Resting membrane potential and the current-voltage relation were measured in crayfish giant axons bathed in various potassium solutions with and without ouabain. 2. Ouabain caused a depolarization of the membrane at each [K]o used but did not affect membrane resistance. 3. The ouabain-sensitive transport current was least (3 microamperemeter/cm2) in 0 mM [K]o and greatest (7 microamperemeter/cm2) in 16.2 and 21.6 mM [K]o. 4. The assumption was made an some indirect evidence presented that axons equilibrated in various potassium solutions maintain constant internal sodium and potassium concentrations for up to 3 h. 5. On the basis of this assumption, the apparent ratio of coupled Na : K transport was calculated. It was found to be least (-1.3/1) in 0 mM [K]o and to approach infinity in 16.2 and 21.6 mM [K]o. 6. The data indicate that the apparent variability of the Na : K exchange ratio likely represents an intrinsic property of the exchange mechanism and is less likely to be explained by a fixed-ratio coupled Na : K transport operating in parallel with electro-neutral Na : Na or K : K exchange.
摘要
在含有和不含有哇巴因的各种钾溶液中浸泡的小龙虾巨轴突中测量静息膜电位和电流-电压关系。2. 在所用的每种[K]o浓度下，哇巴因都会引起膜去极化，但不影响膜电阻。3. 哇巴因敏感的转运电流在0 mM [K]o时最小（3微安/平方厘米），在16.2和21.6 mM [K]o时最大（7微安/平方厘米）。4. 基于一些间接证据做出假设，即在各种钾溶液中平衡的轴突在长达3小时内保持恒定的内部钠和钾浓度。5. 基于该假设，计算了耦合的Na:K转运的表观比率。发现在0 mM [K]o时最小（-1.3/1），在16.2和21.6 mM [K]o时接近无穷大。6. 数据表明，Na:K交换比率的表观变异性可能代表交换机制的固有特性，不太可能由与电中性Na:Na或K:K交换并行运行的固定比率耦合Na:K转运来解释。
