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Estimation of neurotoxic and myotoxic activities of snake venoms using a simple in vitro assay
1989 Supported by U.S. Army Contract No. DAMD 17-88-C-8024o
References Somani, S.M. and Khalique, A., 1986, Fund. Appl. Toxicol. 6, 327. Somani, S.M. and Khalique, A., 1987, Drug Metabol. Dispos. 15, 627. Somani, S.M., 1989, Biopharma. and Drug Disp. 10, 187-203.
Estimation of neurotoxic and myotoxic activities of snake venoms using a simple/n vitro assay Harvey, A.L. and T h o m s o n , E. Department of Physiology and Pharmacology, University of Strathclyde, George Street, Glasgow G! I XW. U.h:
Snake bite is a serious medical problem in many parts of the world. Specific antivenoms form the basis of most therapy, but there is a need for simple assays that could be used to standardise and compare different preparations of antivenoms. The World Health Organisation have proposed that there should be a panel of representative snake venoms that should be used for experiments on antivenoms (WHO, 1981). Methods have been determined for quantifying the defibrinogenating, procoagulant, haemorrhagic, and necrotizing properties of venoms (Theakston and Reid, 1983). In an attempt to provide a rapid, convenient means of examining the paralysing actions of snake venoms, we have assessed the myotoxic and neurotoxic effects of the standard venoms using a simple in vitro nerve-muscle preparation. The eight international reference snake venoms proposed by the WHO were assessed using the chick biventer cervicis nerve-muscle preparation (Ginsborg and Warriner, 1960). Preparations were stimulated at 0.1 Hz via the motor nerve, and also by exogenous acetylcholine and carbachol (to assess effects on cholinoceptor sensitivity), and by KCI (to assess effects; directly on muscle contractility). Naja m~ja kaouthia (Thailand cobra) and Notechis scutatus (Australian tiger snake) venoms selectively blocked neuromuscular transmission at low concentrations (1-5/z/ml); higher concentrations blocked twitch responses more rapidly, but also resulted in dir ~et effects on muscle fibres, as revealed by slow contractures and a loss in sensitivity to KCl-induced depolarization. Vipera russelli (Russell's viper) venom from Thailand (10-20 pg/ml) also blocked neuromuscular transmission, but only produced small contractures at higher concentrations (100/zg/ml). The other venoms did not have selective effects on neuromuscular transmission. Echis carinatus (carpet viper) venom from Iran and Mali (100-200/tg/ml) and Crotalus atrox (Western diamondback rattlesnake from U.S.A.) venom (10-100 pg/ml) induced eontraetures and blocked responses to cholinergic stimulation and to KCI. Venoms of Bothrops atrox asper (Fer-de-lance from Costa Rica) and Trimeresurus flavoviridis (Okinawa habu from Japan) slowly produced partial block of all forms of stimulation after preparations were exposed to 50-100 ~ag/ml. These effects are consistent ,,~th the cl/nical symptoms after envenomation by these snakes. We conclude that the chick biventer cervicis preparation can be used as a simple in oitro assay to determine the potential neurotoxic and myotoxic effects of snake venoms. It could also be used to test the neutralising potency of antivenom preparations. References Ginsborg, B.L. and Warriner, J., 1960, Br. J. Pharmac. Chemother. 15, 410. Th~ston, R.D.G. ~_ndReid, H.A., 1983, Bull. WHO 61, 949. WHO, 1981, Progress in the Characterization of Venoms and Sta:'_~r~ization of Antivenom~, WHO, Geneva.
References Somani, S.M. and Khalique, A., 1986, Fund. Appl. Toxicol. 6, 327. Somani, S.M. and Khalique, A., 1987, Drug Metabol. Dispos. 15, 627. Somani, S.M., 1989, Biopharma. and Drug Disp. 10, 187-203.
Estimation of neurotoxic and myotoxic activities of snake venoms using a simple/n vitro assay Harvey, A.L. and T h o m s o n , E. Department of Physiology and Pharmacology, University of Strathclyde, George Street, Glasgow G! I XW. U.h:
Snake bite is a serious medical problem in many parts of the world. Specific antivenoms form the basis of most therapy, but there is a need for simple assays that could be used to standardise and compare different preparations of antivenoms. The World Health Organisation have proposed that there should be a panel of representative snake venoms that should be used for experiments on antivenoms (WHO, 1981). Methods have been determined for quantifying the defibrinogenating, procoagulant, haemorrhagic, and necrotizing properties of venoms (Theakston and Reid, 1983). In an attempt to provide a rapid, convenient means of examining the paralysing actions of snake venoms, we have assessed the myotoxic and neurotoxic effects of the standard venoms using a simple in vitro nerve-muscle preparation. The eight international reference snake venoms proposed by the WHO were assessed using the chick biventer cervicis nerve-muscle preparation (Ginsborg and Warriner, 1960). Preparations were stimulated at 0.1 Hz via the motor nerve, and also by exogenous acetylcholine and carbachol (to assess effects on cholinoceptor sensitivity), and by KCI (to assess effects; directly on muscle contractility). Naja m~ja kaouthia (Thailand cobra) and Notechis scutatus (Australian tiger snake) venoms selectively blocked neuromuscular transmission at low concentrations (1-5/z/ml); higher concentrations blocked twitch responses more rapidly, but also resulted in dir ~et effects on muscle fibres, as revealed by slow contractures and a loss in sensitivity to KCl-induced depolarization. Vipera russelli (Russell's viper) venom from Thailand (10-20 pg/ml) also blocked neuromuscular transmission, but only produced small contractures at higher concentrations (100/zg/ml). The other venoms did not have selective effects on neuromuscular transmission. Echis carinatus (carpet viper) venom from Iran and Mali (100-200/tg/ml) and Crotalus atrox (Western diamondback rattlesnake from U.S.A.) venom (10-100 pg/ml) induced eontraetures and blocked responses to cholinergic stimulation and to KCI. Venoms of Bothrops atrox asper (Fer-de-lance from Costa Rica) and Trimeresurus flavoviridis (Okinawa habu from Japan) slowly produced partial block of all forms of stimulation after preparations were exposed to 50-100 ~ag/ml. These effects are consistent ,,~th the cl/nical symptoms after envenomation by these snakes. We conclude that the chick biventer cervicis preparation can be used as a simple in oitro assay to determine the potential neurotoxic and myotoxic effects of snake venoms. It could also be used to test the neutralising potency of antivenom preparations. References Ginsborg, B.L. and Warriner, J., 1960, Br. J. Pharmac. Chemother. 15, 410. Th~ston, R.D.G. ~_ndReid, H.A., 1983, Bull. WHO 61, 949. WHO, 1981, Progress in the Characterization of Venoms and Sta:'_~r~ization of Antivenom~, WHO, Geneva.