Sarcomere length-dependent Ca2+ activation in skinned rabbit psoas muscle fibers: coordinated regulation of thin filament cooperative activation and passive force.

ABSTRACT: In skeletal muscle, active force production varies as a function of sarcomere length (SL). It has been considered that this SL dependence results simply from a change in the overlap length between the thick and thin filaments. The purpose of this study was to provide a systematic understanding of the SL-dependent increase in Ca(2+) sensitivity in skeletal muscle, by investigating how thin filament "on-off" switching and passive force are involved in the regulation. Rabbit psoas muscles were skinned, and active force measurements were taken at various Ca(2+) concentrations with single fibers, in the short (2.0 and 2.4 μm) and long (2.4 and 2.8 μm) SL ranges. Despite the same magnitude of SL elongation, the SL-dependent increase in Ca(2+) sensitivity was more pronounced in the long SL range.

SUBMITTER: Fukuda N 

PROVIDER: S-EPMC3204045 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature