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 The Mode of Transverse Spread of Contraction Initiated by Local Activation in Single Frog Muscle Fibers

1967 ◽  
Vol 50 (9) ◽  
pp. 2167-2176 ◽  
Author(s):  
Haruo Sugi ◽  
Rikuo Ochi
Keyword(s):  
Muscle Fibers ◽  
Fiber Surface ◽  
Ringer Solution ◽  
Frog Muscle ◽  
Transverse Tubular System ◽  
Local Activation ◽  
Current Pulses ◽  
Negative Current ◽  
Tubular System

Isolated single frog muscle fibers were locally activated by applying negative current pulses to a pipette whose tip was in contact with the fiber surface. In contrast to the graded inward spread of contraction initiated by a moderate depolarization, the contraction in response to a strong negative current was observed to spread transversely around the whole perimeter but not through the center of the fiber. This response was elicited only with pipettes of more than 6 µ diameter. The response was still present if the sodium of the Ringer solution was replaced by choline, or the chloride was replaced by nitrate or propionate. The duration of the response appeared to be independent of the duration of stimulating current in fresh fibers, while the contraction lasted as long as the current went on in deteriorated fibers. The contraction was first initiated at the area of fiber surface covered by the pipette, and spread around the perimeter of the fiber with a velocity of 0.8–6 cm/sec. Possible mechanisms of the response are discussed in connection with the properties of the transverse tubular system, the possibility of some self-propagating process along the walls of the tubules being suggested.

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 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 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.

Sign in / Sign up

Export Citation Format

Share Document