Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium.
Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium.
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昆虫上皮的基底外侧 K 通道。
DOI：
10.1085/jgp.87.3.443
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Lewis,SA
中科院分区：
文献类型：
--
作者：
Hanrahan,JW;Wills,NK;Phillips,JE;Lewis,SA
摘要用电流波动分析和微电极技术研究了昆虫后肠基底外侧膜钾通道。蝗虫直肠安装在Ussing型室含有无氯盐水和环磷酸腺苷（CAMP）。在短路条件下，通过升高血清[K]诱导跨上皮K电流。在这些条件下，将Ba添加到粘膜（管腔）侧没有影响;然而，丝氨酸Ba可逆地抑制短路电流（IK），增加跨上皮电阻（R1），并在I.的功率密度谱中添加洛伦兹分量。角频率与血清[Ba]之间存在非线性关系，这表明Ba与基底外侧通道结合的速率常数随[Ba]升高而增加。微电极实验表明，当加入Ba时，基底外侧膜超极化：膜电位的这种变化可以解释21 rfc与[Ba]如果外部Ba感知到约四分之三的基底外侧膜场，则存在这种关系。传统的微电极被用来确定transepithelially测量的电流噪声和基底外侧膜电导波动之间的对应关系，和离子敏感微电极被用来测量细胞内K活性（aK）。根据K跨基底外侧膜的净电化学势和由噪声分析计算的单通道电流之间的关系，我们估计基底外侧K通道的电导为-60 pS，并且每平方厘米组织面积有-1.8亿个通道。
ABSTRACT K channels in the basolateral membrane of insect hindgut were studied using current fluctuation analysis and microelectrodes. Locust recta were mounted in Ussing-type chambers containing Cl-free saline and cyclic AMP (CAMP). A transepithelial K current was induced by raising serosal [K] under short-circuit conditions. Adding Ba to the mucosal (luminal) side under these conditions had no effect; however, serosal Ba reversibly inhibited the short-circuit current (IK), increased transepithelial resistance (R,), and added a Lorentzian component to power density spectra of the I.. A nonlinear relationship between corner frequency and serosal [Ba] was observed, which suggests that the rate constant for Ba association with basolateral channels increased as [Ba] was elevated. Microelectrode experiments revealed that the basolateral membrane hyperpolarized when Ba was added: this change in membrane potential could explain the nonlinearity of the 21rfc vs.[Ba] relationship if external Ba sensed about three-quarters of the basolateral membrane field. Conventional microelectrodes were used to determine the correspondence between transepithelially measured current noise and basolateral membrane conductance fluctuations, and ion-sensitive microelectrodes were used to measure intracellular K activity (aK). From the relationship between the net electrochemical potential for Kacross the basolateral membrane and the single channel current calculated from noise analysis, we estimate that the conductance of basolateral K channels is-60 pS, and that there are-180 million channels per square centimeter of tissue area.