What question did this study set out to answer?

To determine the relationship between thin filament activation, isometric force, and the rate of force generation independently of calcium concentration.

January 1, 2001Journal of Biological ChemistryOpen Access

Modulation of Contractile Activation in Skeletal Muscle by a Calcium-insensitive Troponin C Mutant

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To determine the relationship between thin filament activation, isometric force, and the rate of force generation independently of calcium concentration.
Extracted native skeletal troponin C from isolated skeletal muscle fibers.
Replaced native troponin C with controlled mixtures of functional cardiac troponin C and a permanently inactive, calcium-insensitive mutant.
Measured isometric force and the kinetics of force development across varying levels of thin filament activation at saturating calcium concentrations.
Isometric force displayed a direct, linear relationship with the number of cross-bridges binding to the thin filament.
Above 35% maximal isometric activation at saturating calcium levels, the rate of force generation was independent of the density of available actin sites.
Force reduction via lower calcium concentrations markedly slowed the rate of force generation, contrasting with the rate independence observed when reducing force via mutant troponin substitution.

Structured PICO

Population

Skeletal muscle fibers

Intervention

Extraction of skeletal troponin C and replacement with mixtures of functional cardiac and mutant cardiac troponin C insensitive to calcium

Comparator

Varying calcium concentrations

Outcome

Relationship between the extent of thin filament activation (fractional calcium binding), isometric force, and the rate of force generationsurrogate

The findings support the hypothesis that calcium controls the transition between weakly and strongly bound cross-bridge states in skeletal muscle.

Discussion

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Implication

No immediate clinical implications; leaves open whether calcium-dependent cross-bridge kinetics translate to cardiac muscle or in vivo settings.

Cite This Study

Morris et al. (2001) studied this question.

synapsesocial.com/papers/6a70d1e8e5469ee92be17e5a https://doi.org/10.1074/jbc.m007371200

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Implication

No immediate clinical implications; leaves open whether calcium-dependent cross-bridge kinetics translate to cardiac muscle or in vivo settings.

Modulation of Contractile Activation in Skeletal Muscle by a Calcium-insensitive Troponin C Mutant

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Modulation of Contractile Activation in Skeletal Muscle by a Calcium-insensitive Troponin C Mutant

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Also Consider