Krell H, Täfler M, Blaich G, Pfaff E
Hoppe Seylers Z Physiol Chem. 1984 Jan;365(1):59-71. doi: 10.1515/bchm2.1984.365.1.59.
As to functional consequences of Ca2+ uptake in isolated rat liver mitochondria, we simultaneously measured 3H2O and [14C]sucrose spaces, monovalent cation distribution, membrane potential and delta pH across the inner membrane, and [32P]phosphate and 45Ca2+ content in parallel incubations of different ionic composition. Without added Ca2+ and phosphate, mitochondrial matrix volume, membrane potential, and delta pH depended on the concentration and permeability of monovalent cations. Despite large differences in membrane potential, maximal Ca2+ uptake was identical under all conditions. Ca2+ uptake never provoked a volume change from which an osmotic active state of mitochondrial Ca2+ could be concluded. If matrix volume shrunk this could be totally accounted for by the loss of alkali ions exchanging for calcium ions. Even phosphate taken up in conjunction with Ca2+ was osmotically silent. Volume increases here occurring if K+ was permeabilized, solely resulted from K+ uptake, though this condition may give rise to irreversible mitochondrial damage with Ca2+ and phosphate release. As mitochondrial Ca2+ is bound, an electro-chemical equilibrium across the membrane is impossible for this ion. This has to be considered in any model describing equilibria of Ca2+ with mitochondria, though present models neglect this state of mitochondrial Ca2+.
关于分离的大鼠肝线粒体中Ca2+摄取的功能后果，我们在不同离子组成的平行孵育中同时测量了3H2O和[14C]蔗糖空间、单价阳离子分布、内膜两侧的膜电位和ΔpH，以及[32P]磷酸盐和45Ca2+含量。在不添加Ca2+和磷酸盐的情况下，线粒体基质体积、膜电位和ΔpH取决于单价阳离子的浓度和通透性。尽管膜电位存在很大差异，但在所有条件下最大Ca2+摄取量是相同的。Ca2+摄取从未引发体积变化，因此无法由此推断线粒体Ca2+的渗透活性状态。如果基质体积缩小，这完全可以由与钙离子交换的碱离子的损失来解释。即使与Ca2+一起摄取的磷酸盐在渗透方面也是无活性的。如果K+具有通透性时发生体积增加，这完全是由于K+摄取所致，尽管这种情况可能会导致Ca2+和磷酸盐释放，从而引起不可逆的线粒体损伤。由于线粒体Ca2+是结合的，因此该离子不可能在膜两侧达到电化学平衡。在任何描述Ca2+与线粒体平衡的模型中都必须考虑这一点，尽管目前的模型忽略了线粒体Ca2+的这种状态。
