Barnes P R, Kemp G J, Taylor D J, Radda G K
MRC Biochemical and Clinical Magnetic Resonance Unit, Oxford Radcliffe Hospital, UK.
Brain. 1997 Oct;120 ( Pt 10):1699-711. doi: 10.1093/brain/120.10.1699.
We have used 31P magnetic resonance spectroscopy to investigate skeletal muscle bioenergetics in a total of 31 patients with myotonic dystrophy. Results from resting flexor digitorum superficialis and calf muscle showed a significant elevation in the concentration ratio of inorganic phosphate to ATP and a significant reduction in the phosphorylation potential. In addition, in resting calf muscle the concentration ratio of phosphocreatine to ATP was reduced, and the resting intracellular pH and calculated free cytosolic ADP concentration were elevated. In general, the abnormalities observed were more marked in those patients who were more severely affected as judged by their ability to exercise. During aerobic exercise in both calf muscle and flexor digitorum superficialis, phosphocreatine was depleted more rapidly in patients than in control subjects but the muscle acidified less and ADP concentrations were higher. Calculated ATP turnover was significantly elevated. Analysis of the recovery kinetics for phosphocreatine following exercise provides evidence for a small but significant reduction in mitochondrial function. Analysis of the response of flexor digitorum superficialis to ischaemic exercise provides evidence of a reduction in the relative utilization of glycogen to produce ATP which may account, in part, for the reduced acidification seen in exercising muscle in myotonic dystrophy. There was no definite evidence of an alteration in proton handling capacity in this condition.
我们运用31P磁共振波谱法，对总共31例强直性肌营养不良患者的骨骼肌生物能量学进行了研究。来自静息状态下的指浅屈肌和小腿肌肉的结果显示，无机磷酸与ATP的浓度比显著升高，磷酸化电位显著降低。此外，静息状态下小腿肌肉中磷酸肌酸与ATP的浓度比降低，静息细胞内pH值和计算得出的游离胞质ADP浓度升高。总体而言，根据患者的运动能力判断，病情越严重的患者所观察到的异常越明显。在小腿肌肉和指浅屈肌进行有氧运动时，患者的磷酸肌酸消耗速度比对照组更快，但肌肉酸化程度更低，ADP浓度更高。计算得出的ATP周转率显著升高。对运动后磷酸肌酸恢复动力学的分析表明，线粒体功能有轻微但显著的降低。对指浅屈肌对缺血性运动的反应分析表明，糖原产生ATP的相对利用率降低，这可能部分解释了强直性肌营养不良患者运动肌肉中酸化程度降低的原因。在这种情况下，没有明确证据表明质子处理能力发生改变。
