Intracellular pH in early Xenopus embryos: its effect on current flow between blastomeres.
Intracellular pH in early Xenopus embryos: its effect on current flow between blastomeres.
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早期非洲爪蟾胚胎的细胞内 pH 值：其对卵裂球之间电流的影响。
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
A. Warner
中科院分区：
文献类型：
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作者：
L. Turin;A. Warner
1.电生理学技术用于监测非洲爪蟾胚胎在4细胞和早期囊胚发育阶段之间从一个细胞到下一个细胞的电流流动。使用pH敏感微电极测定细胞内pH和囊胚腔pH。2.静息细胞内pH为7.74+/-0.02（S.E.平均值，n = 29）;发育阶段之间没有系统性差异。囊胚腔pH值为8.4+/-0.06（S.E.平均值，n = 10）。细胞内缓冲液值为18 m-equiv。H+/pH单位/升。3.在用100%CO2平衡的碳酸氢盐缓冲的Holtfreter溶液处理的胚胎中，细胞内pH降至6.3+/-0.17（S.D.，n = 8）。膜电位下降，输入电阻增加。对膜电位和输入电阻的影响大小各不相同。4.从32细胞阶段开始，当细胞内pH值降至6.5以下时，从一个细胞到下一个细胞的电流被消除;这种效应起效迅速，完全可逆。在卵裂阶段的发展，降低细胞内的pH值与CO2没有影响电流从细胞到细胞。5.细胞内的pH值和电流之间的关系从细胞到细胞是S形的，覆盖0.2和0.4 pH单位。电流完全消失时的pH值范围为6.85至6.4。6.在5.8 - 7.5范围内的胚外pH值变化对任何测量参数均无影响。7.我们得出结论，降低细胞内pH值会增加两种非连接性连接膜的阻力。这些数据不允许我们提取pH结电导关系。8.细胞内pH值的变化可能为研究成体器官和早期胚胎中细胞间直接通讯的功能作用提供了有用的工具。
1. Electrophysiological techniques were used to monitor the flow of electric current from one cell to the next in Xenopus laevis embryos between the 4‐cell and early blastula stages of development. Intracellular pH and blastocoel pH were determined using pH‐sensitive micro‐electrodes. 2. The resting intracellular pH was 7.74+/‐0.02 (S.E. of mean, n = 29); there were no systematic differences between developmental stages. Blastocoel cavity pH was 8.4+/‐0.06 (S.E. of mean, n = 10). The intracellular buffer value was 18 m‐equiv. H+/pH unit per litre. 3. In embryos treated with bicarbonate buffered Holtfreter solution equilibrated with 100% CO2 the intracellular pH fell to 6.3+/‐0.17 (S.D., n = 8). The membrane potential fell and the input resistance increased. The size of the effect on membrane potential and input resistance varied. 4. From the 32‐cell stage onwards current flow from one cell to the next was abolished when the intracellular pH fell to below 6.5; the effect was rapid in onset and completely reversible. At cleavage stages of development lowering intracellular pH with CO2 had no effect on current flow from cell to cell. 5. The relationship between intracellular pH and current flow from cell to cell was sigmoid and covered between 0.2 and 0.4 pH units. The pH at which current flow was completely abolished ranged from 6.85 to 6.4. 6. Alterations in extraembryonic pH over the range 5.8‐7.5 had no effect on any parameter measured. 7. We conclude that lowering the intracellular pH increases the resistance of both non‐junctional junctional membranes. The data do not allow us to extract the pH junctional conductance relationship. 8. Variations in intracellular pH may provide a useful tool for the study of the functional role of direct cell to cell communication in both adult organs and early embryos.