scholarly journals Swelling of the Transverse Tubular System in Frog Sartorius

1969 ◽  
Vol 54 (2) ◽  
pp. 166-177 ◽  
Author(s):  
Stanley I. Rapoport ◽  
L. D. Peachey ◽  
D. A. Goldstein
Keyword(s):  
Electron Microscopy ◽  
Ionic Strength ◽  
Sucrose Concentration ◽  
Time Dependent ◽  
Bathing Solution ◽  
Transverse Tubular System ◽  
Fixed Charges ◽  
Degree Of Swelling ◽  
Tubular System ◽  
Frog Sartorius

Electron microscopy shows that the transverse tubular system of frog sartorius swells in Ringer fluid in which NaCl is partially replaced by sucrose (sucrose isotonic solutions). At constant tonicity, the degree of swelling is roughly proportional to the decrease in ionic strength and to the sucrose concentration of the bathing solution. Swelling is time-dependent and reversible within 2 hr. The late after potential which follows a train of impulses is prolonged with swelling, but not to the extent expected from the model of Adrian and Freygang. This discrepancy remains unexplained, as does the mechanism of swelling of the transverse tubular system, although some suggestions are offered. One is that the transverse tubular system contains fixed charges and swells like a fixed charge gel.

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 The Relation Between the Late After-Potential and the Size of the Transverse Tubular System of Frog Muscle

1964 ◽  
Vol 48 (2) ◽  
pp. 235-263 ◽  
Author(s):  
W. H. Freygang ◽  
D. A. Goldstein ◽  
D. C. Hellam ◽  
L. D. Peachey
Keyword(s):  
Experimental Data ◽  
Calculated Data ◽  
Frog Muscle ◽  
Free Solution ◽  
Electron Microscopic ◽  
Chloride Solutions ◽  
Transverse Tubular System ◽  
Tubular System ◽  
Low Potassium ◽  
Frog Sartorius

This is an investigation of the effects on the late after-potential of immersing frog sartorius muscles in three kinds of modified Ringer's fluid; hypertonic, low chloride, and potassium-free. The late after-potential has been attributed to the depolarizing effect of an accumulation of potassium, during a preceding train of impulses, in the intermediary space of the model of a muscle fiber proposed by Adrian and Freygang. Both the hypertonic and low chloride solutions prolonged the late after-potential reversibly and the potassium-free solution shortened it. The effect of the low potassium solution fitted those data calculated from the model, but the effect of the hypertonic and low chloride solutions required an increase in size of the intermediary space of the model in order to fit the calculated data. An electron microscopic study of the muscles showed that the size of the transverse tubular system changed reversibly in the hypertonic and low chloride solutions in almost the amount necessary to fit the experimental data to the calculated data. This agreement between the change in size of the transverse tubular system and that of the intermediary space indicates that the intermediary space may be the transverse tubular system.

scholarly journals ON THE STRUCTURAL CONTINUITIES OF THE TRANSVERSE TUBULAR SYSTEM OF RABBIT AND HUMAN MYOCARDIAL CELLS

1963 ◽  
Vol 16 (2) ◽  
pp. 297-313 ◽  
Author(s):  
Douglas A. Nelson ◽  
Ellis S. Benson
Keyword(s):  
Extracellular Fluid ◽  
Sartorius Muscle ◽  
Electron Microscopic ◽  
Transverse Tubular System ◽  
Tubular System ◽  
Time Distance ◽  
Kinetics Of ◽  
Frog Sartorius ◽  
Human Myocardial Cells ◽  
Physiologic Data

