Goularte F C, Cruz-Höfling M A, Cogo J C, Gutiérrez J M, Rodrigues-Simioni L
Department of Pharmacology, Faculty of Medical Sciences, UNICAMP, Brazil.
Toxicon. 1995 May;33(5):679-89. doi: 10.1016/0041-0101(94)00178-b.
In the isolated mouse diaphragm preparation, Micrurus nigrocinctus venom produced a dose-dependent contracture and blockade of the contractile response to direct and indirect electrical stimulation of the muscle. This effect could not be completely reversed by repeated washing of the preparation nor by the addition of neostigmine or 3, 4-diaminopyridine. The observation that the direct blockade had to be preceded by indirect blockade together with the capacity for venom to prevent the ACh- but not the KCl-induced contractures in biventer cervicis and chronically denervated preparations strongly suggests a curarimimetic action for the venom. The temperature at which the experiment was performed greatly influenced the neuromuscular blocking and myotoxic actions of the venom and suggests that the venom component responsible for these effects is thermolabile. Both the neuromuscular blocking action and the myotoxicity of the venom could be prevented by a specific M. nigrocinctus antivenom regardless of whether this was added together with or after the venom. The muscle morphological changes induced by the venom were accompanied by a corresponding increase in the release of creatine kinase (CK) into the incubation medium. This release was, however, submaximal (35%) when compared to that induced by the detergent Triton X-100. In contrast to what has been demonstrated for other Micrurus venoms (M. frontalis, M. corallinus, M. lemniscatus and M. spixii), our results show that the myotoxic effect induced by M. nigrocinctus venom is important for the development of blockade of the muscle contractile response.
在离体小鼠膈肌制备实验中，黑环珊瑚蛇毒可产生剂量依赖性的挛缩，并阻断肌肉对直接和间接电刺激的收缩反应。通过反复冲洗标本，或添加新斯的明或3,4 -二氨基吡啶，均不能完全逆转这种效应。直接阻断必须先于间接阻断这一观察结果，以及毒液能够阻止二腹肌和长期去神经支配标本中乙酰胆碱诱导的挛缩，但不能阻止氯化钾诱导的挛缩，这强烈提示该毒液具有箭毒样作用。实验进行时的温度对毒液的神经肌肉阻断和肌毒性作用有很大影响，这表明负责这些效应的毒液成分是热不稳定的。无论在毒液添加前还是添加后加入黑环珊瑚蛇特异性抗蛇毒血清，均可预防毒液的神经肌肉阻断作用和肌毒性。毒液诱导的肌肉形态学变化伴随着肌酸激酶（CK）释放到孵育培养基中的相应增加。然而，与去污剂Triton X - 100诱导的释放相比，这种释放是次最大的（35%）。与其他珊瑚蛇毒液（M. frontalis、M. corallinus、M. lemniscatus和M. spixii）的情况不同，我们的结果表明，黑环珊瑚蛇毒诱导的肌毒性作用对于肌肉收缩反应阻断的发展很重要。
