The wave of activation current in the egg of the medaka fish.
The wave of activation current in the egg of the medaka fish.
复制标题
青鳉鱼卵中的激活电流波。
DOI：
10.1016/0012-1606(87)90316-2
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发表时间：
1987
影响因子：
2.7
通讯作者：
Nuccitelli,R
中科院分区：
文献类型：
--
作者：
Nuccitelli,R
使用细胞外振动电极来测量内向电流的环形波，即激活电流，该电流以 10 μm/秒的速度穿过青鳉鱼 (Oryzias latipes) 的卵，从动物极的精卵融合部位传播到植物极。该激活波是由于 Na+、K+ 和 Ca2+ 电导的局部增加造成的，反映了这些离子通道的传播开放。最早的可检测电流在受精电位启动后20秒开始进入动物极，因此导致受精电位的第一个离子运动低于振动探针系统的分辨率。这些通道存在于动物和植物半球中，但动物半球的激活电流强度大约是动物半球的七倍。除了在受精点水流首先向内流动之外，在内向水流之前和之后都会有强度较小且分布在较大区域的向外水流。电流方向取决于外部Na+浓度，在更生理的10% NaCl-Yamamoto's Riger's溶液中，其方向反转为向外，显然是由K+外流携带的。在同样的低 Na+ 介质中提高外部 Ca2+ 会反转电流，使其再次向内流动，并增加波的传播速度，表明内向电流中存在 Ca2+ 成分。在该区域发生任何囊泡融合之前约 16 秒，电流进入卵子表面的给定区域。肌醇-1,4,5,-三磷酸的离子电渗疗法立即触发卵子激活，最小激活电荷为 0.6 nC。
An extracellular vibrating electrode was used to measure the ring-shaped wave of inward current, the activation current, that propagates at 10 μm/sec across the egg of the medaka fish,Oryzias latipes, from the site of sperm-egg fusion at the animal pole to the vegetal pole. This activation wave is due to a localized increase in the conductance to Na+, K+, and Ca2+and reflects the propagated opening of these ion channels. The earliest detectable current begins to enter the animal pole 20 secafterthe initiation of the fertilization potential, so the first ion movements responsible for the fertilization potential are below the resolution of the vibrating probe system. These channels are present in both the animal and vegetal hemispheres, but the magnitude of the activation current is about seven times greater in the animal hemisphere. An outward current of smaller magnitude and spread out over a larger area precedes and follows the inward current except at the point of fertilization where the current is first inward. The current direction is dependent on the external Na+concentration, and in the more physiological solution of 10% NaCl-Yamamoto's Riger's, its direction reverses to become outward, apparently carried by K+efflux. Raising the external Ca2+in this same low-Na+medium reverses the current so that it becomes inward again and increases the propagation velocity of the wave, suggesting a Ca2+component to the inward current. Current enters a given region on the egg's surface about 16 sec before any vesicle fusion occurs in that region. Iontophoresis of inositol-1,4,5,-trisphosphate immediately triggers egg activation with a minimum activating charge of 0.6 nC.