An Examination of the Neutralization of In Vitro Toxicity of Chinese Cobra () Venom by Different Antivenoms.

The Chinese Cobra () is an elapid snake of major medical importance in southern China. We describe the in vitro neurotoxic, myotoxic, and cytotoxic effects of venom, as well as examining the efficacy of three Chinese monovalent antivenoms ( antivenom, antivenom and antivenom) and an Australian polyvalent snake antivenom. In the chick biventer cervicis nerve-muscle preparation, venom (1-10 µg/mL) abolished indirect twitches in a concentration-dependent manner, as well as abolishing contractile responses to exogenous acetylcholine chloride (ACh) and carbamylcholine chloride (CCh), indicative of post-synaptic neurotoxicity. Contractile responses to potassium chloride (KCl) were also significantly inhibited by venom indicating myotoxicity. The prior addition of Chinese antivenom (0.75 U/mL) or Australian polyvalent snake antivenom (3 U/mL), markedly attenuated the neurotoxic actions of venom (3 µg/mL) and prevented the inhibition of contractile responses to ACh, CCh, and KCl. The addition of Chinese antivenom (0.75 U/mL) or Australian polyvalent antivenom (3 U/mL) at the t time point after the addition of venom (3 µg/mL), partially reversed the inhibition of twitches and significantly reversed the venom-induced inhibition of responses to ACh and CCh, but had no significant effect on the response to KCl. Venom (30 µg/mL) also abolished direct twitches in the chick biventer cervicis nerve-muscle preparation and caused a significant increase in baseline tension, further indicative of myotoxicity. antivenom (4 U/mL) prevented the myotoxic effects of venom (30 µg/mL). However, antivenom (24 U/mL), antivenom (8 U/mL) and Australian polyvalent snake antivenom (33 U/mL) were unable to prevent venom (30 µg/mL) induced myotoxicity. In the L6 rat skeletal muscle myoblast cell line, venom caused concentration-dependent inhibition of cell viability, with a half maximal inhibitory concentration (IC) of 2.8 ± 0.48 μg/mL. antivenom significantly attenuated the cytotoxic effect of the venom, whereas Australian polyvalent snake antivenom was less effective but still attenuated the cytotoxic effects at lower venom concentrations. Neither antivenom or antivenom were able to prevent the cytotoxicity. This study indicates that Chinese monovalent antivenom is efficacious against the neurotoxic, myotoxic and cytotoxic effects of venom but the clinical effectiveness of the antivenom is likely to be diminished, even if given early after envenoming. The use of Chinese viper antivenoms (i.e., and antivenoms) in cases of envenoming by the Chinese cobra is not supported by the results of the current study.