鲎腹侧光感受器中的电压依赖性电导。
Voltage-dependent conductances in Limulus ventral photoreceptors.
作者信息
Lisman J E, Fain G L, O'Day P M
出版信息
J Gen Physiol. 1982 Feb;79(2):187-209. doi: 10.1085/jgp.79.2.187.
The voltage-dependent conductances of Limulus ventral photoreceptors have been investigated using a voltage-clamp technique. Depolarization in the dark induces inward and outward currents. The inward current is reduced by removing Na+ or Ca2+ and is abolished by removing both ions. These results suggest that both Na+ and Ca2+ carry voltage-dependent inward current. Inward current is insensitive to tetrodotoxin but is blocked by external Ni2+. The outward current has a large transient component that is followed by a smaller maintained component. Intracellular tetraethylammonium preferentially reduces the maintained component, and extracellular 4-amino pyridine preferentially reduces the transient component. Neither component is strongly affected by removal of extracellular Ca2+ or by intracellular injection of EGTA. It is concluded that the photoreceptors contain at least three separate voltage-dependent conductances: 1) a conductance giving rise to inward currents; 2) a delayed rectifier giving rise to maintained outward K+ current; and 3) a rapidly inactivating K+ conductance similar to the A current of molluscan neurons.
利用电压钳技术研究了鲎腹侧光感受器的电压依赖性电导。在黑暗中去极化会诱导内向和外向电流。去除Na⁺或Ca²⁺会使内向电流减小，同时去除这两种离子则内向电流消失。这些结果表明，Na⁺和Ca²⁺都携带电压依赖性内向电流。内向电流对河豚毒素不敏感，但会被细胞外的Ni²⁺阻断。外向电流有一个较大的瞬态成分，随后是一个较小的持续成分。细胞内四乙铵优先降低持续成分，而细胞外4-氨基吡啶优先降低瞬态成分。去除细胞外Ca²⁺或细胞内注射乙二醇双四乙酸（EGTA）对这两个成分的影响都不大。得出的结论是，光感受器至少包含三种独立的电压依赖性电导：1）一种产生内向电流的电导；2）一种延迟整流器，产生持续的外向K⁺电流；3）一种快速失活的K⁺电导，类似于软体动物神经元的A电流。
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