Related Experiment Video
Updated: Aug 13, 2026

Physiological Recordings of High and Low Output NMJs on the Crayfish Leg Extensor Muscle
Published on: November 17, 2010
Charge movements near the mechanical threshold in skeletal muscle of Rana temporaria
Abstract:
Charge movement was investigated over a range of potentials close to the mechanical threshold in voltage-clamped frog skeletal muscle. The delayed (q gamma) component of the charging currents appeared with a time course lasting well over 100 ms at around -50 to -40 mV, but the currents became larger and faster with further depolarization. The slow charging current was investigated using a 10 mV probe step intercepting the time course of these currents. This procedure showed that the charging currents could last as long as 100-300 ms. The total charge was conserved when the charging current was small and prolonged. The results can be related directly to earlier findings concerning contractile activation of muscle by applied voltage steps to potentials near threshold ( Adrian , Chandler & Hodgkin, 1969).
Related Concept Videos
Generation of Action Potential in Skeletal Muscles
Like neurons, muscle cells are also regarded as excitable due to their capacity to change in response to stimuli, primarily due to voltage-gated ion channels embedded in their plasma membranes, which get activated by alterations in the cell's...
Excitation-Contraction Coupling in Skeletal Muscles
When an action potential...
Relaxation of Skeletal Muscles
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
Motor Unit Stimulation
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
Muscle Stimulation Frequency
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Design Example: Frog Muscle Response
When the switch connecting the RL circuit is closed, a brief muscle contraction is observed. This is because, at a steady state, the inductor acts like a short circuit,...

