Objective: To analyze the levels of free carnitine and carnitine esters in the muscles of patients with inflammatory myopathies.
Methods: Six men and 7 women with inflammatory myopathy and 25 age-matched healthy controls were studied. Free carnitine and carnitine esters in muscle homogenates were measured by a radiochemical procedure. Muscle histochemical staining and measurement of respiratory chain enzyme activity were also performed.
Results: Eleven patients had muscle carnitine insufficiency. Five of them had subsarcolemmal oxidative accumulations, 5 had lipid droplets, and 4 had defects of the respiratory chain enzyme complexes.
Conclusion: Abnormal distribution of muscle carnitine is present in patients with inflammatory myopathies and could impair muscle function. Coexistent mitochondrial dysfunction may contribute to carnitine insufficiency.