigmine / Q000494:pharmacology; D009465:Neuromuscular Agents / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000633:toxicity*; D009469:Neuromuscular Junction / Q000187:drug effects*; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010802:Phylogeny; D012910:Snake Venoms / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000633:toxicity*; D012911:Snakes; D013045:Species Specificity; D013997:Time Factors
D009465:Neuromuscular Agents; D012910:Snake Venoms; D009388:Neostigmine; D010741:Phospholipases A; D054467:Phospholipases A2