Baker P F, Foster R F, Gilbert D S, Shaw T I
J Physiol. 1971 Dec;219(2):487-506. doi: 10.1113/jphysiol.1971.sp009674.
The sodium efflux from perfused squid giant axons has been studied using radioactive sodium, and the sufficient conditions for the maintenance of a potassium- and ouabain-sensitive sodium efflux have been established. The following were found.1. Axons extruded and then perfused with their own axoplasm had a sodium efflux which was sensitive to cyanide, potassium and ouabain and was thus similar to the efflux from intact axons.2. A method for replacing natural axoplasm into fibres previously perfused with artificial axoplasm was developed and used to establish an artificial perfusate that was not irreversibly toxic.3. Short perfusion (5 min) with a variety of artificial perfusates was then found to give fibres which had potassium- and ouabain-sensitive sodium effluxes when ATP was present in the perfusate.4. In the absence of ATP the sodium efflux was small and relatively insensitive to both external potassium and to ouabain.5. With ADP in the perfusate, fibres gave a sodium efflux which was ouabain-sensitive but was little affected by the removal of external potassium from the sodium-rich sea water bathing the fibres.6. The perfused fibres differed from intact fibres in having large ouabain-insensitive sodium effluxes.7. After very long perfusions (40-90 min), with the simple media containing ATP, the rate constant for sodium efflux from the fibres tended to be large and was relatively insensitive to potassium or to ouabain.8. Fibres refilled with natural axoplasm after long perfusion showed increased sensitivity to external potassium; refilled with dispersed axoplasm the sodium efflux tended to become very large.9. After very long perfusions with artificial axoplasms containing ATP, a potassium- and ouabain-sensitive sodium efflux was found to persist provided that dextran was present and the total osmotic pressure and the hydrostatic pressure of the perfusate were controlled. Under these conditions the sodium efflux resembled that from briefly perfused fibres. The necessary and sufficient conditions for the maintenance of sodium transport by perfused giant axons are discussed.
利用放射性钠对灌注乌贼巨大轴突的钠外流进行了研究，并确定了维持对钾和哇巴因敏感的钠外流的充分条件。发现如下：
挤压轴突然后用其自身轴浆灌注，其钠外流对氰化物、钾和哇巴因敏感，因此与完整轴突的外流相似。
开发了一种将天然轴浆替换到先前用人工轴浆灌注的纤维中的方法，并用于建立一种无不可逆毒性的人工灌注液。
随后发现，用各种人工灌注液进行短时间灌注（5分钟），当灌注液中存在ATP时，纤维具有对钾和哇巴因敏感的钠外流。
在没有ATP的情况下，钠外流很小，并且对外部钾和哇巴因都相对不敏感。
当灌注液中有ADP时，纤维的钠外流对哇巴因敏感，但从富含钠的海水浴中去除外部钾对其影响不大。
灌注的纤维与完整纤维的不同之处在于，它们具有大量对哇巴因不敏感的钠外流。
在非常长时间的灌注（40 - 90分钟）后，使用含有ATP的简单培养基，纤维的钠外流速率常数往往很大，并且对钾或哇巴因相对不敏感。
长时间灌注后用天然轴浆重新填充的纤维对外部钾的敏感性增加；用分散的轴浆重新填充后，钠外流往往变得非常大。
在使用含有ATP的人工轴浆进行非常长时间的灌注后，发现只要存在右旋糖酐并且控制灌注液的总渗透压和静水压力，对钾和哇巴因敏感的钠外流就会持续存在。在这些条件下，钠外流类似于短时间灌注纤维的钠外流。讨论了灌注巨大轴突维持钠转运的必要和充分条件。
