Related Experiment Video
Updated: Jun 20, 2026

Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice
Published on: September 17, 2015
[The significance of extracellular Ca2+ in contractile responses in chick amnion]
Abstract:
Neurotransmitter receptors are formed during chick embryo development in the amnion, an avascular extraembryonic membrane devoid of innervation. Carbachol induces phasic and tonic contractions mediated by M3 cholinoceptors in an amniotic membrane strip isolated from 11-14-day-old chick embryo. The carbachol effect on the amnion contractile activity was studied in normal physiological salt solution, during depolarization by K+, exposure to nifedipine, and in calcium-free medium. Voltage-dependent and receptor-operated Ca2+ channels as well as calcium from intracellular stores are involved in the contractile response to carbachol. Phasic contractions of the amnion are mainly induced by calcium ions entering through voltage-dependent calcium channels, while tonic contractions are also maintained by receptor-operated channels. Ca(2+)-activated potassium channels can serve as a negative feedback factor in regulation of the amnion contractile responses.
Related Concept Videos
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...
Cell-matrix's Response to Mechanical Forces
Anchoring junctions mechanically attach a cell to the...
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,...
Tension Response at Adherens Junctions
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin homology) domains...
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.
Intracellular Signaling Affects Focal Adhesions
Some...

