Pattern Dependence in the Stimulation‐Induced Type Transformation of Rabbit Fast Skeletal Muscle

E-ISSN： 1525-1403|6|3|176-189

ISSN： 1094-7159

Source： NEUROMODULATION: TECHNOLOGY AT THE NEURAL INTERFACE, Vol.6, Iss.3, 2003-07, pp. : 176-189

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

A<sc>bstract</sc>Little is known of the events that initiate the adaptive response of skeletal muscle to a sustained change in use. This study was designed to distinguish between the role of the electrical activity pattern and that of the resulting contractile force in driving different aspects of the response. A better understanding of these issues would lead to improved clinical protocols for functional electrical stimulation. Rabbit limb muscles were stimulated continuously for 12 weeks either at 2.5 Hz or with an equivalent optimized pattern producing peak forces three‐fold higher. The two patterns induced similar changes in shortening velocity, myosin isoforms, and fatigue resistance. They had markedly different effects on twitch dynamics and summation (“doublet effect”). This pointed to differences in activation that were not, however, attributable to sarcoplasmic reticulum Ca²⁺ transport ATPase activity. The optimized pattern maintained muscle bulk more effectively. We conclude that changes in myosin isoform composition and fatigue resistance are driven by aggregate impulse activity. Changes in Ca²⁺ transport and muscle bulk show a distinct pattern dependence.