Possible role of the transverse tubules in accumulating calcium released from the terminal cisternae by stimulation and drugs

1982 ◽  
Vol 60 (4) ◽  
pp. 503-507 ◽  
Author(s):  
C. P. Bianchi ◽  
S. Narayan
Keyword(s):  
Kinetic Analysis ◽  
Time Constant ◽  
Transverse Tubules ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Mechanical Threshold ◽  
A New Technique ◽  
Frog Sartorius ◽  
Terminal Cisternae

The sizes of the rapidly exchanging and slowly exchanging Ca2+ pools were estimated in frog sartorius muscles. A new technique using Sr2+ to extract the rapidly exchanging pool was used. The method avoids problems of kinetic analysis. The results showed that stimulation causes Ca2+ to be translocated from a compartment which exchanges with a time constant of 800 min to a compartment that can be washed out in 15 min. This is likely a transfer from the terminal cisternae to the transverse tubule. Calculations show that this would represent 0.9% of the Ca2+ released in each twitch. After 300 twitches produced by a 1-Hz stimulation, this accumulation could have increased the Ca concentration in the transverse tubules to 70 mM. A marked increase of Ca2+ concentration of this magnitude in the transverse tubules would raise the mechanical threshold for excitation–contraction coupling and would decrease the efficiency of coupling between contraction and excitation. This could be the explanation of the fatigue observed during this kind of stimulation.

scholarly journals THE SARCOPLASMIC RETICULUM AND TRANSVERSE TUBULES OF THE FROG'S SARTORIUS

1965 ◽  
Vol 25 (3) ◽  
pp. 209-231 ◽  
Author(s):  
Lee D. Peachey
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Surface Area ◽  
Osmium Tetroxide ◽  
Fiber Surface ◽  
Sartorius Muscle ◽  
Fiber Volume ◽  
Transverse Tubules ◽  
Contraction Coupling ◽  
Terminal Cisternae

The sarcoplasmic reticulum of the frog's sartorius muscle was examined by electron microscopy following sequential fixation in glutaraldehyde and osmium tetroxide and embedding in Epon. The earlier results of Porter and Palade on Ambystoma muscle were confirmed in the sartorius. In addition, the transverse tubules were observed to be continuous across the width of the fiber, a set of flat intermediate cisternae was seen to connect the terminal cisternae to the longitudinal tubules in the A band, and the continuous reticulum collar at the center of the A band was found to be perforated by circular and elongated pores (the fenestrated collar). The transverse tubules have a volume about 0.3 per cent of the fiber volume, and a surface area about 7 times the outer cylindrical surface area for a fiber 100 µ in diameter. The terminal cisternae, the intermediate cisternae, and the longitudinal tubules together with the fenestrated collar each have a volume of 4 to 5 per cent of the fiber volume and a surface area 40 to 50 times the outer surface area of a fiber 100 µ in diameter. Some evidence for continuity of the transverse tubules with the fiber surface is presented, but this is thought to be not so convincing as evidence presented by others. The results are discussed in terms of a possible mechanism for a role of the transverse tubules and sarcoplasmic reticulum in excitation-contraction coupling, as suggested by their morphology and a variety of physiological studies. In this scheme, the transverse tubules are thought to be electrically coupled to the terminal cisternae, so that depolarization of the fiber surface spreads inward along the transverse tubules and to the terminal cisternae, initiating the release of a contraction-activating substance.

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.

Extracellular divalent cations in excitation–contraction coupling: hypertonic solution effects

1982 ◽  
Vol 60 (4) ◽  
pp. 440-445
Author(s):  
Isao Oota ◽  
Isao Kosaka ◽  
Torao Nagai ◽  
Hideyo Yabu
Keyword(s):  
Skeletal Muscle ◽  
Divalent Cations ◽  
Muscle Fibers ◽  
Hypertonic Solution ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Skeletal Muscle Fibers ◽  
Membrane Bound

It is the purpose of this article to point out that the membrane-bound Ca plays an important role in excitation–contraction (E–C) coupling of skeletal muscle fibers and that other divalent cations are unable to substitute for this role of membrane-bound Ca.

Excitation-contraction coupling in HFpEF versus HFrEF: Role of transverse-axial tubule system

2020 ◽  
Vol 140 ◽  
pp. 46
Author(s):  
Xin Yue ◽  
Peter Kilfoil ◽  
Rui Zhang ◽  
Stephan Aynaszyan ◽  
Yushun Zhang ◽  
...  
Keyword(s):  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Transverse Axial
Sign in / Sign up

Export Citation Format

Share Document