Filament Lengths in Striated Muscle

Page, Sally; Huxley, H. E.

doi:10.1083/jcb.19.2.369

Cited by 323 publications

(218 citation statements)

References 10 publications

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“…R, which does not depend on the total concentration of troponin, represents the fraction of Ca-free sites that were available at rest that become complexed by Ca. The z axis extends to only 1,025 nm, which is half the length of thin filaments in frog muscle (Page and Huxley, 1963). It is clear from the figure that, in the steady state, almost all of the Ca that is bound to the Caregulatory sites on troponin lies within the region z ~< 500 nm.…”

Section: Application To Profiles Of A[ca] In An Idealized Myofibrilmentioning

confidence: 86%

Calcium release and its voltage dependence in frog cut muscle fibers equilibrated with 20 mM EGTA.

Pape

Jong

Chandler

1995

The Journal of General Physiology

129

295

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Sarcoplasmic reticulum (SR) Ca release was studied at 13-16~ in cut fibers (sarcomere length, 3.4-3.9 I~m) mounted in a double Vaseline-gap chamber. The amplitude and duration of the action-potential stimulated free [Ca] transient were reduced by equilibration with end-pool solutions that contained 20 mM EGTA with 1.76 mM Ca and 0.63 mM phenol red, a maneuver that appeared to markedly reduce the amount of Ca complexed by troponin. A theoretical analysis shows that, under these conditions, the increase in myoplasmic free [Ca] is expected to be restricted to within a few hundred nanometers of the SR Ca release sites and to have a time course that essentially matches that of release. Furthermore, almost all of the Ca that is released from the SR is expected to be rapidly bound by EGTA and exchanged for protons with a 1:2 stoichiometry. Consequently, the time course of SR Ca release can be estimated by scaling the ApH signal measured with phenol red by -13/2. The value of 13, the buffering power of myoplasm, was determined in fibers equilibrated with a combination of EGTA, phenol red, and fura-2; its mean value was 22 mM/pH unit. The Ca content of the SR (expressed as myoplasmic concentration) was estimated from the total amount of Ca released by either a train of action potentials or a depleting voltage step; its mean value was 2,685 I~M in the action-potential experiments and 2,544 IxM in the voltage-clamp experiments. An action potential released, on average, 0.14 of the SR Ca content with a peak rate of release of,'~5 %/ms. A second action potential, elicited 20 ms later, released only 0.6 times as much Ca (expressed as a fraction of the SR content), probably because Ca inactivation of Ca release was produced by the first action potential. During a depolarizing voltage step to 60 mV, the rate of Ca release rapidly increased to a peak value of~3 %/ms and then decreased to a quasi-steady level that was only 0.6 times as large; this decrease was also probably due to Ca inactivation of Ca release. SR Ca release was studied with small step depolarizations that open no more than one SR Ca channel in 7

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Section: Application To Profiles Of A[ca] In An Idealized Myofibrilmentioning

confidence: 86%

Calcium release and its voltage dependence in frog cut muscle fibers equilibrated with 20 mM EGTA.

Pape

Jong

Chandler

1995

The Journal of General Physiology

129

295

View full text Add to dashboard Cite

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“…Recent measurements of the diameter of thick filaments in similarly fixed flexor carpi radialis muscle of human and heart muscle of several species indicate that the diameter is about 120 A. In addition, Huxley (1963) observed a thick filament diameter of 120 A in rabbit psoas muscle fixed in formaldehyde and negatively stained. It should be noted, however, that thick-filament diameters of 150 A have been reported in a fish muscle (Franzini-Armstrong and Porter, 1964).…”

Section: Discussionmentioning

confidence: 99%

The Filament Lattice of Cockroach Thoracic Muscle

Hagopian

Spiro

1968

The Journal of Cell Biology

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The fine structure of the tergo-coxal muscle of the cockroach, Leucophaea maderae, has been studied with the electron microscope. This muscle differs from some other types of insect flight muscles inasmuch as the ratio of thin to thick filaments is 4 instead of the characteristic 3. The cockroach flight muscle also differs from the cockroach femoral muscle in thin to thick filament ratios and diameters and in lengths of thick filaments. A comparison of these latter three parameters in a number of vertebrate and invertebrate muscles suggests in general that the diameters and lengths of the thick filaments and thin to thick filament ratios are related.

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“…Based on these results we assumed an A-band length of 1 .60 ;Lm and used this value as an internal standard for all labeling measurements made directly from prints (15).…”

Section: Methodsmentioning

confidence: 99%

Localization of C-protein isoforms in chicken skeletal muscle: ultrastructural detection using monoclonal antibodies.

Dennis¹,

Shimizu²,

Reinach³

et al. 1984

The Journal of Cell Biology

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Monoclonal antibodies (McAbs) specific for the fast (MF-1) and slow (ALD-66) isoforms of C-protein from chicken skeletal muscle have been produced and characterized. Using these antibodies it was possible to demonstrate that skeletal muscles of varying fiber type express different isoforms of this protein and that in the posterior latissimus dorsi muscle both isoforms are co-expressed in the same myofiber (17, 18). Since we had shown that both isoforms were present in all sarcomeres, it was feasible to test whether the two isoforms co-distributed in the same 43-nm repeat within the A-band, thereby establishing a minimum number of C-proteins per repeat in the thick filaments. Here we describe the ultrastructural localization of C-protein in myofibers from three muscle types of the chicken using these same McAbs. We observed that although C-protein was present in a 43-nm repeat along the filaments in all three muscles, there were marked differences in the absolute number and position occupied by the different isoforms. Since McAbs MF-1 and ALD-66 decorated the same 43-nm repeats in the A-bands of the posterior latissimus dorsal muscle, we suggest that at least two C-proteins can co-localize at binding sites 43 nm apart along thick filaments of this muscle.

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Filament Lengths in Striated Muscle

Cited by 323 publications

References 10 publications

Calcium release and its voltage dependence in frog cut muscle fibers equilibrated with 20 mM EGTA.

Calcium release and its voltage dependence in frog cut muscle fibers equilibrated with 20 mM EGTA.

The Filament Lattice of Cockroach Thoracic Muscle

Localization of C-protein isoforms in chicken skeletal muscle: ultrastructural detection using monoclonal antibodies.

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