scholarly journals Action potentials of isolated single muscle fibers recorded by potential-sensitive dyes.

1980 ◽  
Vol 76 (6) ◽  
pp. 729-750 ◽  
Author(s):  
S Nakajima ◽  
A Gilai
Keyword(s):  
Action Potentials ◽  
Light Transmission ◽  
Surface Membrane ◽  
Muscle Fibers ◽  
Single Muscle ◽  
Squid Axon ◽  
Vertebrate Muscle ◽  
Tubular System ◽  
The Difference ◽  
Stimulation Of

Light transmission changes upon massive stimulation of single muscle fibers of Xenopus were studied with the potential-sensitive nonpermeant dyes, merocyanine rhodanine (WW375) and merocyanine oxazolone (NK2367). Upon stimulation an absorption change (wave a) occurred, which probably represents the sum of action potentials in the transverse tubules and surface membrane. In WW375-stained fibers wave a is a decrease in transmission over the range of 630 to 730 nm (with NK2367, over the range of 590 to 700 nm) but becomes an increase outside this range, thus showing a triphasic spectral pattern. This spectrum differs from that of the squid axon, in which depolarization produces only an increase in transmission over the whole range of wavelengths (Ross et al. 1977. J. Membr. Biol. 33:141-183). When wave a was measured at the edge of the fiber to obtain more signal from the surface membrane, the spectrum did not seem to differ markedly from that obtained from the entire width of the fiber. Thus, the difference in the spectrum between the squid axon and the vertebrate muscle cannot be attributed to the presence of the tubular system.

Contraction-induced injury to single muscle fibers: velocity of stretch does not influence the force deficit

1998 ◽  
Vol 275 (6) ◽  
pp. C1548-C1554 ◽  
Author(s):  
Gordon S. Lynch ◽  
John A. Faulkner
Keyword(s):  
Null Hypothesis ◽  
Muscle Injury ◽  
Isometric Force ◽  
Muscle Fibers ◽  
Single Muscle ◽  
Control Value ◽  
Severity Of Injury ◽  
Before And After ◽  
The Difference ◽  
Permeabilized Fibers

We tested the null hypothesis that the severity of injury to single muscle fibers following a single pliometric (lengthening) contraction is not dependent on the velocity of stretch. Each single permeabilized fiber obtained from extensor digitorum longus muscles of rats was maximally activated and then exposed to a single stretch of either 5, 10, or 20% strain [% of fiber length ( L f)] at a velocity of 0.5, 1.0, or 2.0 L f /s. The force deficit, the difference between maximum tetanic isometric force (Po) before and after the stretch expressed as a percentage of the control value for Po before the stretch, provided an estimate of the magnitude of muscle injury. Despite a fourfold range from the lowest to the highest velocities, force deficits were not different among stretches of the same strain. At stretches of 20% strain, even an eightfold range of velocities produced no difference in the force deficit, although 40% of the fibers were torn apart at a velocity of 4 L f /s. We conclude that, within the range of velocities tolerated by single permeabilized fibers, the severity of contraction-induced injury is not related to the velocity of stretch.

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 Radial propagation of muscle action potential along the tubular system examined by potential-sensitive dyes.

1980 ◽  
Vol 76 (6) ◽  
pp. 751-762 ◽  
Author(s):  
S Nakajima ◽  
A Gilai
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Time Course ◽  
Surface Membrane ◽  
Simultaneous Recording ◽  
Conduction Delay ◽  
Muscle Action Potential ◽  
Tubular System ◽  
Intracellular Action ◽  
T System

Isolated single (Xenopus) muscle fibers were stained with a non-permeant potential-probing dye, merocyanine rhodanine (WW375) or merocyanine oxazolone (NK2367). When the fiber was massively stimulated, an absorption change (wave a), which seemed to reflect the action potential, occurred. Simultaneous recording of optical changes and intracellular action potentials revealed that the time-course of wave a was slower than the action potential: the peak of wave a was attained at 1 ms, and the peak of action potential was reached at 0.5 ms after the stimulation. This difference suggests that wave a represents the potential changes of the whole tubular membrane and the surface membrane, whereas the action potential represents a surface potential change. This idea was substantiated by recording absorption signals preferentially from the surface membrane by recording the absorption changes at the edge of the fiber. Wave a obtained by this method was as quick as the intracellular action potential. The value of radial conduction velocity of action potential along the T system, calculated by comparing the action potential with wave a, was 6.4 cm/s at 24.5 degrees C, in fair agreement with González-Serratos (1971. J. Physiol. [Lond.]. 212:777-799). The shape of wave a suggests the existence of an access delay (a conduction delay at the orifice of the T system) of 130 microseconds.

scholarly journals Voltage Clamp Experiments on Single Muscle Fibers of Rana pipiens

1972 ◽  
Vol 60 (1) ◽  
pp. 1-19 ◽  
Author(s):  
L. E. Moore
Keyword(s):  
Voltage Clamp ◽  
Rana Pipiens ◽  
Muscle Fibers ◽  
Petroleum Jelly ◽  
Single Muscle ◽  
Transverse Tubular System ◽  
Anomalous Rectification ◽  
Outward Currents ◽  
Delayed Rectification ◽  
Tubular System

