McNamara M K, Wiley J S
Am J Physiol. 1986 Jan;250(1 Pt 1):C26-31. doi: 10.1152/ajpcell.1986.250.1.C26.
Ca2+ influx was measured into human erythrocytes in which efflux was blocked by either introduction of an intracellular Ca2+ chelator, introduction of the Ca2+ chelator followed by ATP depletion, or depletion of the Ca2+ pump cofactors ATP and Mg2+. The Ca2+ influx under all three conditions was 14-20 mumol . 1 cells-1 . h-1, which is an order of magnitude higher than the influx previously reported for cells depleted of either ATP or Mg2+ separately. The difference between the two values was explained by the finding of substantial Ca2+ efflux from the Ca2+-loaded ATP-depleted cells, whereas this efflux was insignificant from cells loaded with quin 2 and then ATP depleted. Under these latter conditions Ca2+ influx estimates the unidirectional permeability to this cation. Studies using this technique showed that Ca2+ influx was the same in media of isotonic sodium, potassium, lithium, choline, or magnesium chlorides. Moreover the dependence of Ca2+ influx on external Ca2+ concentration was well described by the sum of saturable and nonsaturable (linear) components.
在人红细胞中测量Ca2+内流，其中通过引入细胞内Ca2+螯合剂、引入Ca2+螯合剂后耗尽ATP或耗尽Ca2+泵辅因子ATP和Mg2+来阻断外流。在所有这三种条件下，Ca2+内流为14 - 20 μmol·1细胞-1·h-1，这比之前分别报道的耗尽ATP或Mg2+的细胞的内流高一个数量级。这两个值之间的差异是由以下发现解释的：从加载Ca2+的ATP耗尽细胞中有大量Ca2+外流，而从加载喹啉2然后耗尽ATP的细胞中这种外流不明显。在这些后一种条件下，Ca2+内流估计了对该阳离子的单向通透性。使用该技术的研究表明，在等渗氯化钠、氯化钾、氯化锂、氯化胆碱或氯化镁介质中，Ca2+内流是相同的。此外，Ca2+内流对外界Ca2+浓度的依赖性可以通过饱和和非饱和（线性）成分的总和很好地描述。
