Related Experiment Video
Updated: Aug 14, 2026
07:32
Analysis of Cardiac Contractile Dysfunction and Ca2+ Transients in Rodent Myocytes
Published on: May 25, 2022
Intracellular Ca2+ regulation in rat motoneurons during development
Govindan Dayanithi1, Ilana Mechaly, Cédric Viero
1INSERM-U 583, Institut des Neurosciences de Montpellier, Hôpital St. Eloi, BP 74103, 80 Rue Augustin FLICHE-34091, Montpellier Cedex 5, France. gdaya@univ-montp2.fr
Cell Calcium
|December 6, 2005
Summary
Intracellular calcium ([Ca(2+)](i)) regulation in developing rat motoneurons is controlled by endoplasmic reticulum stores. Ryanodine-sensitive channels, linked to L-type calcium channels, play a key role in calcium homeostasis during neurogenesis.
Area of Science:
- Neuroscience
- Cellular Biology
- Developmental Biology
Background:
- Intracellular calcium concentration ([Ca(2+)](i)) is crucial for neuromuscular synapse formation.
- Endoplasmic reticulum (ER) Ca(2+) stores, modulated by ryanodine (RYR) and inositol trisphosphate (IP(3)) receptors, influence neuronal [Ca(2+)](i) homeostasis.
- Understanding the developmental regulation of these Ca(2+) signaling pathways in motoneurons is essential.
Purpose of the Study:
- To investigate the molecular mechanisms of ER Ca(2+) store involvement in [Ca(2+)](i) homeostasis during embryonic rat motoneuron development.
- To explore the roles of RYR and IP(3)-sensitive Ca(2+) channels in regulating [Ca(2+)](i) in developing motoneurons.
Main Methods:
- Fura-2 microspectrofluorimetry was used to monitor [Ca(2+)](i) in single embryonic rat motoneurons cultured in vitro.
- Pharmacological agents (caffeine, ryanodine, nicardipine, omega-conotoxins, thapsigargin, CPA, Xestospongin-C) were employed to probe Ca(2+) channel function.
- RT-PCR was utilized to analyze the expression patterns of RYR and IP(3) Ca(2+) channel isoforms.
Main Results:
- Caffeine-induced [Ca(2+)](i) responses increased progressively in motoneurons from days 1-7 in culture, suggesting developmental changes in ER Ca(2+) release.
- Ryanodine and nicardipine blocked caffeine-induced responses, indicating a functional link between RYR and L-type Ca(v)1 channels.
- Thapsigargin/CPA-induced [Ca(2+)](i) increases, reflecting ER store depletion, were prominent in early cultures but declined significantly by day 5-6.
- Xestospongin-C inhibited CPA-induced responses, confirming the role of IP(3) receptors.
- RT-PCR confirmed the expression of various RYR and IP(3) channel isoforms, with developmental changes noted for RYR channels.
Conclusions:
- Motoneuronal [Ca(2+)](i) homeostasis is developmentally regulated during the first week in vitro.
- A functional ryanodine-sensitive Ca(2+) channel mediates Ca(2+)-induced Ca(2+) release in embryonic motoneurons.
- This intracellular Ca(2+) release is coupled to voltage-dependent Ca(2+) entry via L-type Ca(2+) channels.
Related Concept Videos
01:27Feedback Regulation of Calcium Concentration
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:25Smooth Muscle Contraction
Smooth muscle contraction is a complex process vital for various bodily functions, from maintaining blood vessel tension to facilitating the movement of food through the digestive tract. Unlike striated muscles, smooth muscle contraction begins more slowly and lasts longer.
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...
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...
01:29Relaxation of Skeletal Muscles
The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
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.
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.