Mitochondrial function in myasthenia gravis

We determined the respiration rate, respiratory control and ADP/O ratios, with different substrates in mitochondria isolated from 2 patients with myasthenia gravis and compared them with normal human muscle. In all cases studied, a severe alteration of the respiratory control with variable derangement of oxidative phosphorylation was found. This abnormality of mitochondrial metabolism was referred to by Luft as 'loosely coupled' and was reported in other neuromuscular diseases. In our opinion this defective oxidative metabolism is nonspecific.