平颏海蛇毒的毒理学研究

用CM-sephadex C-50柱层析,醋酸铵缓冲液洗脱,从平颏海蛇(Lapemis hardwickii)毒腺提取物中分得15个蛋白组分。其中2个有磷脂酶A_2活性,用免疫学方法证实为肌肉毒组分。其中10个是能作用于突触后膜的神经毒组分。肌肉毒的蛋白质含量约占粗毒蛋白质总量的32.2％。神经毒的蛋白质含量约占粗毒蛋白质总量的52.3％。神经毒的毒性比肌肉毒的毒性强。这些结果提示,平颏海蛇毒有肌肉毒和神经毒两种。神经毒是平颏海蛇毒的主要毒性成分。

The role of extracellular calcium in the effect of a snake venom Lys49-phospholipase A_(2) on water transport across epithelial membranes

ACLMT is a Lys49-phospholipase A2 myotoxin isolated from the venom of the Agkistrodon contortrix laticinctus snake. This study investigated the mechanisms involved in effect of ACLMT on membrane water permeability by examining the role of extracellular calcium and strontium in this effect. Water flow across the membrane was gravimetrically measured in bladder sac preparations. The decrease in extracellular calcium promoted a higher response of epithelium to ACLMT, suggesting that the extracellular calcium protects the membrane from the action of the toxin. No alteration in the effect of the toxin on water transport was observed when calcium was replaced by strontium, indicating that this effect is independent of its enzymatic activity. These findings may bring an important contribution towards the comprehension of the mechanisms involved in the effect of Lys49-phospholipase A2 myotoxins on water permeability of epithelial membranes, with implications for the understanding of renal toxicity.

蛇毒神经毒素和肌肉毒素研究进展

对蛇毒中神经毒素和肌肉毒素的分类、理化性质、结构及药理学活性进行了综述。当前研究表明,蛇毒神经毒素可分为3类:突触前神经毒素、突触后神经毒素和类神经毒素;前两者主要抑制运动终板处的神经肌肉传导,造成肌肉麻痹和呼吸衰竭;而后者可以阻断平滑肌收缩和离子通道,表现出类神经毒活性。蛇毒肌肉毒素主要分为3类:响尾蛇毒素、心脏毒素和肌肉毒PLA2;它们主要表现为破坏肌细胞膜,降解肌纤维,造成肌肉坏死。近年来,大量的蛇毒神经毒素和肌肉毒素的结构与功能得以确定,其在临床医学及研究领域中将有着重要的应用前景。随着在作用机制等方面研究的不断深入,蛇毒神经毒素和肌肉毒素的用途也将越来越广泛。