Ethanol-induced chronic myopathy in the young rat: a light and electron microscopic study in type I or type II fibre-rich skeletal muscles.

An investigation was made into the characteristics of an experimental chronic alcoholic myopathy in the young rat. Male Wistar rats were fed a diet for 6 weeks in which ethanol comprised 36% of total energy. Controls were pair-fed the same diet except ethanol was substituted by isoenergic glucose. Soleus (type I fibre-rich) and plantaris (type II fibre-rich) muscles were examined by light microscopy, histochemistry and electron microscopy. Muscles from ethanol-fed rats showed a low-grade myopathy and the diameters of individual type II fibres were reduced. Infrequent atrophic fibres were necrotic and undergoing phagocytosis. Ultrastructurally, there were no observable differences in the subcellular organelles of the alcohol-fed and control rats. It was concluded that alcohol causes a specific myopathic process in the rat, selectively affecting type II fibres. These changes correlate well with the abnormalities seen in human chronic alcoholic myopathy.