de Laat W S, Bluemink J G
J Cell Biol. 1974 Mar;60(3):529-40. doi: 10.1083/jcb.60.3.529.
The electrical membrane potential (E(m)) and electrical membrane resistance (R(m)) were measured continuously during the first cleavage of Xenopus eggs, using intracellular microelectrodes. A sharp hyperpolarization of E(m) and decrease in R(m) can be observed from 6 to 8 min after the onset of cleavage. This moment coincides with the onset of the insertion of new membrane (Bluemink and de Laat, 1973) leading to the formation of the interblastomeric membrane during normal cleavage. Removal of the vitelline membrane or exposure to cytochalasin B (CCB) leads to exposure of the entire surface area of the membrane newly formed during cleavage. These conditions allow for a direct measurement of the permeability properties of the new membrane. It was found that under these conditions E(m) reaches values about 3 times more negative and R(m) reaches values about 1.5-3 times smaller than during normal cleavage. The extent of reduction of R(m) can be correlated with the surface area of the newly formed membrane. We conclude that the new membrane has different ionic permeability properties than the pre-existing membrane (most probably a relatively high permeability for K(+) ions). Its mean specific resistance is 1-2 kOmega.cm(2), as against 74 kOmega.cm(2) for the pre-existing membrane. No influence of CCB on the permeability properties of the pre-existing or new membrane could be detected.
使用细胞内微电极，在非洲爪蟾卵第一次卵裂期间连续测量其电膜电位（E(m)）和电膜电阻（R(m)）。在卵裂开始后6至8分钟，可以观察到E(m)急剧超极化，R(m)降低。这个时刻与新膜插入的开始时间一致（Bluemink和de Laat，1973），在正常卵裂过程中会导致形成卵裂球间膜。去除卵黄膜或暴露于细胞松弛素B（CCB）会导致卵裂期间新形成的膜的整个表面积暴露。这些条件使得能够直接测量新膜的通透性特性。结果发现，在这些条件下，E(m)达到的值比正常卵裂期间负约3倍，R(m)达到的值比正常卵裂期间小约1.5至3倍。R(m)的降低程度与新形成膜的表面积相关。我们得出结论，新膜具有与先前存在的膜不同的离子通透性特性（很可能对K(+)离子具有相对较高的通透性）。其平均比电阻为1至2 kΩ·cm²（2），而先前存在的膜为74 kΩ·cm²（2）。未检测到CCB对先前存在的膜或新膜的通透性特性有影响。
