Kemp G J, Taylor D J, Radda G K
MRC Biochemical and Clinical Magnetic Resonance Unit, John Radcliffe Hospital, Oxford, UK.
NMR Biomed. 1993 Jan-Feb;6(1):66-72. doi: 10.1002/nbm.1940060111.
Information about the control of mitochondrial function in skeletal muscle in vivo can be obtained from the relationship between the rate of mitochondrial oxidation and the intracellular concentrations of phosphorus metabolites, although the analysis is complicated by the constraints imposed by the creatine kinase equilibrium. The rate of phosphocreatine (PCr) recovery after exercise measured by 31P MRS is an estimate of net oxidative ATP synthesis. Analysing such data from normal and abnormal human muscle, we show that the approximately exponential recovery kinetics of ADP and PCr imply that the rate of PCr resynthesis has a hyperbolic dependence on [ADP] but remains approximately linear with respect to the concentration of orthophosphate (Pi) and therefore also [PCr] and [creatine]. Both kinds of relationship are consistent with experimental data from exercising animal muscle and also with data from isolated mitochondria which suggest kinetic control of mitochondrial ATP synthesis of [ADP]. These relationships are altered in proven mitochondrial disease. This analysis offers a way to quantify mitochondrial function and its abnormalities in vivo.
尽管肌酸激酶平衡所带来的限制使分析变得复杂，但通过线粒体氧化速率与磷代谢产物细胞内浓度之间的关系，可以获得有关体内骨骼肌线粒体功能控制的信息。通过31P MRS测量运动后磷酸肌酸（PCr）的恢复速率是对净氧化ATP合成的一种估计。分析来自正常和异常人类肌肉的此类数据，我们发现ADP和PCr近似指数恢复动力学意味着PCr再合成速率对[ADP]呈双曲线依赖性，但相对于正磷酸盐（Pi）的浓度以及因此的[PCr]和[肌酸]浓度仍近似呈线性。这两种关系都与运动动物肌肉的实验数据一致，也与来自分离线粒体的数据一致，这些数据表明线粒体ATP合成受[ADP]的动力学控制。在已证实的线粒体疾病中，这些关系会发生改变。该分析提供了一种在体内量化线粒体功能及其异常的方法。
