The membrane capacity of mammalian skeletal muscle fibres
Abstract:
Membrane capacity was measured as a function of fibre diameter in mammalian skeletal muscle fibres under normal conditions and under conditions designed to reduce the membrane chloride conductance, i.e. in solutions in which chloride ions were replaced by sulphate or methylsulphate ions, or in normal Krebs solutions containing 2,4-dichlorophenoxyacetic acid (2.5 mM). The experiments were done on rat sternomastoid, extensor digitorum longus and soleus muscle fibres. The average membrane capacity of fibres in each muscle was greater than normal when chloride conductance was reduced and the slope of the relationship between membrane capacity and fibre diameter increased. The results were consistent with the hypothesis that the space constant of the transverse tubule system in mammalian fibres is normally short because the transverse tubule membrane has a high chloride conductance. The experimental results imply that the space constant of the transverse tubule system was less than 40 microns for fibres in normal Krebs solution and greater than 100 microns for fibres with low membrane chloride conductance. The space constant was calculated using measured geometrical parameters of the transverse tubule, and measured membrane conductance, and the values were close to 20 microns for fibres in normal Krebs solution and between 50 and 120 microns for fibres with low chloride conductance.
More Related Videos
11:30Measurement of Maximum Isometric Force Generated by Permeabilized Skeletal Muscle Fibers
Published on: June 16, 2015
08:12Intact Short, Intermediate, and Long Skeletal Muscle Fibers Obtained by Enzymatic Dissociation of Six Hindlimb Muscles of Mice: Beyond Flexor Digitorum Brevis
Published on: December 1, 2023
Related Concept Videos
Skeletal Muscle Anatomy
Overview of Skeletal Muscle
Microscopic Anatomy of Skeletal Muscles
The muscle sarcolemma is a plasma membrane enclosing each muscle cell that conducts electrical signals called action potentials. The sarcolemma extends into the cell to form T-tubules, ensuring the neural impulses are uniformly distributed across the entire muscle...
Generation of Action Potential in Skeletal Muscles
Like neurons, muscle cells are also regarded as excitable due to their capacity to change in response to stimuli, primarily due to voltage-gated ion channels embedded in their plasma membranes, which get activated by alterations in the cell's...
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.
Specialized Characteristics of Cardiac Muscles
Cardiac muscle cells are smaller than skeletal muscles, averaging 10–20 mm in diameter and 50–100 mm in length. However, they have large energy demands for continuous contraction and relaxation. This energy is almost exclusively derived from aerobic metabolism of energy reserves in...