A voltage clamp for single muscle fibers has been developed. Stability of the system was achieved when an artificial node was created by enclosing a single muscle fiber in a petroleum jelly seal which served as an analogue of the myelin sheath. Typical voltage clamp records were obtained with large inward transient currents followed by a delayed rectification of the outward currents. These currents looked qualitatively similar when the transverse tubular system was destroyed. Errors in current measurement, especially those due to anomalous rectification, are discussed.

scholarly journals The effect of evocalcet on vagus nerve activity of the gastrointestinal tract in miniature pigs

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245785
Author(s):  
Shin Tokunaga ◽  
Takehisa Kawata
Keyword(s):  
Vagus Nerve ◽  
Action Potentials ◽  
Vehicle Group ◽  
Gi Tract ◽  
Direct Stimulation ◽  
Miniature Pigs ◽  
Nerve Action ◽  
Calcimimetic Agents ◽  
The Difference ◽  
Stimulation Of

Evocalcet is a novel calcimimetic agent with fewer gastrointestinal (GI) adverse effects compared to cinacalcet. Although it is thought that cinacalcet induces GI side effects through the direct stimulation of the calcium receptor (CaR) expressed in the GI tract, the differences in the direct stimulatory effects of these two drugs on the GI tract have not been reported. In this study, we analyzed the difference in the GI effects of these two calcimimetic agents using miniature pigs by detecting vagus nerve stimulation after oral administration of the agents. Although cinacalcet induced vomiting in miniature pigs, evocalcet never induced emetic symptoms. A significant increase in the vagus nerve action potentials was observed after the administration of cinacalcet. Although the increase of that after the administration of evocalcet was mild and not significant in comparison to that in the vehicle group, it was not significantly different from the vagus nerve action potentials after cinacalcet treatment.

scholarly journals Effects of Caffeine on Crayfish Muscle Fibers

1970 ◽  
Vol 55 (5) ◽  
pp. 640-664 ◽  
Author(s):  
Dante J. Chiarandini ◽  
John P. Reuben ◽  
Philip W. Brandt ◽  
Harry Grundfest
Keyword(s):  
Time Course ◽  
Muscle Fibers ◽  
Resting Potential ◽  
Induced Responses ◽  
Single Muscle ◽  
Transverse Tubular System ◽  
Crayfish Muscle ◽  
Number Of Factors ◽  
Tubular System

Contractions are evoked in single muscle fibers of crayfish by intracellular as well as extracellular applications of caffeine. Responses to external applications in concentrations above 2 mM could be induced indefinitely. With concentrations above 5 mM the caffeine-induced responses were highly repeatable. Tensions were transient even when the caffeine remained in the bath. There was no change in resting potential, but during the contraction the effective resistance decreased about 10%. A number of factors (change in pH, Ca, K, and Cl) modified the responses. The time course of the tension was greatly prolonged when the transverse tubular system (TTS) was s swollen and was again shortened when the TTS was caused to shrink. An increased permeability to Ca induced by caffeine was evidenced by the transformation of the normally graded electrical responses to Ca spikes, which are insensitive to tetrodotoxin. The overshoot is a function of both external Ca and caffeine. A 10-fold change in Ca changed the overshoot by 19 mv in the presence of 10 mM caffeine and by 29 mv in 80 mM caffeine. The role of the increased permeability to Ca for caffeine-induced contractions will be analyzed in the accompanying paper.

scholarly journals CORRELATED MORPHOLOGICAL AND PHYSIOLOGICAL STUDIES ON ISOLATED SINGLE MUSCLE FIBERS

1968 ◽  
Vol 38 (1) ◽  
pp. 115-129 ◽  
Author(s):  
Philip W. Brandt ◽  
John P. Reuben ◽  
Harry Grundfest
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Current Flow ◽  
Muscle Fibers ◽  
Single Muscle ◽  
Unit Membrane ◽  
Membrane Phase ◽  
Transverse Tubular System ◽  
Contraction Coupling ◽  
Cytoplasmic Material ◽  
Tubular System

Living muscle fibers of crayfish become dark during efflux of Cl-. This change in appearance is correlated with occurrence of vacuolation in the fixed fibers. The vacuoles begin at and are mainly confined to the terminals of the transverse tubular system (TTS) which are in diadic contact with the sarcoplasmic reticulum (SR). In electron micrographs swellings more than 1 µ in diameter may be seen connected to the sarcolemma or sarcolemmal invaginations by relatively unswollen tubules about 300–500 A wide. Darkening of the living fibers can be reversed by causing an influx of Cl-. Vacuoles are then absent in the fixed preparations. These findings accord with the conclusion that the membrane of the TTS is anion permselective. Localization of the selectivity to the membrane of the terminals of the TTS strengthens the hypothesis that a channeling of current flow is responsible for initiation of excitation-contraction coupling. During the swelling, and upon its reversal, the area of the membrane of the terminals must change reversibly by about two to four orders of magnitude. The absence of changes in the dimensions of the unit membrane indicates that the expansion of the membrane and its subsequent shrinkage involve reversible incorporation of cytoplasmic material into the membrane phase.

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