Asami K, Irimajiri A
Biochim Biophys Acta. 1984 Dec 19;778(3):570-8. doi: 10.1016/0005-2736(84)90408-5.
The dielectric dispersion of isolated intact mitochondria in suspension has been measured between 10 kHz and 500 MHz. In isotonic KCl media at 4 degrees C, the mitochondria maintained their characteristic 'double membrane' structure as examined by electron microscopy, and the observed dispersion curves were successfully simulated in terms of a superposition of two sub-dispersions having different characteristic frequencies and different permittivity magnitudes. Taking these observations into account we analyzed the dispersion data on the basis of a 'double-shell' model in which two concentric shells are meant to represent the mitochondrial outer and inner membranes. The analyses by a computerized curve-fitting method revealed that: (i) electric capacities for the outer and the inner membrane are 1.7 and 0.5 microF/cm2, respectively, (ii) relative permittivity for the inner compartment (or the equivalent homogeneous matrical space) = 50-60, (iii) outer compartment-to-external conductivity ratio = 0.4-0.6, and (iv) inner compartment-to-external conductivity ratio = 0.14. The implications of these parameter values are discussed with due attention paid to the limitations inherent in our 'double-shell' model approach.
已测量了悬浮状态下分离的完整线粒体在10千赫兹至500兆赫兹之间的介电色散。在4摄氏度的等渗氯化钾介质中，通过电子显微镜检查发现线粒体保持其特征性的“双膜”结构，并且观察到的色散曲线通过叠加具有不同特征频率和不同介电常数大小的两个子色散成功地进行了模拟。考虑到这些观察结果，我们基于“双壳”模型分析了色散数据，其中两个同心壳旨在代表线粒体外膜和内膜。通过计算机化曲线拟合方法分析表明：（i）外膜和内膜的电容分别为1.7和0.5微法/平方厘米，（ii）内部隔室（或等效均匀基质空间）的相对介电常数=50-60，（iii）外隔室与外部电导率之比=0.4-0.6，以及（iv）内隔室与外部电导率之比=0.14。我们在充分注意到“双壳”模型方法固有局限性的情况下，讨论了这些参数值的含义。
