Savage M K, Reed D J
Department of Biochemistry and Biophysics, Oregon State University, Corvallis 97331-7305.
Arch Biochem Biophys. 1994 Nov 15;315(1):142-52. doi: 10.1006/abbi.1994.1483.
Treatment of isolated mitochondria with calcium and inorganic phosphate induces inner membrane permeability that is thought to be mediated through a non-selective, calcium-dependent pore. The inner membrane permeability results in the rapid efflux of small matrix solutes such as glutathione and calcium, loss of coupled functions, and large amplitude swelling. We have identified conditions of permeability transition without large amplitude swelling, a parameter often used to assess inner membrane permeability. The addition of either oligomycin, antimycin, or sulfide to incubation buffer containing calcium and inorganic phosphate abolished large-amplitude swelling of mitochondria but did not prevent inner membrane permeability as demonstrated by the release of mitochondrial glutathione and calcium. The release of both glutathione and calcium was inhibited by the addition of cyclosporin A, a potent inhibitor of permeability transition. Transmission electron microscopy analysis, combined with the glutathione and calcium release data, indicate that permeability transition can be observed in the absence of large-amplitude swelling. Permeability transition occurring both with and without large-amplitude swelling was accompanied by a collapse of the membrane potential. We conclude that cyclosporin A-sensitive permeability transition can occur without obvious morphological changes such as large-amplitude swelling. Monitoring the cyclosporin A-sensitive release of concentrated endogenous matrix solutes, such as GSH, may be a sensitive and useful indicator of permeability transition.
用钙和无机磷酸盐处理分离的线粒体可诱导内膜通透性，这种通透性被认为是通过一种非选择性的、钙依赖性孔介导的。内膜通透性导致小的基质溶质如谷胱甘肽和钙的快速外流、偶联功能丧失以及大幅度肿胀。我们已经确定了通透性转换的条件，即没有大幅度肿胀，而大幅度肿胀是常用于评估内膜通透性的一个参数。在含有钙和无机磷酸盐的孵育缓冲液中添加寡霉素、抗霉素或硫化物可消除线粒体的大幅度肿胀，但并不阻止内膜通透性，线粒体谷胱甘肽和钙的释放证明了这一点。添加环孢素A（一种有效的通透性转换抑制剂）可抑制谷胱甘肽和钙的释放。透射电子显微镜分析结合谷胱甘肽和钙释放数据表明，在没有大幅度肿胀的情况下也可观察到通透性转换。有或没有大幅度肿胀时发生的通透性转换都伴随着膜电位的崩溃。我们得出结论，环孢素A敏感的通透性转换可以在没有明显形态变化如大幅度肿胀的情况下发生。监测浓缩的内源性基质溶质如谷胱甘肽的环孢素A敏感释放可能是通透性转换的一个敏感且有用的指标。
