Dubinin M V, Vedernikov A A, Khoroshavina E I, Samartsev V N
Mari State University, Yoshkar-Ola, 424001, Russia.
Biochemistry (Mosc). 2014 Jun;79(6):571-6. doi: 10.1134/S000629791406011X.
In liver mitochondria loaded with Ca2+ or Sr(2+), α,ω-hexadecanedioic acid (HDA) can induce nonspecific permeability of the inner membrane (mitochondrial pore) by the mechanism insensitive to cyclosporin A (CsA). In this work we studied the effect of ionic strength of the incubation medium on the kinetics of the processes that accompany Ca2+-dependent induction of the mitochondrial pore by fatty acid: organelle swelling, Ca2+ release from the matrix, changes in transmembrane potential (Δψ) and rate of oxygen consumption, and the release of cytochrome c from the intermembrane space. Two basic incubation media were used: sucrose medium and isotonic ionic medium containing KCl without sucrose. We found that 200 μM Ca2+ and 20 μM HDA in the presence of CsA effectively induce high-amplitude swelling of mitochondria both in the case of sucrose and in the ionic incubation medium. In the presence of CsA, mitochondria can rapidly absorb Ca2+ and retain it in the matrix for a while without reducing Δψ. Upon incubation in the ionic medium, mitochondria retain most of the added Ca2+ in the matrix for a short time without reducing the Δψ. In both cases the addition of HDA to the mitochondria 2 min after the introduction of Ca2+ leads to the rapid release of these ions from the matrix and total drop in Δψ. The mitochondrial swelling induced by Ca2+ and HDA in non-ionic medium is accompanied by almost maximal stimulation of respiration. Under the same conditions, but during incubation of mitochondria in the ionic medium, it is necessary to add cytochrome c for significant stimulation of respiration. The mitochondrial swelling induced by Ca2+ and HDA leads to the release of cytochrome c in a larger amount in the case of ionic medium than for the sucrose medium. We conclude that high ionic strength of the incubation medium determines the massive release of cytochrome c from mitochondria and liberates it from the respiratory chain, which leads to blockade of electron transport along the respiratory chain and consequently to disruption of the energy functions of the organelles.
在加载了Ca2+或Sr2+的肝线粒体中，α,ω-十六烷二酸（HDA）可通过对环孢菌素A（CsA）不敏感的机制诱导内膜（线粒体孔）的非特异性通透性。在这项工作中，我们研究了孵育介质的离子强度对脂肪酸依赖Ca2+诱导线粒体孔过程动力学的影响：细胞器肿胀、Ca2+从基质释放、跨膜电位（Δψ）变化、氧气消耗速率以及细胞色素c从膜间隙释放。使用了两种基本的孵育介质：蔗糖介质和不含蔗糖但含KCl的等渗离子介质。我们发现，在CsA存在的情况下，200μM Ca2+和20μM HDA在蔗糖介质和离子孵育介质中均能有效诱导线粒体的高幅度肿胀。在CsA存在的情况下，线粒体可迅速吸收Ca2+并将其在基质中保留一段时间而不降低Δψ。在离子介质中孵育时，线粒体在短时间内将大部分添加的Ca2+保留在基质中而不降低Δψ。在这两种情况下，在引入Ca2+后2分钟向线粒体中添加HDA会导致这些离子从基质中迅速释放以及Δψ完全下降。在非离子介质中由Ca2+和HDA诱导的线粒体肿胀几乎伴随着呼吸的最大刺激。在相同条件下，但在线粒体在离子介质中孵育时，需要添加细胞色素c才能显著刺激呼吸。在离子介质中，由Ca2+和HDA诱导的线粒体肿胀导致细胞色素c的释放量比在蔗糖介质中更大。我们得出结论，孵育介质的高离子强度决定了细胞色素c从线粒体的大量释放，并使其从呼吸链中释放出来，这导致呼吸链上电子传递的阻断，从而破坏细胞器的能量功能。
