Effects on skeletal muscle fibres of diabetes and Ginkgo biloba extract treatment

Combined cytophotometric and morphometric analysis of muscle fibre properti es and myosin heavy chain electrophoresis were performed on extensor digito rum longus and soleus muscles from healthy rats and rats with streptozotoci n-induced diabetes. Moreover, the protective effect of Ginkgo biloba extrac t, a potent oxygen radical scavenger, on diabetic muscles was investigated. Changes in fibre type-related enzyme activities, fibre type distribution, fibre cross areas and myosin isoforms were found. In muscles of diabetic ra ts, a metabolic shift was measured mainly in fibres with oxidative metaboli sm. Fast-oxidative glycolytic fibres showed a shift to more glycolytic meta bolism and about a third transformed into fast-glycolytic fibres. Slow-oxid ative fibres became more oxidative. Fibre atrophy was measured in diabetic muscles dependent on fibre type and muscle. Different fibre types atrophied to a different degree. Therefore, a decreased area percentage of slow fibr es and an increased area percentage of fast fibres of the whole muscle cros s section in both muscles were found. This is supported by reduced slow and increased fast myosin heavy chain isoforms. These alterations of diabetic muscle fibres could be due to less motion of diabetic rats and diabetic neu ropathy. After treatment with Ginkgo biloba extract, enzyme activities were increased mainly in oxidative fibres of diabetic muscles, which was interp reted as protective effect. Generally, the soleus muscle with predominant o xidative metabolism was more vulnerable to diabetic alterations and Ginkgo biloba extract treatment than the extensor digitorum longus muscle with pre dominant glycolytic metabolism.