scholarly journals CARDIAC MUSCLE

1968 ◽  
Vol 36 (3) ◽  
pp. 497-526 ◽  
Author(s):  
Joachim R. Sommer ◽  
Edward A. Johnson
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Guinea Pig ◽  
Cardiac Muscle ◽  
Extracellular Space ◽  
Light And Electron Microscopy ◽  
Rabbit Heart ◽  
Contraction Coupling ◽  
The Difference

With light and electron microscopy a comparison has been made of the morphology of ventricular (V) and Purkinje (P) fibers of the hearts of guinea pig, rabbit, cat, dog, goat, and sheep. The criteria, previously established for the rabbit heart, that V fibers are distinguished from P fibers by the respective presence and absence of transverse tubules is shown to be true for all animals studied. No evidence was found of a permanent connection between the sarcoplasmic reticulum and the extracellular space. The sarcoplasmic reticulum (SR) of V fibers formed couplings with the sarcolemma of a transverse tubule (interior coupling) and with the peripheral sarcolemma (peripheral coupling), whereas in P fibers the SR formed only peripheral couplings. The forms of the couplings were identical. The significance, with respect to excitation-contraction coupling, of the difference in the form of the couplings in cardiac versus skeletal muscle is discussed together with the electrophysiological implications of the differing geometries of bundles of P fibers from different animals.

scholarly journals Congenital myopathy associated with the triadin knockout syndrome

Neurology ◽  
2017 ◽  
Vol 88 (12) ◽  
pp. 1153-1156 ◽  
Author(s):  
Andrew G. Engel ◽  
Keeley R. Redhage ◽  
David J. Tester ◽  
Michael J. Ackerman ◽  
Duygu Selcen
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Light And Electron Microscopy ◽  
Deltoid Muscle ◽  
Congenital Myopathy ◽  
Compound Heterozygous

Objective:Triadin is a component of the calcium release complex of cardiac and skeletal muscle. Our objective was to analyze the skeletal muscle phenotype of the triadin knockout syndrome.Methods:We performed clinical evaluation, analyzed morphologic features by light and electron microscopy, and immunolocalized triadin in skeletal muscle.Results:A 6-year-old boy with lifelong muscle weakness had a triadin knockout syndrome caused by compound heterozygous null mutations in triadin. Light microscopy of a deltoid muscle specimen shows multiple small abnormal spaces in all muscle fibers. Triadin immunoreactivity is absent from type 1 fibers and barely detectable in type 2 fibers. Electron microscopy reveals focally distributed dilation and degeneration of the lateral cisterns of the sarcoplasmic reticulum and loss of the triadin anchors from the preserved lateral cisterns.Conclusions:Absence of triadin in humans can result in a congenital myopathy associated with profound pathologic alterations in components of the sarcoplasmic reticulum. Why only some triadin-deficient patients develop a skeletal muscle phenotype remains an unsolved question.

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.

Neuromuscular junction alterations in extraocular muscles of myotonic rats

1983 ◽  
Vol 41 ◽  
pp. 654-655
Author(s):  
Bruce R. Pachter ◽  
Arthur Eberstein
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Neuromuscular Junction ◽  
High Frequency ◽  
Light And Electron Microscopy ◽  
Extraocular Muscles ◽  
Dense Bodies ◽  
Myofibrillar Degeneration ◽  
Cell Vacuolization

Rats treated with 20,25-diazacholesterol manifest clinical as well as physiological signs characteristic of human myotonic dystrophy. The extraocular muscles (EOMs) of such myotonic rats were shewn in a prior study to exhibit by electromyography, prolonged insertion activity, high frequency bizzare discharges, and myotonic responses, which are comparable to that observed in skeletal muscle. Light and electron microscopy of the EOMs revealed numerous fiber alterations, i.e., dense bodies, atrophic and angulated fibers, cell vacuolization, dilation and proliferation of the sarcoplasmic reticulum, mu11ilamllar membranous bodies, atypical mitochondrial clusters and disruptions, mitochondrial inclusions, excessive lipid accumulations, and myofibrillar degeneration. Many of these changes have been reported in human myotonic peripheral musculature. The most susceptible fiber populations in the EOMs were found to be the pale, intermediate, and red singly-innervated fibers of the global region; the pale fibers were the most affected.

scholarly journals STRUCTURE OF THE LONGITUDINAL BODY MUSCLES OF AMPHIOXUS

1961 ◽  
Vol 10 (4) ◽  
pp. 159-176 ◽  
Author(s):  
Lee D. Peachey
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Sarcoplasmic Reticulum ◽  
Internal Structure ◽  
Striated Muscle ◽  
Light And Electron Microscopy ◽  
Maximum Distance ◽  
Hexagonal Array ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling

The structure of the longitudinal body muscles of Branchiostoma caribaeum has been studied by light and electron microscopy. These muscles are shown to be composed of fibers in the form of flat lamellae about 0.8µ in thickness, more than 100 µ wide, and reaching in length from one intermuscular septum to the next, a distance of about 0.6 mm. Each flat fiber is covered by a plasma membrane and contains a single myofibril consisting of myofilaments packed in the interdigitating hexagonal array characteristic of vertebrate striated muscle. Little or no sarcoplasmic reticulum is present. Mitochondria are found infrequently and have a tubular internal structure. These morphological observations are discussed in relation to a proposed hypothesis of excitation-contraction coupling. It is pointed out that the maximum distance from surface to myofilament in these muscles is about 0.5 µ and that diffusion of an "activating" substance over this distance would essentially be complete in less than 0.5 msec. after its release from the plasma membrane. It is concluded that the flat form of amphioxus muscle substitutes for the specialized mechanisms of excitation-contraction coupling thought possibly to involve the sarcoplasmic reticulum in higher vertebrate muscles.

