Related Experiment Video
Updated: Jun 25, 2025
08:29
Assessment of Myofilament Ca2+ Sensitivity Underlying Cardiac Excitation-contraction Coupling
Published on: August 1, 2016
9.5K
Observation of sarcomere chaos induced by changes in calcium concentration in cardiomyocytes
Seine A Shintani1,2,3
1Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai, Aichi 487-8501, Japan.
Biophysics and Physicobiology
|May 28, 2024
Summary
Calcium fluctuations induce chaotic instability in sarcomeres during hyperthermal oscillations (HSOs), a phenomenon termed Sarcomere Chaos with Changes in Calcium Concentration (S4C). This instability is crucial for rapid ventricular diastole in heartbeats.
Area of Science:
- Cardiovascular Physiology
- Biophysics
- Cell Biology
Background:
- Cardiomyocytes exhibit hyperthermal sarcomeric oscillations (HSOs) when heated (38-42°C), characterized by both chaotic instability and homeostatic stability.
- These oscillations are hypothesized to be vital for the rapid ventricular expansion during cardiac diastole.
Purpose of the Study:
- To investigate the role of calcium concentration fluctuations in sarcomeric instability during HSOs.
- To characterize the phenomenon of chaotic sarcomere instability induced by calcium changes and its physiological relevance.
Main Methods:
- Induction of HSOs in cardiomyocytes via controlled heating.
- Analysis of sarcomere dynamics under varying calcium concentrations.
- Measurement of oscillation amplitude and Lyapunov exponent to quantify instability.
Main Results:
- Calcium concentration fluctuations were found to induce chaotic instability in HSOs, distinct from oscillations under constant calcium.
- This calcium-induced chaotic instability was named Sarcomere Chaos with Changes in Calcium Concentration (S4C).
- S4C exhibits fluctuations in oscillation amplitude and a positive Lyapunov exponent, similar to HSOs, and was observed in electro-mechanical coupling relaxation dynamics.
Conclusions:
- S4C represents a significant sarcomeric property contributing to the dynamic flexibility required for ventricular diastole.
- Understanding S4C provides insight into the physiological function of sarcomeres, particularly their response to calcium signaling during the cardiac cycle.
Keywords:
contraction rhythm homeostasisexcitation–contraction couplinghyperthermal sarcomeric oscillationssarcomere chaosMore Related Videos
11:00Assessment of Sarcoplasmic Reticulum Calcium Reserve and Intracellular Diastolic Calcium Removal in Isolated Ventricular Cardiomyocytes
Published on: September 18, 2017
10.1K
10:05Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging
Published on: June 20, 2016
7.7K
Related Concept Videos
01:25Smooth Muscle Contraction
2.8K
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...
2.8K
01:27Feedback Regulation of Calcium Concentration
3.4K
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...
3.4K
01:26Cross-bridge Cycle
117.3K
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
117.3K
01:16Actin and Myosin in Muscle Contraction
10.3K
Actin and myosin are contractile proteins that form the sarcomere found in skeletal muscle tissues for regulating muscle contraction. Actin, a globular contractile protein, interacts with myosin for muscle contraction. The skeletal tissue appears striped or striated under a microscope due to the repeated arrangement of contractile proteins actin and myosin along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes...
10.3K
01:29Relaxation of Skeletal Muscles
3.2K
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....
3.2K
01:20Excitation-Contraction Coupling in Skeletal Muscles
8.1K
Excitation-contraction coupling is a series of events that occur between generating an action potential and initiating a muscle contraction. It occurs at the triad, a structure found in skeletal muscle fibers that comprise a T-tubule and terminal cisternae of the sarcoplasmic reticulum on each side. These triads are visible in longitudinally sectioned muscle fibers. They are typically located at the A-I junction — the junction between the A and I bands of the sarcomere.
When an action...
When an action...
8.1K