Noda M, Muramatsu I, Fujiwara M
Naunyn Schmiedebergs Arch Pharmacol. 1984 Aug;327(1):75-80. doi: 10.1007/BF00504995.
The effects of Goniopora toxin (GPT), isolated from the Goniopora species, on the action potential and membrane currents of bullfrog atrial muscle were studied using the double sucrose-gap method. GPT at concentrations above 10 nmol/l prolonged the duration of the action potential and sometimes induced arrhythmias. The prolongation was also induced in the presence of Ca channel blockers (Mn or verapamil). These effects were not reversed by continuous superfusion of GPT-free solution, but were rapidly antagonized by tetrodotoxin (1 mumol/l). The resting potential was not affected by GPT. Voltage clamp experiments revealed that sustained inward current flows following the fast sodium current upon depolarization, in the presence of GPT. The current was elicited by the toxin in Mn-treated fibers and abolished in the presence of TTX. The delayed outward current (Ix) was slightly reduced; the background K current (IK1), inward background current (Ib) and slow inward current (Islow) were not altered by GPT. These results suggest that GPT acts on sodium channels to give rise to a prolonged sodium current which is in turn responsible for the prolongation of the action potential.
利用双蔗糖间隙法研究了从角孔珊瑚属物种中分离出的角孔珊瑚毒素（GPT）对牛蛙心房肌动作电位和膜电流的影响。浓度高于10 nmol/l的GPT可延长动作电位的持续时间，有时还会诱发心律失常。在存在钙通道阻滞剂（锰或维拉帕米）的情况下也会出现这种延长。连续灌注不含GPT的溶液并不能逆转这些效应，但河豚毒素（1 μmol/l）可迅速拮抗这些效应。GPT对静息电位没有影响。电压钳实验表明，在存在GPT的情况下，去极化后在快速钠电流之后会有持续的内向电流流动。该电流由毒素在经锰处理的纤维中引发，并在存在TTX的情况下消失。延迟外向电流（Ix）略有降低；背景钾电流（IK1）、内向背景电流（Ib）和缓慢内向电流（Islow）不受GPT影响。这些结果表明，GPT作用于钠通道，产生延长的钠电流，进而导致动作电位延长。
