用于细胞内应用的中性载体钠和钙选择性微电极。

Neutral carrier Na+- and Ca2+-selective microelectrodes for intracellular application.

作者信息

Dagostino M, Lee C O

出版信息

Biophys J. 1982 Dec;40(3):199-207. doi: 10.1016/S0006-3495(82)84475-5.

DOI:10.1016/S0006-3495(82)84475-5

PMID:7183334

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1328996/

Abstract

Na+- and Ca2+-selective microelectrodes were made with Simon's neutral carrier ETH 227 and ETH 1001, respectively, and their properties were studied for intracellular application. The kNaK (selectivity coefficient for Na+ with respect to K+) values of the Na+-selective microelectrodes were in the range of 0.01-0.02, which is comparable to those of recessed-tip Na+-selective glass microelectrodes. The kNaMg values of the microelectrodes were approximately 0.005 so that the interference by intracellular Mg2+ levels could be negligible. The kNaCa values were approximately 2 and the Na+-selective microelectrodes were more selective to Ca2+ than Na+. This indicates that their intracellular application requires special care to handle Ca2+ interference under certain conditions. The kNaK, kNaMg, and kNaCa values did not depend significantly on the methods used for their determination or on the ion activity levels tested. The Nicolsky equation described well the microelectrode potentials in the mixed solutions of NaCl (1-100 mM) and KCl. Potential and resistance of the microelectrodes were stable for a long period and their response time was fast. The results indicate that the Na+-selective microlectrodes are suitable for measurements of intracellular Na ion activities. Ca2+-selective microelectrode potentials at Ca2+ concentrations lower than 10(-4) M changed significantly for the first 2-3 h and then became fairly stable. The rate of the potential change was dependent on the column length of the Ca2+-selective liquid filled. Potentials of the microelectrodes varied from 10-20 mV for Ca2+ between 10(-7) and 10(-6) M concentrations, which may be the cytosolic free-Ca2+ range. With the Ca2+ concentrations greater than 10(-6) M, the microelectrodes had potential changes of approximately 30 mV or greater for a tenfold change in Ca2+ concentration. The kCaK and kCaNa values were in the ranges of 10(-5)-10(-6) and 10(-4)-10(-5), respectively. The kCaMg values were approximately 10(-7). The results show that the Ca2+-selective microelectrodes can be used for measurements of cytosolic Ca ion activities.

摘要

分别使用西蒙中性载体ETH 227和ETH 1001制作了Na⁺和Ca²⁺选择性微电极，并研究了它们在细胞内应用时的特性。Na⁺选择性微电极的kNaK（Na⁺对K⁺的选择性系数）值在0.01 - 0.02范围内，这与凹陷尖端Na⁺选择性玻璃微电极的值相当。微电极的kNaMg值约为0.005，因此细胞内Mg²⁺水平的干扰可忽略不计。kNaCa值约为2，且Na⁺选择性微电极对Ca²⁺的选择性高于对Na⁺的选择性。这表明在某些条件下，它们在细胞内的应用需要特别注意处理Ca²⁺干扰。kNaK、kNaMg和kNaCa值并不显著依赖于用于测定它们的方法或所测试的离子活性水平。尼科尔斯基方程很好地描述了NaCl（1 - 100 mM）和KCl混合溶液中的微电极电位。微电极的电位和电阻在很长一段时间内是稳定的，并且它们的响应时间很快。结果表明，Na⁺选择性微电极适用于测量细胞内Na⁺离子活性。在Ca²⁺浓度低于10⁻⁴ M时，Ca²⁺选择性微电极电位在前2 - 3小时内变化显著，然后变得相当稳定。电位变化速率取决于Ca²⁺选择性填充液的柱长。对于浓度在10⁻⁷至10⁻⁶ M之间的Ca²⁺，微电极电位在10 - 20 mV之间变化，这可能是胞质游离Ca²⁺的范围。当Ca²⁺浓度大于10⁻⁶ M时，Ca²⁺浓度每变化10倍，微电极电位变化约30 mV或更大。kCaK和kCaNa值分别在10⁻⁵ - 10⁻⁶和10⁻⁴ - 10⁻⁵范围内。kCaMg值约为10⁻⁷。结果表明，Ca²⁺选择性微电极可用于测量胞质Ca²⁺离子活性。