Altered tissue carnitine levels in animals with hereditary muscular dystrophy.

Low levels of muscle carnitine have been found in patients with Duchenne dystrophy, a case possibly of Becker dystrophy, and limb-girdle syndrome as well as in patients with the recently described muscle carnitine deficiency syndrome. Tissues of the mouse, hamster, and chicken were analyzed to determine whether tissue carnitine levels were altered in the animal models of muscular dystrophy. Significantly higher levels of carnitine were found in dystrophic mouse muscle, but carnitine levels in plasma, liver and heart were normal. Histological changes in the skeletal muscle of dystrophic hamsters were relatively mild, and both skeletal muscle and plasma levels were normal. The liver carnitine level was higher than normal levels. The dystrophic hamster also had an inherited cardiomyopathy, and interestingly its heart carnitine level was much lower than normal. The red muscle of the normal chicken contained 5 times the level of carnitine found in white muscle. The dystrophic chicken had higher than normal levels of carnitine in the white muscle, but normal levels in the red muscle. Although all 3 animal models of muscular dystrophy studied have altered levels of carnitine in some tissue, none of the animal models had the same pattern of altered tissue carnitine levels seen in human patients.