Key Points
- To determine whether the enhancement of skeletal muscle contraction by potentiating agents depends on muscle cell length and to evaluate physiological mechanisms governing this response.
- Examined contractile potentiation in vertebrate skeletal muscle cells across varying initial muscle and sarcomere lengths in the presence of potentiating agents.
- Assessed the relative contributions of intracellular calcium ion transients, temperature, chemical composition of potentiators, and the twitch-to-tetanic force ratio.
- The capacity of potentiating agents to amplify contractile force showed direct dependence on the initial length of the muscle cell.
- Intracellular calcium transients, temperature, agent chemistry, and twitch-to-tetanic force ratios influenced potentiation magnitude but failed to account for length dependence.
- Muscle cells operated below full activation during ordinary contractions across both shortened states and optimal sarcomere lengths.
Structured PICO
PPopulationvertebrae skeletal muscle cells
IInterventionpotentiating agents
OOutcomecontractile potentiation
Contractile potentiation in skeletal muscle depends on the initial length of the muscle cell, suggesting parts of the cell are normally less than fully active during contractions.