Time and voltage windows for reversing the electrical block to fertilization.
Time and voltage windows for reversing the electrical block to fertilization.
复制标题
将电块反转至受精的时间和电压窗口。
DOI：
10.1073/pnas.81.5.1436
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发表时间：
1984
影响因子：
11.1
通讯作者：
R. Steinhardt
中科院分区：
文献类型：
--
作者：
S. Shen;R. Steinhardt
海胆卵受精的电阻滞可以通过非常短暂的内负卵膜电位来克服。膜电位被钳制在+15 mV的红点绿绒螯蟹卵不能受精。如果膜电位在短时间内被复极化到内部负电压，卵子就可以成功受精。通过改变这些短暂的内部负性周期的持续时间和电压，我们发现了受精过程中电敏感步骤的三个一般特性。首先，在内部正电压下成为速率限制的膜电位阶跃可以在内部负电压的几毫秒内启动（在-60 mV下为30-60毫秒）。其次，在电敏感步骤完成时，还有其他可能具有较慢时间常数的电位无关步骤，因为负性的持续时间作为成对脉冲而不是单个长脉冲施加更有效。第三，由于成对脉冲之间的间隔可能比有效单脉冲的持续时间长几倍，因此由内部负性建立的允许状态比由内部正性建立的非允许状态更快。在这些电压钳位的鸡蛋中，从成功完成电敏感步骤到下一个可识别的激活迹象的间隔大约为几秒钟，并且变化很大。
The electrical block to fertilization of sea urchin eggs can be overcome by very brief periods of inside-negative egg membrane potential. Lytechinus pictus eggs whose membrane potentials have been clamped at +15 mV cannot be fertilized. If the membrane potential is repolarized to inside-negative voltages for a brief interval, the egg can be successfully fertilized. By varying the duration and voltage of these brief periods of inside negativity, we have uncovered three general properties of the electrically sensitive step in fertilization. First, a membrane-potential step that becomes rate limiting at inside-positive voltages can be initiated within a few milliseconds of inside negativity (30-60 msec at -60 mV). Second, at the time that the electrically sensitive step is being completed, there are other potential-independent steps with probably slower time constants because the duration of negativity was more effective applied as paired pulses rather than a single long pulse. Third, the permissive state is more quickly established by inside negativity than the nonpermissive state is established by inside positivity because the interval between paired pulses could be a few times longer than the effective single pulse in duration. In these voltage-clamped eggs the intervals from the successful completion of the electrically sensitive step to the next identifiable signs of activation were on the order of several seconds and highly variable.