Phosphorus-31 magnetic resonance spectroscopy of skeletal muscle in maternally inherited diabetes and deafness A3243G mitochondrial mutation carriers.

PURPOSE: To investigate high-energy phosphate metabolism in striated skeletal muscle of patients with Maternally Inherited Diabetes and Deafness (MIDD) syndrome.

MATERIALS AND METHODS: In 11 patients with the MIDD mutation (six with diabetes mellitus [DM] and five non-DM) and eight healthy subjects, phosphocreatine (PCr) and inorganic phosphate (Pi) in the vastus medialis muscle was measured immediately after exercise using (31)P-magnetic resonance spectroscopy (MRS). The half-time of recovery (t1/2) of monoexponentially fitted (PCr+Pi)/PCr was calculated from spectra obtained every 4 seconds after cessation of exercise. A multiple linear regression model was used for statistical analysis.

RESULTS: Patients with the MIDD mutation showed a significantly prolonged t1/2 (PCr+Pi)/PCr after exercise as compared to controls (13.6+/-3.0 vs. 8.7+/-1.3 sec, P = 0.01). No association between the presence of DM and t1/2 (PCr + Pi)/PCr was found (P = 0.382).

CONCLUSION: MIDD patients showed impaired mitochondrial oxidative phosphorylation in skeletal muscle shortly after exercise, irrespective of the presence of DM.