Sun J J, Walker M J
Toxicon. 1986;24(3):233-45. doi: 10.1016/0041-0101(86)90149-2.
The cardiotoxic actions of southern Chinese cobra (Naja naja atra) venom have been investigated. Cardiotoxicity accounted for lethality of crude venom in anaesthetized rats and cardiotoxic polypeptides constituted the bulk of the venom when it was fractionated by CM-Sephadex chromatography. The cardiotoxic actions of these polypeptides were investigated in isolated cardiac tissue. Actions of cardiotoxins on rate, force and intracellular potentials occurred more readily in ventricular tissue and were reversible in all cardiac tissues. Bolus injections of cardiotoxins to perfused rat hearts produced profound changes in intracellular potentials, but such changes were reversed by 10 min after toxin wash-out. The changes included depolarization and loss of the fast phase (0) of the action potential. The loss of beating and contracture produced by cardiotoxins in isolated atria and ventricles showed such marked tachyphylaxis that toxicity was lost after 2-5 exposures. Both calcium and heparin ameliorated the cardiotoxic actions of cardiotoxins. Since the actions of cardiotoxin were partially selective for ventricular tissue, reversible, demonstrated tachyphylaxis and could be prevented, it is suggested that a specific molecular mechanism may be involved, rather than a non-specific action such as cell membrane destruction.
对中华眼镜蛇（舟山眼镜蛇）毒液的心脏毒性作用进行了研究。心脏毒性是粗毒液致使麻醉大鼠死亡的原因，当通过CM - 葡聚糖凝胶色谱法对毒液进行分级分离时，心脏毒性多肽构成了毒液的主要部分。在离体心脏组织中研究了这些多肽的心脏毒性作用。心脏毒素对心率、心肌收缩力和细胞内电位的作用在心室组织中更容易发生，并且在所有心脏组织中都是可逆的。向灌注的大鼠心脏推注心脏毒素会使细胞内电位发生深刻变化，但在毒素洗脱10分钟后这些变化会逆转。这些变化包括动作电位快速相（0相）的去极化和丧失。心脏毒素在离体心房和心室中引起的搏动丧失和挛缩表现出明显的快速耐受性，在2 - 5次暴露后毒性消失。钙和肝素均可减轻心脏毒素的心脏毒性作用。由于心脏毒素的作用对心室组织具有部分选择性、可逆性，表现出快速耐受性且可被预防，因此提示可能涉及一种特定的分子机制，而非诸如细胞膜破坏等非特异性作用。
