Canton M, Luvisetto S, Schmehl I, Azzone G F
C.N.R. Unit for the Study of Physiology of Mitochondria, University of Padova, Italy.
Biochem J. 1995 Sep 1;310 ( Pt 2)(Pt 2):477-81. doi: 10.1042/bj3100477.
A new criterion is utilized for the interpretation of flow-force relationships in rat liver mitochondria. The criterion is based on the view that the nature of the relationship between the H+/O ratio and the membrane potential can be inferred from the relationship between ohmic-uncoupler-induced extra respiration and the membrane potential. Thus a linear relationship between extra respiration and membrane potential indicates unequivocally the independence of the H+/O ratio from the membrane potential and the leak nature of the resting respiration [Brand, Chien, and Diolez (1994) Biochem. J. 297, 27-29]. On the other hand, a non-linear relationship indicates that the H+/O ratio is dependent on the membrane potential. The experimental assessment of this relationship in the presence of an additional ohmic leak, however, is rendered difficult by both the uncoupler-induced depression of membrane potential and the limited range of dependence of the H+/O ratio on the membrane potential. We have selected conditions, i.e. incubation of mitochondria at low temperatures, where the extent of non-linearity is markedly increased. It appears that the nature of the resting respiration of mitochondria in vitro is markedly dependent on the temperature: at low temperatures the percentage of resting respiration due to membrane leak decreases and that due to intrinsic uncoupling of the proton pumps increases.
一种新的标准被用于解释大鼠肝线粒体中的流量-力关系。该标准基于这样一种观点，即H⁺/O比率与膜电位之间关系的性质可以从欧姆解偶联剂诱导的额外呼吸与膜电位之间的关系推断出来。因此，额外呼吸与膜电位之间的线性关系明确表明H⁺/O比率与膜电位无关以及静息呼吸的泄漏性质[布兰德、钱和迪奥莱兹（1994年）《生物化学杂志》297卷，27 - 29页]。另一方面，非线性关系表明H⁺/O比率依赖于膜电位。然而，在存在额外欧姆泄漏的情况下，由于解偶联剂引起的膜电位降低以及H⁺/O比率对膜电位的依赖范围有限，对这种关系进行实验评估变得困难。我们选择了一些条件，即线粒体在低温下孵育，此时非线性程度会显著增加。体外线粒体静息呼吸的性质似乎明显依赖于温度：在低温下，由于膜泄漏导致的静息呼吸百分比降低，而由于质子泵固有解偶联导致的静息呼吸百分比增加。
