Characterization of two Bunodosoma granulifera toxins active on cardiac sodium channels

被引:25
作者
Goudet, C
Ferrer, T
Galán, L
Artiles, A
Batista, CFV
Possani, LD
Alvarez, J
Aneiros, A
Tytgat, J
机构
[1] Katholieke Univ Leuven, Toxicol Lab, B-3000 Louvain, Belgium
[2] Inst Cardol & Cirugia Cardiovasc, Havana 10600, Cuba
[3] Univ Nacl Autonoma Mexico, Dept Mol Recognit & Struct Biol, Cuernavaca 62210, Morelos, Mexico
[4] Inst Oceanol, Havana 10600, Cuba
关键词
sea anemone toxin; voltage-gated sodium channels; inactivation; ionic selectivity; cardiotoxin; neurotoxin;
D O I
10.1038/sj.bjp.0704361
中图分类号
R9 [药学];
学科分类号
1007 ;
摘要
1 Two sodium channel toxins, BgII and BgIII, have been isolated and purified from the sea anemone Bunodosoma granulifera. Combining different techniques, we have investigated the electrophysiological properties of these toxins. 2 We examined the effect of BgII and BgIII oil rat ventricular strips. These toxins prolong action potentials with EC50 values of 60 and 660 nm and modify the resting potentials. 3 The effect on Na+ currents in rat cardiomyocytes was studied using the patch-clamp technique. BgII and BgIII slow the rapid inactivation process and increase the current density with EC50 values of 58 and 78 nm, respectively. 4 On the cloned hH1 cardiac Na+ channel expressed in Xenopus laevis oocytes, BgII and BgIII slow the inactivation process of Na+ currents (respective EC50 values of 0.38 and 7.8 mum), shift the steady-state activation and inactivation parameters to more positive potentials and the reversal potential to more negative potentials. 5 The amino acid sequences of these toxins are almost identical except for an asparagine at position 16 in BgII which is replaced by an aspartic acid in BgIII. In all experiments, BgII was more potent than BgIII suggesting that this conservative residue is important for the toxicity of sea anemone toxins. 6 We conclude that BgII and BgIII, generally known as neurotoxins, are also cardiotoxic and combine the classical effects of sea anemone Na+ channels toxins (slowing of inactivation kinetics, shift of steady-state activation and inactivation parameters) with a striking decrease on the ionic selectivity of Na+ channels.
引用
收藏
页码:1195 / 1206
页数:12
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