Histochemical study of the extensor digitorum longus and soleus muscles inalcoholic rats

The extensor digitorum longus (EDL) and soleus (SOL) muscle fibres from alb ino rats submitted to experimental chronic alcoholism were evaluated in acc ordance with their metabolic and morphometric profiles. Twenty-seven male a nimals aged 4 months and weighing approximately 400 g were used. The animal s were divided into three groups: control, isocaloric and alcoholic and sac rifices were carried out after 5, 10 and 15 months. The muscles were dissec ted, removed, cross-sectioned in a cryostat and submitted to the NADH (nico tinamide adenine dinucleotide) reaction. The SO (slow-twitch-oxidative), FG (fast-twitch-glycolytic) and FOG (fast-twitch-oxidative-glycolytic) muscle fibre types exhibited a polygonal, triangular or rounded shape and did not present noteworthy modifications in either muscles during the study. The c ross-sectional areas of the fibres from the studied muscles did not present significant differences during the observations. Fibre area behaved simila rly in the alcoholic animals up to the 10th month, i.e. it was decreased, a s also observed in the other groups. At 15 months, however, all fibres were increased, with a predominance of FG fibres in the SOL muscle. Changes in fibre population were observed mainly in the SOL muscle of alcoholic animal s: SO fibres were initially increased in number but decreased after the 10t h month, and the opposite was observed for the population of FG fibres. FOG fibres increased linearly in number throughout the experiment. The statist ical analysis showed nevertheless that the fibre population and cross-secti onal area changes were not significant. In the alcoholic animals quantitati ve variations of muscle fibres were more evident in the SOL muscle, suggest ing that the SOL muscle is more sensitive to the toxic action of ethanol. T he results concerning the increased fibre diameter in alcoholic animals wou ld be associated with muscle oedema induced directly or indirectly by the e thanol.