Related Experiment Video
Updated: Jul 18, 2026

Loading a Calcium Dye into Frog Nerve Endings Through the Nerve Stump: Calcium Transient Registration in the Frog Neuromuscular Junction
Published on: July 8, 2017
Augmentation of calcium influx by stannous chloride at mouse motor nerve terminals
1Department of Dental Pharmacology, Matsumoto Dental College, Shiojiri, Japan.
Abstract:
Stannous chloride (SnCl2) facilitates the calcium (Ca) entry into the frog motor nerve terminals. To compare the mode of action of SnCl2 on the Ca channels in the mouse with that in the frog, we investigated the effects of SnCl2 on the inward Ca current at the nerve terminals. SnCl2 (0.1 mM) did not change the second positive component of the action potential (an outward potassium (K) current) at the terminal part of the nerve terminal. SnCl2 (0.1 mM) increased the amplitude of the prolonged negative or positive deflection (an inward Ca current) evoked by treatment with 1 mM tetraethylammonium and 0.1 mM 3,4-diaminopyridine at the terminal or preterminal part of the nerve terminal, respectively. This augmenting effect of SnCl2 was inhibited by cumulative addition of Ca channel blockers, i.e., 0.1 mM CdCl2, 5 mM NiCl2, 5 mM CoCl2, 5 mM MnCl2, or 10 mM MgCl2. From the results obtained, it has been confirmed that SnCl2 facilitates the transmitter release by enhancing the Ca influx at the nerve terminals but not by blocking the K channels and that the mode of action of SnCl2 in the mouse is identical with that in the frog.
Related Concept Videos
Feedback Regulation of Calcium Concentration
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Ligand-Gated Ion Channel Receptor: Gating Mechanism
Neuromuscular Junction And Blockade
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.
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...

