Ultrastructure of extensor digitorum longus (EDL) muscle fibers of alloxan-diabetic rats

The diabetic effects of alloxan (type I diabetes mellitus) were investigated in 40 Wistar albino rats (18 controls and 22 diabetics). Alloxan in sterile physiological saline was injected into the animals intravenously. The ultrastructure of type IIa, type IIb and type I fibers in extensor digitorum longus (EDL) muscle of normal and alloxan diabetic rats was studied. In diabetic animals, the mitochondria of type IIa and type I fibers showed a loss of cristae. There was also an increased number of lipid droplets. The shape of the nuclei was highly irregular in these fibers. The type IIb fibers showed some disorientation of the T-tubuler system. It is concluded that alloxan-diabetes has differential effect on the fine structure of the three fiber types in rat skeletal muscle.