Calcium Signaling in Isolated Skeletal Muscle Fibers Investigated Under "Silicone Voltage-Clamp" Conditions

2004 ◽  
Vol 40 (2) ◽  
pp. 225-236 ◽  
Author(s):  
Claude Collet ◽  
Sandrine Pouvreau ◽  
Laszlo Csernoch ◽  
Bruno Allard ◽  
Vincent Jacquemond
Keyword(s):  
Skeletal Muscle ◽  
Calcium Signaling ◽  
Voltage Clamp ◽  
Muscle Fibers ◽  
Skeletal Muscle Fibers

scholarly journals Optical signals from surface and T system membranes in skeletal muscle fibers. Experiments with the potentiometric dye NK2367.

1982 ◽  
Vol 80 (2) ◽  
pp. 203-230 ◽  
Author(s):  
J A Heiny ◽  
J Vergara
Keyword(s):  
Skeletal Muscle ◽  
Voltage Clamp ◽  
Surface Membrane ◽  
Muscle Fibers ◽  
Optical Signal ◽  
Intensity Change ◽  
Optical Signals ◽  
Potential Control ◽  
Skeletal Muscle Fibers ◽  
T System

Absorbance signals were recorded from cut single skeletal muscle fibers stained with the nonpenetrating potentiometric dye NK2367 and mounted in a three-vaseline-gap voltage clamp. The characteristics of the optical signals recorded under current and voltage-clamp conditions were studied at various wavelengths between 500 and 800 nm using unpolarized light. Our results indicate that the absorbance signals recorded with this dye reflect potential changes across both the surface and T system membranes and that the relative contribution of each of these membrane compartments to the total optical change is strongly wavelength dependent. A peak intensity change was detected at 720 nm for the surface membrane signal and at 670 nm for the T system. Evidence for this wavelength-dependent separation derives from an analysis of the kinetics and voltage dependence of the optical signals at different wavelengths, and results obtained in detubulated fibers. The 670-nm optical signal was used to demonstrate the lack of potential control in the T system by the voltage clamp and the effect of a tetrodotoxin (TTX)-sensitive sodium conductance on tubular depolarization.

scholarly journals Arsenazo III and antipyrylazo III calcium transients in single skeletal muscle fibers.

1982 ◽  
Vol 79 (4) ◽  
pp. 679-707 ◽  
Author(s):  
P Palade ◽  
J Vergara
Keyword(s):  
Skeletal Muscle ◽  
Voltage Clamp ◽  
Spectral Characteristics ◽  
Muscle Fibers ◽  
Calcium Transients ◽  
Arsenazo Iii ◽  
Tension Development ◽  
Skeletal Muscle Fibers ◽  
Concentration Changes

The metallochrome calcium indicators arsenazo III and antipyrylazo III have been introduced individually into cut single frog skeletal muscle fibers from which calcium transients have been elicited either by action potential stimulation or by voltage-clamp pulses of up to 50 ms in duration. Calcium transients recorded with both dyes at selected wavelengths have similar characteristics when elicited by action potentials. Longer voltage-clamp pulse stimulation reveals differences in the late phases of the optical signals obtained with the two dyes. The effects of different tension blocking methods on Ca transients were compared experimentally. Internal application of EGTA at concentrations up to 3 mM was demonstrated to be efficient in blocking movement artifacts without affecting Ca transients. Higher EGTA concentrations affect the Ca signals' characteristics. Differential effects of internally applied EGTA on tension development as opposed to calcium transients suggest that diffusion with binding from Ca++ release sites to filament overlap sites may be significant. The spectral characteristics of the absorbance transients recorded with arsenazo III suggest that in situ recorded signals cannot be easily interpreted in terms of Ca concentration changes. A more exhaustic knowledge of the dye chemistry and/or in situ complications in the use of the dye will be necessary.

scholarly journals An improved vaseline gap voltage clamp for skeletal muscle fibers.