An electron microscopic study of rabbit and human myocardium provides further evidence of the existence of two distinct components of the sarcoplasmic reticulum. A thin-walled tubular system (termed longitudinal system) is arranged in anastomosing channels sur-surrounding each sarcomere and has transverse and possibly also longitudinal connections with the tubules of adjacent sarcomeres. A thick-walled tubular system traverses the myofiber transversely at the level of the Z lines of the myofibrils. The structure of these tubules very closely resembles that of deep sarcolemmal invaginations. Indeed, the membranes of the tubules appear to be continuous with the sarcolemma in favorable sections so that there seems to be an extension of the cell membrane and extracellular fluid to all depths of the myocardial fiber. Certain physiologic data which support this concept are discussed. The calculations of A. V. Hill comparing the kinetics of diffusion and the time-distance relationships between excitation and activation in frog sartorius muscle are reconsidered for cardiac muscle.

scholarly journals Some Relations between Changes in the Linear Electrical Properties of Striated Muscle Fibers and Changes in Ultrastructure

1967 ◽  
Vol 50 (10) ◽  
pp. 2437-2458 ◽  
Author(s):  
W. H. Freygang ◽  
S. I. Rapoport ◽  
L. D. Peachey
Keyword(s):  
Electrical Properties ◽  
Time Constant ◽  
Striated Muscle ◽  
Sartorius Muscle ◽  
Transverse Tubular System ◽  
Tubular System ◽  
In Series ◽  
Striated Muscle Fibers ◽  
Frog Sartorius ◽  
Good Agreement

Some of the linear electrical properties of frog sartorius muscle have been investigated in Ringer's fluid and in a Ringer fluid made hypertonic by the addition of sucrose or NaCl. Electrical constants were determined from measurements of the phase angle of the admittance of a fiber for an applied alternating current, from measurements of the voltage induced by an inward pulse of current, and from measurements of the conduction velocity of the action potential and the time constant of its foot. The dilation of the transverse tubular system induced by the sucrose hypertonic Ringer fluid was correlated with the change in the electrical constants. From this it is concluded that a two time constant equivalent circuit for the membrane, as proposed by Falk and Fatt, is in good agreement with our results. Both the area of the membrane of the transverse tubular system, and the capacity (ce) attributed to it, increased in the sucrose hypertonic Ringer fluid. The resistance re, which is in series with ce, did not fall when the transverse tubular system was dilated and probably is not located in that system.

The effect of nitrate ion on glycerol-treated frog skeletal muscle fibers

1970 ◽  
Vol 48 (12) ◽  
pp. 813-816 ◽  
Author(s):  
A. R. Luff ◽  
H. L. Atwood
Keyword(s):  
Time Constant ◽  
Surface Membrane ◽  
Muscle Fibers ◽  
Effective Resistance ◽  
Sartorius Muscle ◽  
Nitrate Ion ◽  
Transverse Tubular System ◽  
A Value ◽  
Tubular System ◽  
Frog Sartorius

The effect of nitrate ion on glycerol-treated, frog sartorius muscle fibers was investigated. Glycerol treatment alone (which has been shown to disrupt the transverse tubular system of the fiber) caused a considerable reduction in the time constant of the fiber membrane, but the effective resistance was virtually unchanged. Exposure of normal fibers to nitrate ion produced an increase in both the effective resistance and the time constant. Glycerol-treated fibers exposed to nitrate ion showed an increase in both the effective resistance and the time constant. The latter increased to a value in excess of that found in the normal fibers. The effect of nitrate ion on membrane electrical properties appeared to result from its action on the surface membrane as opposed to the transverse tubules.

scholarly journals A STRAND OF CARDIAC MUSCLE

1967 ◽  
Vol 33 (1) ◽  
pp. 103-129 ◽  
Author(s):  
Edward A. Johnson ◽  
Joachim R. Sommer
Keyword(s):  
Electron Microscopy ◽  
Cardiac Muscle ◽  
Papillary Muscle ◽  
Muscle Fibers ◽  
Light And Electron Microscopy ◽  
Rabbit Heart ◽  
Transverse Tubular System ◽  
Fiber Contact ◽  
Tubular System ◽  
Comprehensive Study

