Effect of denervation on regenerating muscle plasma membrane integrity: freeze-fracture and dystrophin immunostaining analyses

Summary We investigated time sequentially, the densities of intramembranous assembly orthogonal arrays of regenerating rat extensor digitorum longus muscle after bupivacaine-induced muscle injury. There was no evidence of orthogonal arrays at the early stage, but the densities of orthogonal arrays increased with the maturation of the innervated regenerating myofibers. In contrast, the orthogonal arrays were scarcely observed at any time point examined in denervated regenerating muscles. Therefore, the neural factor may have an important effect on the appearance of orthogonal arrays. Moreover, we studied the immunostainability of Duchenne muscular dystrophy gene product dystrophin in the regenerating muscle at the same time points. Positive immunostaining was observed in both innervated and denervated regenerating myofibers even from the early stage of regeneration. On the basis of these data, the relationship between orthogonal array and dystrophin are discussed.Supported in part by grants from the Ministry of Education and from the National Center for Nervous, Mental and Muscular Disorders of the Ministry of Health and Welfare (62A-2-20), Japan