Related Experiment Video
Updated: Aug 13, 2026

In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
Probing excitation-contraction coupling in trachealis smooth muscle with the mycotoxin cyclopiazonic acid
Abstract:
1. Muscarinic stimulation-induced tonic contraction of airway smooth muscle is independent of membrane potential. This contraction is not sensitive to inhibition by voltage-operated Ca2+ channel blockers or by K+ channel openers. 2. Cyclopiazonic acid (CPA) inhibits Ca2+ loading of internal stores but does not affect maximal tonic contraction induced by acetylcholine (ACh) in steady state conditions. 3. After depletion of internal Ca2+ stores with CPA, ACh-induced tonic contraction becomes dependent upon values of membrane potential. The contraction is then sensitive to voltage-operated Ca2+ channel blockers and to K+ channel openers. 4. Treatment of trachealis muscle with CPA potentiates the M2-mediated component of ACh stimulation, but this potentiation is not entirely responsible for the switch in excitation-contraction (E-C) coupling. 5. It is proposed that depletion of internal Ca2+ stores with CPA and promotion of M2-stimulation can lead to a switch in E-C coupling in trachealis smooth muscle from pharmaco- to electromechanical mode, perhaps by targeting a plasma membrane K+ channel.
More Related Videos
Related Concept Videos
Muscle Contraction
Muscle Contraction
Excitation-Contraction Coupling in Skeletal Muscles
When an action potential...
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...

