Faculty Opinions recommendation of Examination of the subsarcolemmal tubular system of mammalian skeletal muscle fibers.

2013 ◽  
Author(s):  
Graham Lamb
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Mammalian Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Tubular System

scholarly journals Chloride currents from the transverse tubular system in adult mammalian skeletal muscle fibers

2010 ◽  
Vol 137 (1) ◽  
pp. 21-41 ◽  
Author(s):  
Marino DiFranco ◽  
Alvaro Herrera ◽  
Julio L. Vergara
Keyword(s):  
Skeletal Muscle ◽  
Time Course ◽  
Muscle Fibers ◽  
Optical Data ◽  
Mammalian Skeletal Muscle ◽  
Chloride Currents ◽  
Actual Distribution ◽  
Transverse Tubular System ◽  
Skeletal Muscle Fibers ◽  
Tubular System

Chloride fluxes are the main contributors to the resting conductance of mammalian skeletal muscle fibers. ClC-1, the most abundant chloride channel isoform in this preparation, is believed to be responsible for this conductance. However, the actual distribution of ClC-1 channels between the surface and transverse tubular system (TTS) membranes has not been assessed in intact muscle fibers. To investigate this issue, we voltageclamped enzymatically dissociated short fibers using a two-microelectrode configuration and simultaneously recorded chloride currents (ICl) and di-8-ANEPPS fluorescence signals to assess membrane potential changes in the TTS. Experiments were conducted in conditions that blocked all but the chloride conductance. Fibers were equilibrated with 40 or 70 mM intracellular chloride to enhance the magnitude of inward ICl, and the specific ClC-1 blocker 9-ACA was used to eliminate these currents whenever necessary. Voltage-dependent di-8-ANEPPS signals and ICl acquired before (control) and after the addition of 9-ACA were comparatively assessed. Early after the onset of stimulus pulses, di-8-ANEPPS signals under control conditions were smaller than those recorded in the presence of 9-ACA. We defined as attenuation the normalized time-dependent difference between these signals. Attenuation was discovered to be ICl dependent since its magnitude varied in close correlation with the amplitude and time course of ICl. While the properties of ICl, and those of the attenuation seen in optical records, could be simultaneously predicted by model simulations when the chloride permeability (PCl) at the surface and TTS membranes were approximately equal, the model failed to explain the optical data if PCl was precluded from the TTS membranes. Since the ratio between the areas of TTS membranes and the sarcolemma is large in mammalian muscle fibers, our results demonstrate that a significant fraction of the experimentally recorded ICl arises from TTS contributions.

scholarly journals Examination of the Subsarcolemmal Tubular System of Mammalian Skeletal Muscle Fibers

2013 ◽  
Vol 104 (11) ◽  
pp. L19-L21 ◽  
Author(s):  
Isuru D. Jayasinghe ◽  
Harriet P. Lo ◽  
Garry P. Morgan ◽  
David Baddeley ◽  
Robert G. Parton ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Mammalian Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Tubular System

The Adaptive Potential of Skeletal Muscle Fibers

2002 ◽  
Vol 27 (4) ◽  
pp. 423-448 ◽  
Author(s):  
Dirk Pette
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Protein Isoforms ◽  
Mammalian Skeletal Muscle ◽  
Adaptive Potential ◽  
Hybrid Fibers ◽  
Neuromuscular Activity ◽  
Skeletal Muscle Fibers ◽  
Initial Location

Mammalian skeletal muscle fibers display a great adaptive potential. This potential results from the ability of muscle fibers to adjust their molecular, functional, and metabolic properties in response to altered functional demands, such as changes in neuromuscular activity or mechanical loading. Adaptive changes in the expression of myofibrillar and other protein isoforms result in fiber type transitions. These transitions occur in a sequential order and encompass a spectrum of pure and hybrid fibers. Depending on the quality, intensity, and duration of the alterations in functional demand, muscle fibers may undergo functional transitions in the direction of slow or fast, as well as metabolic transitions in the direction of aerobic-oxidative or glycotytic. The maximum range of possible transitions in either direction depends on the fiber phenotype and is determined by its initial location in the fiber spectrum. Key words: Ca-sequestering proteins, energy metabolism, fiber type transition, myofibrillar protein isofonns, myosin, neuromuscular activity

scholarly journals Calcium Sparklets in Intact Mammalian Skeletal Muscle Fibers Expressing the Embryonic CaV1.1 Splice Variant

2015 ◽  
Vol 108 (2) ◽  
pp. 504a
Author(s):  
Beatrix Dienes ◽  
Nasreen Sultana ◽  
Janos Vincze ◽  
Monika Sztretye ◽  
Peter Szentesi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Splice Variant ◽  
Muscle Fibers ◽  
Mammalian Skeletal Muscle ◽  
Skeletal Muscle Fibers

scholarly journals The Capacitance of Skeletal Muscle Fibers in Solutions of Low Ionic Strength

1972 ◽  
Vol 59 (3) ◽  
pp. 347-359 ◽  
Author(s):  
P. C. Vaughan ◽  
J. N. Howell ◽  
R. S. Eisenberg
Keyword(s):  
Skeletal Muscle ◽  
Ionic Strength ◽  
Surface Membrane ◽  
Muscle Fibers ◽  
External Solution ◽  
Rectangular Pulse ◽  
Bathing Solution ◽  
Skeletal Muscle Fibers ◽  
Tubular System ◽  
Low Ionic Strength

The capacitance of skeletal muscle fibers was measured by recording with one microelectrode the voltage produced by a rectangular pulse of current applied with another microelectrode. The ionic strength of the bathing solution was varied by isosmotic replacement of NaCl with sucrose, the [K] [Cl] product being held constant. The capacitance decreased with decreasing ionic strength, reaching a value of some 2 µF/cm2 in solutions of 30 mM ionic strength, and not decreasing further in solutions of 15 mM ionic strength. The capacitance of glycerol-treated fibers did not change with ionic strength and was also some 2 µF/cm2. It seems likely that lowering the ionic strength reduces the capacitance of the tubular system (defined as the charge stored in the tubular system), and that the 2 µF/cm2 which is insensitive to ionic strength is associated with the surface membrane. The tubular system is open to the external solution in low ionic strength solutions since peroxidase is able to diffuse into the lumen of the tubules. Twitches and action potentials were also recorded from fibers in low ionic strength solutions, even though the capacitance of the tubular system was very small in these solutions. This finding can be explained if there is an action potential—like mechanism in the tubular membrane.

scholarly journals Factors affecting SOCE activation in mammalian skeletal muscle fibers

2009 ◽  
Vol 59 (4) ◽  
pp. 317-328 ◽  
Author(s):  
Pura Bolaños ◽  
Alis Guillén ◽  
Reinaldo DiPolo ◽  
Carlo Caputo
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Mammalian Skeletal Muscle ◽  
Factors Affecting ◽  
Skeletal Muscle Fibers
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