Inhibition of tetanus tension by elevated extracellular calcium concentration

1981 ◽  
Vol 240 (5) ◽  
pp. C193-C200 ◽  
Author(s):  
J. N. Howell ◽  
K. W. Snowdowne
Keyword(s):  
Skeletal Muscle ◽  
Action Potentials ◽  
Calcium Concentration ◽  
Extracellular Calcium ◽  
Frog Skeletal Muscle ◽  
Transverse Tubular System ◽  
Microelectrode Recordings ◽  
Tubular System ◽  
Osmotic Effects ◽  
Reversible Reduction

Extracellular [Ca2+] in the range of 5-20 mM produces a concentration-dependent reversible reduction in tetanus tension in single frog skeletal muscle fibers. Both peak tension and ability to sustain tension during tetanus is reduced. The effect is unrelated to osmotic effects and independent of stimulation frequency in the range 100-200 Hz. The effect occurs both at 8 and 24 degrees C. Tetanus tension is most strongly inhibited by elevated extracellular [Ca2+] at short muscle lengths, but the effect can be seen at all lengths. Microelectrode recordings during tetanus indicate that action potentials remain undiminished in amplitude and duration throughout the tetanus. The evidence suggests that the inhibition results from a failure of action potentials propagation within the transverse tubular system.

scholarly journals Inward rectification in the transverse tubular system of frog skeletal muscle studied with potentiometric dyes.

1985 ◽  
Vol 359 (1) ◽  
pp. 269-291 ◽  
Author(s):  
F M Ashcroft ◽  
J A Heiny ◽  
J Vergara
Keyword(s):  
Skeletal Muscle ◽  
Inward Rectification ◽  
Frog Skeletal Muscle ◽  
Transverse Tubular System ◽  
Tubular System

scholarly journals Significance of Transverse Tubular System in Determining the Contractility of Frog Skeletal Muscle

1972 ◽  
Vol 48 (7) ◽  
pp. 539-543
Author(s):  
Masahiro FUJINO ◽  
Sumiko FUJINO ◽  
Toshio YAMAGUCHI
Keyword(s):  
Skeletal Muscle ◽  
Frog Skeletal Muscle ◽  
Transverse Tubular System ◽  
Tubular System

scholarly journals The Radial Variation of Potential in the Transverse Tubular System of Skeletal Muscle

1971 ◽  
Vol 58 (6) ◽  
pp. 700-701 ◽  
Author(s):  
R. S. Eisenberg ◽  
L. L. Constantin
Keyword(s):  
Skeletal Muscle ◽  
Radial Variation ◽  
Transverse Tubular System ◽  
Tubular System

An investigation of the activity of opiate drug receptors located on frog skeletal muscle fibre membrane

1978 ◽  
Vol 56 (3) ◽  
pp. 501-508 ◽  
Author(s):  
G. B. Frank ◽  
J. Marwaha
Keyword(s):  
Skeletal Muscle ◽  
Action Potentials ◽  
Skeletal Muscle Fibre ◽  
Second Phase ◽  
Frog Skeletal Muscle ◽  
Potential Production ◽  
Low Concentrations ◽  
Drug Receptors ◽  
Frog Sartorius ◽  
Opiate Drug

Extracellular and intracellular microelcctrode studies were conducted to test the actions and interactions of opiate agonists, antagonists, and procaine on action potentials in frog sartorius muscles. Extracellular studies showed that morphine, methadone, propoxyphene, and procaine all depressed action potential production. Low concentrations of naloxone or naltrexone antagonized the excitability depression produced by the three opiate agonists but not the depression produced by procaine. Intracellular studies revealed that certain concentrations of the opiate agonists produced a biphasic decline in the stimulus-induced increase in sodium conductance (gNa). Naloxone or naltrexone antagonized only the second phase of this decline. These results show that part of the excitability depression produced by opiate agonists is due to an action on opiate drug receptors.

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.

Sign in / Sign up

Export Citation Format

Share Document