Active transport of potassium by the cecropia midgut. VI. Microelectrode potential profile.
Active transport of potassium by the cecropia midgut. VI. Microelectrode potential profile.
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天蚕中肠主动转运钾。
DOI：
10.1242/jeb.50.1.169
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发表时间：
1969
期刊：
影响因子：
--
通讯作者：
W. Harvey
中科院分区：
文献类型：
--
作者：
J. Wood;P. Farrand;W. Harvey
1. 当微电极从血液侧穿过惜古比天蚕（Hyalophora cecropia）离体中肠推进时所记录到的电位曲线由负平台组成，随后是一个大幅正向阶跃达到完整的中肠电位。
2. 缺氧会使正向阶跃和中肠电位均降低；负平台不受影响。
3. 血液侧溶液中钾浓度的变化会影响负平台和中肠电位；大幅正向阶跃基本保持不变。
4. 从这些结果可以得出结论：正向阶跃可能是由生电钾泵产生的，而负向阶跃是由于钾平衡电位。
5. 负电位和正电位的离散且独立的性质表明，有两个屏障将一个“中肠”隔室与两种浸泡溶液分隔开来。
6. 据推测，上皮细胞是电位曲线负值的部位，因此它们构成了“中肠”隔室。这种解释意味着钾平衡电位出现在基底细胞膜上，而生电泵电位出现在上皮细胞的顶质膜上。
7. 对这些结果最保守的解释是，生电钾泵位于上皮细胞顶质膜内或其上的某个位置。
1. The potential profile recorded as a microelectrode is advanced from the blood side through the isolated midgut of Hyalophora cecropia consists of negative plateaus followed by a large positive step to the full midgut potential. 2. Oxygen deprivation diminishes both the positive step and the midgut potential; the negative plateaus are not affected. 3. Changes in the potassium concentration in the blood-side solution affect both the negative plateaus and the midgut potential; the large positive step remains about the same. 4. From these results it is concluded that the positive step is probably produced by the electrogenic potassium pump and that the negative steps are due to a potassium equilibrium potential. 5. The discrete and independent nature of the negative and positive potentials argues that there are two barriers separating a ‘midgut’ compartment from the two bathing solutions. 6. It is inferred that the epithelial cells are the site of the profile negativity and therefore that they constitute the ‘midgut’ compartment. This interpretation implies that the potassium equilibrium potential appears across the basal cell membranes and that electrogenic pump potential appears across the apical plasma membranes of the epithelial cells. 7. The most conservative interpretation of these results is that the electrogenic potassium pump is located somewhere in or on the apical plasma membrane of the epithelial cells.