Interaction of Bupivacaine and Tetracaine with the Sarcoplasmic Reticulum Ca2+Release Channel of Skeletal and Cardiac Muscles 

1999 ◽  
Vol 90 (3) ◽  
pp. 835-843 ◽  
Author(s):  
Hirochika Komai ◽  
Andrew J. Lokuta
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Ryanodine Receptor ◽  
Local Anesthetic ◽  
Local Anesthetics ◽  
Specific Effect ◽  
Receptor Activity ◽  
Maximal Inhibition ◽  
Release Channel

Background Although various local anesthetics can cause histologic damage to skeletal muscle when injected intramuscularly, bupivacaine appears to have an exceptionally high rate of myotoxicity. Research has suggested that an effect of bupivacaine on sarcoplasmic reticulum Ca2+ release is involved in its myotoxicity, but direct evidence is lacking. Furthermore, it is not known whether the toxicity depends on the unique chemical characteristics of bupivacaine and whether the toxicity is found only in skeletal muscle. Methods The authors studied the effects of bupivacaine and the similarly lipid-soluble local anesthetic, tetracaine, on the Ca2+ release channel-ryanodine receptor of sarcoplasmic reticulum in swine skeletal and cardiac muscle. [3H]Ryanodine binding was used to measure the activity of the Ca2+ release channel-ryanodine receptors in microsomes of both muscles. Results Bupivacaine enhanced (by two times at 5 mM) and inhibited (66% inhibition at 10 mM) [3H]ryanodine binding to skeletal muscle microsomes. In contrast, only inhibitory effects were observed with cardiac microsomes (about 3 mM for half-maximal inhibition). Tetracaine, which inhibits [3H]ryanodine binding to skeletal muscle microsomes, also inhibited [3H]ryanodine binding to cardiac muscle microsomes (half-maximal inhibition at 99 microM). Conclusions Bupivacaine's ability to enhance Ca2+ release channel-ryanodine receptor activity of skeletal muscle sarcoplasmic reticulum most likely contributes to the myotoxicity of this local anesthetic. Thus, the pronounced myotoxicity of bupivacaine may be the result of this specific effect on Ca2+ release channel-ryanodine receptor superimposed on a nonspecific action on lipid bilayers to increase the Ca2+ permeability of sarcoplasmic reticulum membranes, an effect shared by all local anesthetics. The specific action of tetracaine to inhibit Ca2+ release channel-ryanodine receptor activity may in part counterbalance the nonspecific action, resulting in moderate myotoxicity.

scholarly journals Calcium Exchange and Contraction Strength of Guinea Pig Atrium in Normal and Hypertonic Media

1969 ◽  
Vol 54 (4) ◽  
pp. 494-511 ◽  
Author(s):  
Gerald R. Little ◽  
William W. Sleator
Keyword(s):  
Steady State ◽  
Ion Exchange ◽  
Guinea Pig ◽  
Extracellular Space ◽  
Entry Rate ◽  
Steady State Condition ◽  
Peak Tension ◽  
Guinea Pig Atrium ◽  
Calcium Exchange ◽  
The Difference

A Krebs-Henseleit (KH) medium made hypertonic by adding nonpermeant molecules substantially increased the isometric peak tension at steady-state contractions below 3 per sec in guinea pig atrium at 27°C. Action potential durations were decreased. KH plus 100 mM raffinose or sucrose resulted in similar and nearly maximal changes which were essentially reversible upon return to normal KH. When one active contracting atrium was used to passively stretch a second atrium, the difference in Ca ion exchange (1 min exchange with the extracellular space) between active and stretched atria significantly increased at 1 per sec and at 2 per sec in going from normal to 100 mM hypertonic KH. The calculated mean Ca ion cellular exchange per beat per 100 g of cells (a) doubled in changing from normal to 100 mM hypertonic KH, and (b) decreased slightly in changing from contractions of 1 per sec to 2 per sec in normal KH. These data are consistent with the hypothesis (a) that Ca ion entry per beat from the extracellular space is proportional to membrane depolarized time with a constant medium and a steady-state condition, and the hypothesis (b) that 100 mM hypertonicity doubles the Ca ion entry rate during depolarization. These data enable rejection of the hypothesis that the peak tension is proportional to the Ca ion entry per beat from the extracellular space under steady-state conditions, and suggest that any additional Ca ion involved in the larger contractions at higher frequencies comes from an increase in Ca ion available from intracellular stores.

