Alterations in Phenotype Expression of Muscle by Chronic Nerve Stimulation

Abstract

The experimentally induced transformation of adult mammalian fast-twitch muscle by chronic nerve stimulation has been established during the past years in our laboratory as a model for studying neural regulation of phenotypic gene expression in skeletal muscle. As was originally shown by Salmons and Vrbová (404), fast-twitch muscles of the rabbit are transformed into slow-twitch muscles by chronic indirect stimulation with a frequency pattern naturally occurring in nerves to slow-twitch muscles. This transformation affects the muscle fiber as a whole and concerns every functional, morphological and molecular property studied so far. The stimulation-induced transformation process has been investigated thoroughly in tibialis anterior (TA) and extensor digitorum longus (EDL) muscles of the rabbit with regard to the three main functional systems of the muscle fiber, i.e. energy metabolism, sarcoplasmic reticulum and proteins of the myofibrillar apparatus.