The structure of a small strand of rabbit heart muscle fibers (trabecula carnea), 30–80 µ in diameter, has been examined with light and electron microscopy. By establishing a correlation between the appearance of regions of close fiber contact in light and electron microscopy, the extent and distribution of regions of close apposition of fibers has been evaluated in approximately 200 µ length of a strand. The distribution of possible regions of resistive coupling between fibers has been approximated by a model system of cables. The theoretical linear electrical properties of such a system have been analyzed and the implications of the results of this analysis are discussed. Since this preparation is to be used for correlated studies of the electrical, mechanical, and cytochemical properties of cardiac muscle, a comprehensive study of the morphology of this preparation has been made. The muscle fibers in it are distinguished from those of the rabbit papillary muscle, in that they have no triads and have a kind of mitochondrion not found in papillary muscle. No evidence of a transverse tubular system was found, but junctions of cisternae of the sarcoplasmic reticulum and the sarcolemma, peripheral couplings, were present. The electrophysiological implications of the absence of transverse tubules are discussed. The cisternae of the couplings showed periodic tubular extensions toward the sarcolemma. A regularly spaced array of Z line-like material was observed, suggesting a possible mechanism for sarcomere growth.

scholarly journals A Fixed Charge Model of the Transverse Tubular System of Frog Sartorius

1969 ◽  
Vol 54 (2) ◽  
pp. 178-187 ◽  
Author(s):  
Stanley I. Rapoport
Keyword(s):  
External Solution ◽  
Fixed Charge ◽  
Transverse Tubular System ◽  
Charge Model ◽  
Tubular System ◽  
Charge Concentration ◽  
Frog Sartorius ◽  
System Volume ◽  
Osmotic Pressure Difference ◽  
T System

Volume changes of the transverse tubular system (T system) of frog sartorius in different solutions can be explained by a model which assumes fixed negative charges in the T system lumen, an open T system mouth, and a Donnan equilibrium between the T system and external solution. The T system volume is regulated by the osmotic pressure difference between the lumen and external solution, as well as by constraining forces whose nature is as yet unclear. The decreased swelling tendency produced by hypotonic solutions and increased tendency produced by some hypertonic solutions are ascribed to changes in the pressure constraint from the sarcoplasm. Fixed charge concentration was estimated tentatively from swelling and resistivity data to be between 0.1 and 0.4 M.

scholarly journals Action Potentials, Afterpotentials, and Excitation-Contraction Coupling in Frog Sartorius Fibers without Transverse Tubules

1969 ◽  
Vol 53 (3) ◽  
pp. 298-310 ◽  
Author(s):  
Peter W. Gage ◽  
Robert S. Eisenberg
Keyword(s):  
Membrane Potential ◽  
Short Duration ◽  
Action Potentials ◽  
Sartorius Muscle ◽  
Transverse Tubules ◽  
Excitation Contraction Coupling ◽  
Transverse Tubular System ◽  
Contraction Coupling ◽  
Tubular System ◽  
Frog Sartorius

In frog sartorius muscle fibers in which the transverse tubular system has been disrupted by treatment with glycerol, action potentials which are unaccompanied by twitches can be recorded. These action potentials appear to be the same as those recorded in normal fibers except that the early afterpotential usually consists of a small hyperpolarization of short duration. After a train of action potentials no late afterpotential is seen even when the membrane potential is changed from the resting level. In fibers without transverse tubules hyperpolarizing currents do not produce a creep in potential. The interruption of excitation-contraction coupling, the changes in the afterpotentials, and the disappearance of creep are all attributed to the lack of a transverse tubular system.

Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

1977 ◽  
Vol 35 ◽  
pp. 570-571 ◽  
Author(s):  
Lee D. Peachey ◽  
Clara Franzini-Armstrong
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Three Dimensional ◽  
Biological Tissues ◽  
High Voltage Electron Microscopy ◽  
Transverse Tubular System ◽  
Peroxidase Reaction ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

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