Murayama K, Lakshminarayanaiah N
J Membr Biol. 1977 Jul 14;35(3):257-83. doi: 10.1007/BF01869953.
Intracellular perfusion technique has been applied to the muscle fibers of the barnacle species, Balanus nubilus. In these fibers, generation and the form of the calcium spike was governed by the frequency of stimulation and intra- and extracellular calcium concentrations. Voltage-clamp experiments showed that the magnitude of the potassium outward current was controlled by the intracellular calcium concentration whose increase, nearly 10(3)-fold, raised the resting membrane conductance and the outward potassium current. On the other hand, application of 10 mM zinc ions inside the muscle fiber had no effect on either the resting potential or the outward potassium current but suppressed the early inward calcium current. Similarly, the inward calcium current was decreased by low concentration of sodium ions in the extracellular fluid only when its ionic strength was made low by substituting sucrose for the sodium salt. Measurement of outward current with the muscle fiber in calcium-free ASW solution and intracellularly perfused with several cationic solutions established the selectivity sequence TEA less than Cs less than Li less than Tris less than Rb less than Na less than K for the potassium channel.
细胞内灌注技术已应用于藤壶物种——巨藤壶的肌纤维。在这些肌纤维中，钙峰的产生及其形式受刺激频率以及细胞内和细胞外钙浓度的支配。电压钳实验表明，钾外向电流的大小受细胞内钙浓度的控制，细胞内钙浓度增加近10³倍，会提高静息膜电导和钾外向电流。另一方面，在肌纤维内施加10 mM锌离子对静息电位或钾外向电流均无影响，但会抑制早期内向钙电流。同样，只有当用蔗糖替代钠盐使细胞外液离子强度降低时，细胞外液中低浓度的钠离子才会使内向钙电流减小。在无钙人工海水（ASW）溶液中对肌纤维进行外向电流测量，并在细胞内灌注几种阳离子溶液，确定了钾通道的选择性顺序为：四乙铵（TEA）＜铯（Cs）＜锂（Li）＜三羟甲基氨基甲烷（Tris）＜铷（Rb）＜钠（Na）＜钾（K）。
