Related Experiment Video
Updated: May 10, 2026
14:02
Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Muscle contraction and the elasticity-mediated crosstalk effect
1Department of Biomedical Engineering, Ben Gurion University of the Negev, Be'er Sheva 84105, Israel.
Summary
Elasticity-mediated crosstalk (EMC) in myosin II motors impacts motor attachment probability in sarcomeres. This effect, significant in larger systems, explains muscle variability and relates to Hill
Area of Science:
- Muscle physiology
- Biophysics
- Molecular motor function
Background:
- Cooperative action of molecular motors, like myosin II, is crucial for cellular functions.
- Elasticity-mediated crosstalk (EMC) arises from collective tensile stress generated by myosin II motors in actin filaments.
- Sarcomeres, the contractile units of skeletal muscles, rely on coordinated motor activity.
Purpose of the Study:
- To investigate the influence of the EMC effect on sarcomere structure and function using statistical mechanics.
- To analyze how EMC affects motor attachment probability within the sarcomere.
- To explore the relationship between motor duty ratio, tension, and muscle contraction dynamics.
Main Methods:
- Statistical mechanical analysis of myosin II motor behavior within actin filaments.
- Modeling the EMC effect on motor attachment probabilities at different sarcomere locations.
- Investigating the connection between motor duty ratio, tension, and established muscle contraction models.
Main Results:
- EMC increases motor attachment probability near sarcomere ends and decreases it in the center, potentially impairing motor cooperation.
- The impact of EMC becomes significant only in systems larger than typical skeletal muscle sarcomeres.
- A close relationship was found between the observed increase in motor duty ratio with tension and Hill's equation for muscle contraction.
Conclusions:
- The EMC effect's system-size dependency offers an explanation for the low variability of sarcomeres in vertebrate skeletal muscles.
- EMC may play a role in regulating motor coordination, with its significance dependent on the scale of the system.
- The study reinforces the connection between microscopic motor behavior, macroscopic muscle contraction, and established physiological equations like Hill's equation.
Related Concept Videos
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...
01:20Excitation-Contraction Coupling in Skeletal Muscles
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 potential...
When an action potential...
01:26Cross-bridge Cycle
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.
01:25Overview of Muscle Tissues
The human body has three types of muscle tissue: skeletal, smooth, and cardiac. Each class has unique properties that enable them to perform specific functions. However, all muscle tissues share certain properties, including elasticity, contractility, and excitability.
Elasticity
Elasticity is the ability of muscles to stretch and return to their original shape. This property is partly due to elastic fibers — macromolecules that run through the muscles. These fibers are firm and resilient,...
Elasticity
Elasticity is the ability of muscles to stretch and return to their original shape. This property is partly due to elastic fibers — macromolecules that run through the muscles. These fibers are firm and resilient,...
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.
01:10Muscle Contraction
In skeletal muscles, acetylcholine is released by nerve terminals at the motor endplate—the point of synaptic communication between motor neurons and muscle fibers. The binding of acetylcholine to its receptors on the sarcolemma allows entry of sodium ions into the cell and triggers an action potential in the muscle cell. Thus, electrical signals from the brain are transmitted to the muscle. Subsequently, the enzyme acetylcholinesterase breaks down acetylcholine to prevent excessive muscle...