Basu A, Gomes A, Gomes A, Dasgupta S C, Lahiri S C
Department of Pharmacology, School of Tropical Medicine, Calcutta, India.
Indian J Exp Biol. 1990 May;28(5):451-4.
Toxin-L a lethal neuromuscular blocking agent was isolated from the venom of the scorpion, Lychas laevifrons (Pocock), by the CM-cellulose ion-exchange chromatography. It was a homogenous, thermolabile and low molecular weight protein. The toxin produced irreversible blockade of indirect stimulation induced twitch responses on innervated rat phrenic nerve-diaphragm and chick biventer cervicis preparation. The toxin did not produce any contractile response on toad rectus abdominis muscle preparation. On chronically denervated rat diaphragm, the toxin failed to alter the responses induced by direct stimulation, exogenous acetylcholine, potassium chloride and caffeine. Acetylcholine and carbachol induced contractions on isolated chick biventer cervicis remained unaltered by the toxin. Neostigmine failed to alter toxin induced neuromuscular blockade on innervated rat diaphragm. The toxin released a significant amount of acetylcholine from innervated rat diaphragm. It may be concluded that the toxin acts presynaptically through the release of acetylcholine, thereby producing neuromuscular blockade.
通过CM - 纤维素离子交换色谱法从蝎子Lychas laevifrons（波科克）的毒液中分离出一种致死性神经肌肉阻滞剂——毒素 - L。它是一种均质、热不稳定且分子量低的蛋白质。该毒素对受神经支配的大鼠膈神经 - 膈肌和鸡颈二腹肌标本的间接刺激诱发的抽搐反应产生不可逆的阻滞作用。该毒素对蟾蜍腹直肌标本未产生任何收缩反应。在长期去神经支配的大鼠膈肌上，该毒素未能改变直接刺激、外源性乙酰胆碱、氯化钾和咖啡因所诱发的反应。乙酰胆碱和卡巴胆碱在离体鸡颈二腹肌上诱发的收缩不受该毒素影响。新斯的明未能改变该毒素对受神经支配的大鼠膈肌所诱发的神经肌肉阻滞作用。该毒素从受神经支配的大鼠膈肌中释放出大量乙酰胆碱。可以得出结论，该毒素通过释放乙酰胆碱在突触前起作用，从而产生神经肌肉阻滞。
