What question did this study set out to answer?

The study aims to understand the contractile mechanism and force response of frog muscle fibers during varying lengths of steady extension.

December 1, 1990The Journal of PhysiologyOpen Access

The contractile response during steady lengthening of stimulated frog muscle fibres.

Q: What is the clinical evidence from this study?

Population: Isolated frog muscle fibres. Intervention: Steady lengthenings at different velocities vs. Isometric tetanus plateau / different speeds. Primary outcome: Force response / tension.

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Key result

Steady lengthening of a tetanized frog muscle fibre induces a cross-bridge cycle characterized by fast detachment of the cross-bridge extended beyond a critical level, with tension reaching 1.9-2 times isometric tetanic force.

Key Points

The study aims to understand the contractile mechanism and force response of frog muscle fibers during varying lengths of steady extension.
Isolated frog muscle fibers were stimulated and lengthened using a motor at controlled velocities (0.025-1.2 microns/s).
Force response was measured with a capacitance gauge transducer; length was tracked using a striation follower.
Non-homogeneous preparations during lengthening were excluded from analysis.
Steady tension reached after approximately 20 nm of lengthening, increasing up to 1.9-2 times the isometric tetanic force at speeds of 0.25-0.4 micron/s.
Transient tension peaks occurred before steady levels were established, influenced by the speed of lengthening, reaching a peak tension at 10-14 nm extension.
Instantaneous stiffness during steady lengthening was found to be 10-20% larger than at isometric tetanus, remaining constant across tested velocities.

Structured PICO

Population

Isolated frog muscle fibres

Intervention

Steady lengthening at different velocities (0.025-1.2 microns/s per half-sarcomere; temperature 2-5.5 degrees C) imposed at the isometric tetanus plateau

Comparator

Isometric tetanus plateau (baseline) and varying speeds of lengthening

Outcome

Force response (tension) and instantaneous stiffnesssurrogate

Steady lengthening of a tetanized frog muscle fibre induces a cross-bridge cycle characterized by fast detachment of the cross-bridge extended beyond a critical level.

Discussion

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Implication

May refine models of eccentric force production; leaves open translation to mammalian or cardiac muscle.

Cite This Study

Lombardi et al. (1990) studied Isolated frog muscle fibres. Steady lengthenings at different velocities vs. Isometric tetanus plateau / different speeds was evaluated on Force response / tension. Steady lengthening of a tetanized frog muscle fibre induces a cross-bridge cycle characterized by fast detachment of the cross-bridge extended beyond a critical level, with tension reaching 1.9-2 times isometric tetanic force.

synapsesocial.com/papers/6a16d83ff3be5e880d6b9e09 https://doi.org/10.1113/jphysiol.1990.sp018324

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The contractile response during steady lengthening of stimulated frog muscle fibres.

Key Points

Structured PICO

Discussion

Implication

Cite This Study

The contractile response during steady lengthening of stimulated frog muscle fibres.

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Also Consider