Thompson S, Knier J
Dev Biol. 1983 Sep;99(1):121-31. doi: 10.1016/0012-1606(83)90259-2.
Electrical activity in the fertilized egg of the tunicate Clavelina was studied with microelectrode recording and voltage clamp techniques. The resting potential could assume either of two stable values (approximately -70 or -30 mV) and could be shifted between these values by direct current stimulation. Spontaneous shifts between two stable resting potentials were also seen. Egg cells produced action potentials spontaneously and in response to depolarizing stimuli. Inward currents were carried by both Na and Ca ions and a prominent outward potassium current was seen with depolarization to voltages above -15 mV. The steady-state current-voltage relationship (I-V curve) of the membrane showed two voltages where the net membrane current equaled zero: approximately -35 and -70 mV. Between these two voltages, membrane current was inward and carried by noninactivating Na and Ca currents. Inward rectification, which was blocked by external Rb, occurred at voltages below -70 mV. The voltage dependence of inward rectification is thought by the authors to be important for establishing the more negative resting potential; it is also thought the presence of inward current which does not inactivate completely at voltages more negative than about -20 mV is an important determinant of the more depolarized resting potential.
利用微电极记录和电压钳技术研究了被囊动物海鞘受精卵的电活动。静息电位可以取两个稳定值中的任意一个（约 -70 或 -30 mV），并且可以通过直流刺激在这些值之间转换。也观察到了两个稳定静息电位之间的自发转换。卵细胞会自发产生动作电位，并且对去极化刺激有反应。内向电流由 Na 和 Ca 离子携带，当去极化到高于 -15 mV 的电压时，会出现明显的外向钾电流。膜的稳态电流 - 电压关系（I - V 曲线）显示出两个膜净电流等于零的电压：约 -35 和 -70 mV。在这两个电压之间，膜电流是内向的，由非失活的 Na 和 Ca 电流携带。内向整流在低于 -70 mV 的电压下发生，它被外部 Rb 阻断。作者认为内向整流的电压依赖性对于建立更负的静息电位很重要；还认为在比约 -20 mV 更负的电压下不完全失活的内向电流的存在是更去极化静息电位的一个重要决定因素。
