Abstract #1683

Qi J, Olsen N, Niermann K, Park J

Polymyositis (PM) is an inflammatory disease characterized by severe proximal weakness, inflammation and/or fat infiltration in the muscles, and elevated serum levels of muscle enzymes. ATP and PCr levels in quadriceps muscles showed 43% and 38% decreases during rest, exercise and recovery as compared to normal controls. Moreover, PM muscles showed increased Pi/PCr ratios and ADP levels, as well as decreased phosphorylation potentials. These data indicated defects in mitochondrial oxidative phosphorylation and are consistent with clinical fatigue and reduced work capacity. MRI and P-31MRS were instrumental in the elucidation of the pathophysiological mechanisms for PM disease progression.