Inverse alterations of BCKA dehydrogenase activity in cardiac and skeletal muscles of diabetic rats

1999 ◽  
Vol 277 (4) ◽  
pp. E685-E692 ◽  
Author(s):  
Yolanda B. Lombardo ◽  
Cynthia Serdikoff ◽  
Manikkavasagar Thamotharan ◽  
Harbhajan S. Paul ◽  
Siamak A. Adibi
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Protein Expression ◽  
Cardiac Muscle ◽  
Dehydrogenase Activity ◽  
Skeletal Muscles ◽  
Diabetic Rats ◽  
Gene Expressions ◽  
The Difference ◽  
Activity State

Rat cardiac and skeletal muscles, which have been used as model tissues for studies of regulation of branched-chain α-keto acid (BCKA) oxidation, vary greatly in the activity state of their BCKA dehydrogenase. In the present experiment, we have investigated whether they also vary in response of their BCKA dehydrogenase to a metabolic alteration such as diabetes and, if so, to investigate the mechanism that underlies the difference. Diabetes was produced by depriving streptozotocin-treated rats of insulin administration for 96 h. The investigation of BCKA dehydrogenase in the skeletal muscle (gastrocnemius) showed that diabetes 1) increased its activity, 2) increased the protein and gene expressions of all of its subunits (E1α, E1β, E2), 3) increased its activity state, 4) decreased the rate of its inactivation, and 5) decreased the protein expression of its associated kinase (BCKAD kinase) without affecting its gene expression. In sharp contrast, the investigation of BCKA dehydrogenase in the cardiac muscle showed that diabetes 1) decreased its activity, 2) had no effect on either protein or gene expression of any of its subunits, 3) decreased its activity state, 4) increased its rate of inactivation, and 5) increased both the protein and gene expressions of its associated kinase. In conclusion, our data suggest that, in diabetes, the protein expression of BCKAD kinase is downregulated posttranscriptionally in the skeletal muscle, whereas it is upregulated pretranslationally in the cardiac muscle, causing inverse alterations of BCKA dehydrogenase activity in these muscles.

Lactate inhibits Ca2+-activated Ca2+-channel activity from skeletal muscle sarcoplasmic reticulum

1997 ◽  
Vol 82 (2) ◽  
pp. 447-452 ◽  
Author(s):  
Terence G. Favero ◽  
, Anthony C. Zable ◽  
, David Colter ◽  
Jonathan J. Abramson
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Single Channel ◽  
Channel Activity ◽  
Release Channel ◽  
Muscle Lactate ◽  
Tension Development ◽  
Contraction Coupling ◽  
Single Channel Activity ◽  
High Concentrations

Favero, Terence G., Anthony C. Zable, David Colter, and Jonathan J. Abramson. Lactate inhibits Ca2+-activated Ca2+-channel activity from skeletal muscle sarcoplasmic reticulum. J. Appl. Physiol. 82(2): 447–452, 1997.—Sarcoplasmic reticulum (SR) Ca2+-release channel function is modified by ligands that are generated during about of exercise. We have examined the effects of lactate on Ca2+- and caffeine-stimulated Ca2+ release, [3H]ryanodine binding, and single Ca2+-release channel activity of SR isolated from rabbit white skeletal muscle. Lactate, at concentrations from 10 to 30 mM, inhibited Ca2+- and caffeine-stimulated [3H]ryanodine binding to and inhibited Ca2+- and caffeine-stimulated Ca2+ release from SR vesicles. Lactate also inhibited caffeine activation of single-channel activity in bilayer reconstitution experiments. These findings suggest that intense muscle activity, which generates high concentrations of lactate, will disrupt excitation-contraction coupling. This may lead to decreases in Ca2+ transients promoting a decline in tension development and contribute to muscle fatigue.

Some Effects of Caffeine and Quinidine on Sarcoplasmic Reticulum of Skeletal and Cardiac Muscle

1973 ◽  
Vol 51 (7) ◽  
pp. 499-503 ◽  
Author(s):  
William R. Thorpe
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Myocardial Contractility ◽  
Gastrocnemius Muscle ◽  
Negative Inotropic Effect ◽  
Inotropic Effect ◽  
Experimental Conditions

Sarcoplasmic reticulum (SR) was prepared from the gastrocnemius muscle and the heart of freshly killed rabbits. It was found that the skeletal SR actively bound significantly more calcium than did the cardiac SR under the same experimental conditions. The effect of caffeine and quinidine on the release of calcium actively bound by both cardiac and skeletal SR was studied. Quinidine (10−3 M) released 4.1% of the calcium bound by skeletal SR and 27.7% of that bound by cardiac SR. Similarly, caffeine (20 mM) released 10.5% and 34.3% of the calcium bound by skeletal and cardiac SR, respectively. It is suggested that both caffeine and quinidine could produce contracture of skeletal muscle by acting on the SR and that caffeine could stimulate myocardial contractility through its action on the cardiac SR. However, it is unlikely that quinidine exerts its negative inotropic effect on the heart through its calcium releasing action on the cardiac SR.

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