Related Experiment Video
Updated: Aug 8, 2026

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
Published on: July 3, 2013
Dual effects of fluoride on the action potential, contraction, and membrane currents in frog atrial muscle
Abstract:
The effects of NaF (10(-7) - 10(-2) M) on the membrane potential, current, and contractile tension in bullfrog atrial muscle were investigated under voltage-clamped or unclamped conditions. NaF showed two opposite actions, positive and negative inotropic effects, depending on the concentration of the drug. NaF in lower concentrations produced a marked increase in contractility, a moderate prolongation of action potential, an augmentation of calcium response, and an increase of ICa-dependent tension. Contrarily, NaF in higher concentrations produced an inhibition of contractile tension associated with a shortening of action potential, an increase in potassium conductance, and an inhibition of calcium response. These results indicate that NaF affects the contractile response by dual mechanisms.
More Related Videos
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...
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...
Smooth Muscle Contraction
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
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,...
Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials

