scholarly journals THE FINE STRUCTURE OF FAST AND SLOW CRUSTACEAN MUSCLES

1967 ◽  
Vol 35 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Wolf H. Fahrenbach
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Sarcomere Length ◽  
Morphological Type ◽  
Slow Muscle ◽  
Anatomical Location ◽  
Hexagonal Array ◽  
Cancer Magister ◽  
Thin Filaments ◽  
Cypridopsis Vidua ◽  
Postural Muscles

Known phasic and tonic muscle fibers of the crab Cancer magister were studied by electron microscopy. Phasic fibers have sarcomeres about 4.5 µ long, small polygonal myofibrils, and a well-developed sarcoplasmic reticulum. The thick myofilaments, disposed in hexagonal array, are each surrounded by six thin filaments. The tonic fibers have a sarcomere length of about 12 µ, larger myofibrils, a poorly developed sarcoplasmic reticulum, and a disorderly array of myofilaments. Each thick myofilament is surrounded by 10–12 thin filaments. The same morphological type of slow muscle has been found in the crustaceans, Macrocyclops albidus, Cypridopsis vidua, and Balanus cariosus, in each case in an anatomical location consistent with tonic action. A search of the literature indicates that this type of muscle is found in all classes of arthropods and is confined to visceral and postural muscles or specializations of these.

scholarly journals ELECTROMECHANICAL COUPLING IN TUBULAR MUSCLE FIBERS

1972 ◽  
Vol 52 (3) ◽  
pp. 626-638 ◽  
Author(s):  
Arieh Gilai ◽  
I. Parnas
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cell Membrane ◽  
Electromechanical Coupling ◽  
Surface Membrane ◽  
Hexagonal Array ◽  
Thin Filaments ◽  
Transverse Tubular System ◽  
The Core ◽  
Tubular System ◽  
Terminal Cisternae

The tubular fibers of the claw-closer muscle of the scorpion have a central core containing nuclei and mitochondria. The myofibrils have the shape of thin lamellae (1 µ) extending radially from the core to the surface membrane (20 µ). The thick myofilaments are organized in a hexagonal array with orbits of 10–13 thin myofilaments. The ratio of thick-to-thin filaments is 1:5. Transverse tubular system (TS) openings are located between lamellated myofibrils. In each sarcomere two TS's are found, one on each side of the H band. The TS is composed of a transverse tubule and tubular pockets (TP). The TP's form diadic contact with the terminal cisternae of the sarcoplasmic reticulum. The TS can be traced from the cell membrane down to the cell core. The surface area of the TS was calculated to be six times that of the outer surface membrane.

Abstract 13820: Diastolic Dysfunction is Not Associated With Increased Diastolic Calcium During Experimental Uremic Cardiomyopathy

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Pamela D Winterberg ◽  
Rong Jiang ◽  
Bo Wang ◽  
Sonal Harbaran ◽  
Mary B Wagner
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Left Ventricular Hypertrophy ◽  
Diastolic Dysfunction ◽  
Ventricular Hypertrophy ◽  
Sarcomere Length ◽  
Treatment Options ◽  
Strain Analysis ◽  
Left Ventricular ◽  
Uremic Cardiomyopathy ◽  
Underlying Mechanisms

Introduction: The underlying mechanisms contributing to uremic cardiomyopathy during chronic kidney disease (CKD) are poorly understood, limiting treatment options. Hypothesis: We aimed to determine if altered calcium (Ca2+) handling in cardiomyocytes contributes to diastolic dysfunction in a mouse model of CKD. Methods: CKD was induced in male 129X1/SvJ mice through five-sixths nephrectomy in a two-stage surgery. Age-matched mice served as controls. Transthoracic echocardiography and speckle-tracking based strain analysis (Vevo2100, VisualSonics, Toronto, Canada) were performed at 8 weeks post-CKD (n=7-8) to assess heart structure and function. Cardiomyocytes isolated from mice with or without CKD (n=3 mice per group, 10-12 cells/mouse) were loaded with Fura 2-AM, paced by field stimulation (1 Hz), and imaged with a dual-excitation fluorescence photomultiplier system (IonOptix Inc, Milton, MA) to measure Ca2+ transients and sarcomere length. Sarcoplasmic reticulum Ca2+ content was determined following rapid application of caffeine.[[Unable to Display Character: &#8232;]] Results: CKD mice displayed left ventricular hypertrophy (LVAW;d 1.46 ± 0.134 vs 1.04 ± 0.129 mm; p<0.001) and decreased longitudinal strain (19 ± 4.1% vs 30 ± 2.3%; p<0.0001) compared to control mice. Resting sarcomere length was significantly shorter in cardiomyocytes isolated from CKD mice compared to normal mice (1.86 ± 0.054 vs 1.89 ± 0.047 nm; p = 0.016), but relaxation time was unchanged (0.21 ± 0.12 vs 0.21 ± 0.15 seconds, p=0.4). Unexpectedly, the baseline cytosolic Ca2+ content was lower in uremic myocytes (1.22 ± 0.353 vs 1.46 ± 0.252 AU, p=0.002). However, the Ca2+ transient amplitude (0.39 ± 0.177 vs 0.41 ± 0.167 AU, p=0.4) and sarcoplasmic reticulum Ca2+ content (1.15 ± 0.321 vs 1.24 ± 0.550 AU, p=0.4) were comparable between CKD and normal cardiomyocytes.[[Unable to Display Character: &#8232;]] Conclusions: Mice with CKD have signs of left ventricular hypertrophy and diastolic dysfunction on echocardiography. Cardiomyocytes isolated from mice with CKD have shorter diastolic sarcomere length implying impaired relaxation, yet paradoxically have decreased diastolic calcium. Thus Ca2+ accumulation during diastole does not appear to contribute to impaired relaxation in this model.

scholarly journals Feeding wet distillers grains plus solubles contributes to sarcoplasmic reticulum membrane instability

2018 ◽  
Vol 58 (12) ◽  
pp. 2215 ◽  
Author(s):  
M. D. Chao ◽  
K. I. Domenech-Perez ◽  
L. S. Senaratne-Lenagala ◽  
C. R. Calkins
Keyword(s):  
Fatty Acid ◽  
Sarcoplasmic Reticulum ◽  
Lipid Oxidation ◽  
Neutral Lipid ◽  
Sarcomere Length ◽  
Membrane Integrity ◽  
Distillers Grains ◽  
Free Calcium ◽  
Post Mortem ◽  
Wet Distillers Grains

Feeding wet distillers grains plus solubles (WDGS) increases polyunsaturated fatty acid (PUFA) levels in beef. It was hypothesised that WDGS in feedlot diets increases PUFA concentration in the sarcoplasmic reticulum (SR) membrane, thereby altering membrane integrity, resulting in more rapid intracellular calcium leakage and improved tenderness. The objective of this study was to evaluate this hypothesis. Ninety-six crossbred steers were fed either a corn-based diet with 0% WDGS or 50% WDGS. Fifteen strip loins per treatment were collected, fabricated into steaks, aged and placed under retail display conditions. Steaks were used to measure tenderness, proteolysis, free calcium concentrations, lipid oxidation, sarcomere length and SR membrane fatty acid, phospholipid lipid, neutral lipid and total lipid profiles. Compared with steaks from steers fed 0% WDGS, steaks from steers fed 50% WDGS were more tender (P < 0.05) and had greater (P < 0.05) free calcium concentrations early post-mortem. Feeding 50% WDGS also tended to increase (P < 0.10) total PUFA concentrations, decrease (P < 0.10) total phospholipid concentration and increase (P < 0.10) total neutral lipid concentration for SR membrane. Steaks from steers fed 0% WDGS had greater (P < 0.05) lipid oxidation (TBARS values) than steaks from steers fed 50% WDGS after extended aging. Although differences in tenderness between the two treatments were detected, there were no corresponding differences (P > 0.10) in sarcomere length or proteolysis. This study showed that feeding WDGS may increase tenderness, possibly by increasing free calcium in muscle early post-mortem. However, the true mechanism that contributes to these differences is still unclear.

scholarly journals Biochemical heterogeneity of skeletal-muscle microsomal membranes. Membrane origin, membrane specificity and fibre types

1982 ◽  
Vol 202 (2) ◽  
pp. 289-301 ◽  
Author(s):  
Giovanni Salviati ◽  
Pompeo Volpe ◽  
Sergio Salvatori ◽  
Romeo Betto ◽  
Ernesto Damiani ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Total Phospholipid ◽  
Polyacrylamide Gel Electrophoresis ◽  
Freeze Fracture ◽  
Sucrose Density Gradient ◽  
Average Density ◽  
Slow Muscle ◽  
Fast And Slow Muscle ◽  
Dependent Atpase

1. Microsomes were isolated from rabbit fast-twitch and slow-twitch muscle and were separated into heavy and light fractions by centrifugation in a linear (0.3–2m) sucrose density gradient. The membrane origin of microsomal vesicles was investigated by studying biochemical markers of the sarcoplasmic-reticulum membranes and of surface and T-tubular membranes, as well as their freeze-fracture properties. 2. Polyacrylamide-gel electrophoresis showed differences in the Ca2+-dependent ATPase/calsequestrin ratio between heavy and light fractions, which were apparently consistent with their respective origin from cisternal and longitudinal sarcoplasmic reticulum, as well as unrelated differences, such as peptides specific to slow-muscle microsomes (mol.wts. 76000, 60000, 56000 and 45000). 3. Freeze-fracture electron microscopy of muscle microsomes demonstrated that vesicles truly derived from the sarcoplasmic reticulum, with an average density of 9nm particles on the concave face of about 3000/μm2 for both fast and slow muscle, were admixed with vesicles with particle densities below 1000/μm2. 4. As determined in the light fractions, the sarcoplasmic-reticulum vesicles accounted for 84% and 57% of the total number of microsomal vesicles, for fast and slow muscle respectively. These values agreed closely with the percentage values of Ca2+-dependent ATPase protein obtained by gel densitometry. 5. The T-tubular origin of vesicles with a smooth concave fracture face in slow-muscle microsomes is supported by their relative high content in total phospholipid and cholesterol, compared with the microsomes of fast muscle, and by other correlative data, such as the presence of (Na++K+)-dependent ATPase activity and of low amounts of Na+-dependent membrane phosphorylation. 6. Among intrinsic sarcoplasmic-reticulum membrane proteins, a proteolipid of mol.wt. 12000 is shown to be identical in the microsomes of both fast and slow muscle and the Ca2+-dependent ATPase to be antigenically and catalytically different, though electrophoretically homogeneous. 7. Basal Mg2+-activated ATPase activity was found to be high in light microsomes from slow muscle, but its identification with an enzyme different from the Ca2+-dependent ATPase is still not conclusive. 8. Enzyme proteins that are suggested to be specific to slow-muscle longitudinal sarcoplasmic reticulum are the flavoprotėin NADH:cytochrome b5 reductase (mol.wt. 32000), cytochrome b5 (mol.wt. 17000) and the stearoyl-CoA desaturase, though essentially by criteria of plausibility.

scholarly journals Differences in the Charge Distribution of Glycerol-Extracted Muscle Fibers in Rigor, Relaxation, and Contraction

1974 ◽  
Vol 64 (5) ◽  
pp. 551-567 ◽  
Author(s):  
Suzanne M. Pemrick ◽  
Charles Edwards
Keyword(s):  
Charge Distribution ◽  
Sarcomere Length ◽  
Muscle Fibers ◽  
Psoas Muscle ◽  
Nonlinear Relationship ◽  
Thin Filaments ◽  
Rabbit Psoas ◽  
Relaxation Solution ◽  
The Difference ◽  
Rest Length

Glycerol-extracted rabbit psoas muscle fibers were impaled with KCl-filled glass microelectrodes. For fibers at rest-length, the potentials were significantly more negative in solutions producing relaxation than in solutions producing either rigor or contraction; further the potentials in the latter two cases were not significantly different. For stretched fibers, with no overlap between thick and thin filaments, the potentials did not differ in the rigor, the relaxation, or the contraction solutions. The potentials measured from fibers in rigor did not vary significantly with the sarcomere length. For relaxed fibers, however, the potential magnitude decreased with increasing sarcomere length. The difference between the potentials measured for rigor and relaxed fibers exhibited a nonlinear relationship with sarcomere length. The potentials from calcium-insensitive fibers were less negative in both the rigor and the relaxation solutions than those from normal fibers. When calcium-insensitive fibers had been incubated in Hasselbach and Schneider's solution plus MgCl2 or Guba-Straub's solution plus MgATP the potentials recorded upon impalement were similar in the rigor and the relaxation solution to those obtained from normal fibers in the relaxed state. It is concluded that the increase in the negative potential as the glycerinated fiber goes from rigor to relaxation may be due to an alteration in the conformation of the contractile proteins in the relaxed state.

scholarly journals Polarization of Tryptophan Fluorescence from Single Striated Muscle Fibers

1972 ◽  
Vol 59 (1) ◽  
pp. 103-120 ◽  
Author(s):  
C. G. dos Remedios ◽  
R. G. C. Millikan ◽  
M. F. Morales
Keyword(s):  
Sarcomere Length ◽  
Striated Muscle ◽  
Muscle Fibers ◽  
Tryptophan Fluorescence ◽  
Thin Filaments ◽  
A Value ◽  
Striated Muscle Fibers ◽  
Types Of Muscle Fibers ◽  
Cross Bridges ◽  
Contraction And Relaxation

Instrumentation has been developed to detect rapidly the polarization of tryptophan fluorescence from single muscle fibers in rigor, relaxation, and contraction. The polarization parameter (P⊥) obtained by exiciting the muscle tryptophans with light polarized perpendicular to the long axis of the muscle fiber had a magnitude P⊥ (relaxation) &gt; P⊥ (contraction) &gt; P⊥ (rigor) for the three types of muscle fibers examined (glycerinated rabbit psoas, glycerinated dorsal longitudinal flight muscle of Lethocerus americanus, and live semitendinosus of Rana pipiens). P⊥ from single psoas fibers in rigor was found to increase as the sarcomere length increased but in relaxed fibers P⊥ was independent of sarcomere length. After rigor, pyrophosphate produced little or no change in P⊥, but following an adenosine triphosphate (ATP)-containing solution, pyrophosphate produced a value of P⊥ that fell between the contraction and relaxation values. Sinusoidal or square wave oscillations of the muscle of amplitude 0.5–2.0% of the sarcomere length and frequency 1, 2, or 5 Hz were applied in rigor when the myosin cross-bridges are considered to be firmly attached to the thin filaments. No significant changes in P⊥ were observed in either rigor or relaxation. The preceding results together with our present knowledge of tryptophan distribution in the contractile proteins has led us to the conclusion that the parameter P⊥ is a probe of the contractile state of myosin which is probably sensitive to the orientation of the myosin S1 subfragment.

scholarly journals Polymorphism of sarcoplasmic-reticulum adenosine triphosphatase of rabbit skeletal muscle

1981 ◽  
Vol 197 (1) ◽  
pp. 245-248 ◽  
Author(s):  
E Damiani ◽  
R Betto ◽  
S Salvatori ◽  
P Volpe ◽  
G Salviati ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Immunosorbent Assay ◽  
Adenosine Triphosphatase ◽  
Slow Muscle ◽  
Fast Muscle ◽  
Enzyme Linked Immunosorbent Assay ◽  
Immunological Relationship ◽  
One Step ◽  
Membrane Bound

Antibody was raised in chickens against purified sarcoplasmic-reticulum Ca2+-activated ATPase (Ca2+-ATPase). The immunological relationship between the Ca2+-ATPase of fast-muscle and slow-muscle sarcoplasmic reticulum was investigated by a one-step and a two-step competitive enzyme-linked immunosorbent assay (ELISA). The results show marked antigenic differences between the membrane-bound Ca2+-ATPase of the sarcoplasmic-reticulum vesicles from fast muscle and slow muscle, beside differences in the membrane content of ATPase protein.

scholarly journals A proposed role for non-junctional transverse tubules in skeletal muscle as flexible segments allowing expansion of the transverse network

2019 ◽  
Vol 29 (2) ◽  
Author(s):  
Manuela Lavorato ◽  
Ramesh Iyer ◽  
Clara Franzini-Armstrong
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Skeletal Muscles ◽  
Sarcomere Length ◽  
Muscle Fibers ◽  
Entire Length ◽  
Small Fish ◽  
Transverse Tubules ◽  
T Tubules

Using a variety of technical approaches, we have detected the presence of continuous triads that cover the entire length of T tubules in the main white body muscles of several small fish. This is in contrast to the discontinuous association of sarcoplasmic reticulum with T tubules in the red muscles from the same fish as well as in all other previously described muscles in a large variety of skeletal muscles. We suggest that continuous triads are permissible only in muscle fibers that are not normally subject to significant changes in sarcomere length during normal in vivo activity, as is the case for white muscles in the trunk of fish.

Band Patterns in Chick Muscle at Short Sarcomere Length

1970 ◽  
Vol 28 ◽  
pp. 144-145
Author(s):  
M. Hagopian ◽  
D. Spiro ◽  
P. Yau
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Sarcomere Length ◽  
Pectoral Muscle ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Contraction Band

Glycerinated chick pectoral muscle was prepared for electron microscopy. Sarcomere lengths varied from 2.3 to 1.1μ reflecting various degrees of shortening. Over a sarcomere range of 2.3 to 1.3μ the thin actin filaments which measure 1.0μ and the thick myosin filaments which measure 1.5μ are constant in length (Fig. 1). At sarcomere lengths below 2μ the thin filaments penetrate through the center of the A band into the opposite halves of the sarcomere producing A contraction bands as previously described. In sarcomeres which measure 1.5 to 1.3μ additional contraction bands are noted adjacent to the Z lines. In longitudinal sections the array of filaments in the Z contraction band appears orderly (Fig. 2). It is our impression that these Z contraction bands result from penetration of the tapered lateral ends of the myosin filaments through the Z lines into the adjacent sarcomere rather than a crumpling of thick filaments as has been previously stated. Below 1.3μ in length the sarcomeres are disorganized, and it is not possible to define filament lengths.

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