1976 ◽  
Vol 67 (3) ◽  
pp. 265-293 ◽  
Author(s):  
B Hille ◽  
D T Campbell
Keyword(s):  
Skeletal Muscle ◽  
Voltage Clamp ◽  
Sodium Current ◽  
Muscle Fibers ◽  
Complex Impedance ◽  
Sodium Currents ◽  
Disk Model ◽  
Transverse Tubular System ◽  
Skeletal Muscle Fibers ◽  
Tubular System

A Vaseline gap potentiometric recording and voltage clamp method is developed for frog skeletal muscle fibers. The method is based on the Frankenhaeuser-Dodge voltage clamp for myelinated nerve with modifications to improve the frequency response, to compensate for external series resistance, and to compensate for the complex impedance of the current-passing pathway. Fragments of single muscle fibers are plucked from the semitendinosus muscle and mounted while depolarized by a solution like CsF. After Vaseline seals are formed between fluid pools, the fiber ends are cut once again, the central region is rinsed with Ringer solution, and the feedback amplifiers are turned on. Errors in the potential and current records are assessed by direct measurements with microelectrodes. The passive properties of the preparation are simulated by the "disk" equivalent circuit for the transverse tubular system and the derived parameters are similar to previous measurements with microelectrodes. Action potentials at 5 degrees C are long because of the absence of delayed rectification. Their shape is approximately simulated by solving the disk model with sodium permeability in the surface and tubular membranes. Voltage clamp currents consist primarily of capacity currents and sodium currents. The peak inward sodium current density at 5 degrees C is 3.7 mA/cm2. At 5 degrees C the sodium currents are smoothly graded with increasing depolarization and free of notches suggesting good control of the surface membrane. At higher temperatures a small, late extra inward current appears for small depolarizations that has the properties expected for excitation in the transverse tubular system. Comparison of recorded currents with simulations shows that while the transverse tubular system has regenerative sodium currents, they are too small to make important errors in the total current recorded at the surface under voltage clamp at low temperature. The tubules are definitely not under voltage clamp control.

The “KIMWIPE” Effect in Ultra-Thin Cryosections

1985 ◽  
Vol 43 ◽  
pp. 458-459
Author(s):  
I. Taylor ◽  
P. Ingram ◽  
J.R. Sommer
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Muscle Fibers ◽  
Ice Crystals ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Thin Sections ◽  
Skeletal Muscle Fibers ◽  
Freeze Dried ◽  
Ice Crystal Formation

In studying quick-frozen single intact skeletal muscle fibers for structural and microchemical alterations that occur milliseconds, and fractions thereof, after electrical stimulation, we have developed a method to compare, directly, ice crystal formation in freeze-substituted thin sections adjacent to all, and beneath the last, freeze-dried cryosections. We have observed images in the cryosections that to our knowledge have not been published heretofore (Figs.1-4). The main features are that isolated, sometimes large regions of the sections appear hazy and have much less contrast than adjacent regions. Sometimes within the hazy regions there are smaller areas that appear crinkled and have much more contrast. We have also observed that while the hazy areas remain still, the regions of higher contrast visibly contract in the beam, often causing tears in the sections that are clearly not caused by ice crystals (Fig.3, arrows).

Effect of External Calcium and other Divalent Cations on K+ Contractures in Denervated Slow Skeletal Muscle Fibers of the Frog

2019 ◽  
Author(s):  
Leonardo Hernández
Keyword(s):  
Skeletal Muscle ◽  
Binding Capacity ◽  
Divalent Cations ◽  
Muscle Fibers ◽  
Free Calcium ◽  
Slow Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Free Calcium Concentration ◽  
Chronic Denervation ◽  
Denervated Muscles

The influence of Ca2+ and other divalent cations on contractile responses of slow skeletal muscle fibers of the frog (Rana pipiens) under conditions of chronic denervation was investigated.Isometric tension was recorded from slow bundles of normal and denervated cruralis muscle in normal solution and in solutions with free calcium concentration solution or in solutions where other divalent cations (Sr2+, Ni2+, Co2+ or Mn2+) substituted for calcium. In the second week after nerve section, in Ca2+-free solutions, we observed that contractures (evoked from 40 to 80 mM-K+) of non-denervated muscles showed significantly higher tensions (p<0.05), than those from denervated bundles. Likewise, in solutions where calcium was substituted by all divalent cations tested, with exception of Mn2+, the denervated bundles displayed lower tension than non-denervated, also in the second week of denervation. In this case, the Ca2+ substitution by Sr2+ caused the higher decrease in tension, followed by Co2+ and Ni2+, which were different to non-denervated bundles, as the lowest tension was developed by Mn2+, followed by Co2+, and then Ni2+ and Sr2+. After the third week, we observed a recovery in tension. These results suggest that denervation altering the binding capacity to divalent cations of the voltage sensor.

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