Blatter L A, McGuigan J A
Physiologisches Institut, Universität Bern, Schweiz.
Magnesium. 1988;7(3):154-65.
Determination of intracellular free magnesium [( Mg]i) with ion-selective Mg microelectrodes filled with the neutral carrier ETH 1117 is critically dependent on the values taken for K and Na in the calibrating solutions, for intracellularly the Mg microelectrodes also respond to these ions. This study was designed to test the influence of K and Na on the measured [Mg]i in ferret ventricular muscle. To estimate the effect of these ions, two methods were used: calculation based on the Nicolsky-Eisenman equation and calibration of the electrodes in solutions containing various concentrations of K and Na. Selectivity coefficients were measured for K and Na by the fixed interference method. While the Nicolsky-Eisenman equation could describe the behavior of an electrode in a given calibrating solution, the effects of changes in either the concentration of K and/or Na could not be predicted by the equation. Comparison between calibrating solutions containing the mean values for K and Na and calibrating solutions containing the lowest measured values for K and Na showed that the mean [Mg]i in ferret ventricle would increase from 0.4 to 0.9 mmol/l. A critical appraisal of the literature values for [Mg]i in muscle tissue suggests that values over 2 mmol/l were either unphysiological or too high for methodological reasons.
用填充中性载体ETH 1117的离子选择性镁微电极测定细胞内游离镁([Mg]i)，严重依赖于校准溶液中钾和钠所采用的值，因为在细胞内镁微电极也对这些离子有反应。本研究旨在测试钾和钠对雪貂心室肌中所测[Mg]i的影响。为评估这些离子的作用，使用了两种方法：基于尼科尔斯基-艾森曼方程进行计算，以及在含有不同浓度钾和钠的溶液中对电极进行校准。通过固定干扰法测量了钾和钠的选择性系数。虽然尼科尔斯基-艾森曼方程可以描述电极在给定校准溶液中的行为，但该方程无法预测钾和/或钠浓度变化的影响。比较含有钾和钠平均值的校准溶液与含有所测钾和钠最低值的校准溶液表明，雪貂心室中的平均[Mg]i将从0.4 mmol/L增加到0.9 mmol/L。对肌肉组织中[Mg]i文献值的批判性评估表明，超过2 mmol/L的值要么不符合生理情况，要么由于方法学原因过高。
