scholarly journals Phosphate Starvation and the Nonlinear Dynamics of Insect Fibrillar Flight Muscle

1972 ◽  
Vol 60 (3) ◽  
pp. 307-336 ◽  
Author(s):  
D. G. S. White ◽  
John Thorson
Keyword(s):  
Nonlinear Dynamics ◽  
Adenosine Triphosphate ◽  
Rate Constants ◽  
Flight Muscle ◽  
Phosphate Starvation ◽  
Adenosine Diphosphate ◽  
Cross Bridge ◽  
Nonlinear Mechanical ◽  
Cross Bridges ◽  
Mechanical Dynamics

The nonlinear mechanical dynamics of glycerinated insect fibrillar flight muscle are investigated. The most striking nonlinearity reported previously, which often resulted in oscillatory work being limited to frequencies below those of natural flight, disappears if 5 mM or more orthophosphate is added to the experimental solutions. We show that two further asymmetric nonlinearities, which remain even though phosphate is present, are predicted by cross-bridge theory if one takes account of the expected distortion of attached cross-bridges as filament sliding becomes appreciable. Adenosine triphosphate and adenosine diphosphate have opponent effects upon the mechanical rate constants, suggesting a scheme for the sequential ordering of the events comprising the cross-bridge cycle.

Cross-bridge phosphorylation and regulation of latch state in smooth muscle

1988 ◽  
Vol 254 (1) ◽  
pp. C99-C106 ◽  
Author(s):  
C. M. Hai ◽  
R. A. Murphy
Keyword(s):  
Smooth Muscle ◽  
Steady State ◽  
Experimental Observation ◽  
Rate Constants ◽  
Regulatory Mechanism ◽  
Myosin Phosphorylation ◽  
Model Simulations ◽  
Cross Bridge ◽  
Cross Bridges ◽  
Latch State

We have developed a minimum kinetic model for cross-bridge interactions with the thin filament in smooth muscle. The model hypothesizes two types of cross-bridge interactions: 1) cycling phosphorylated cross bridges and 2) noncycling dephosphorylated cross bridges ("latch bridges"). The major assumptions are that 1) Ca2+-dependent myosin phosphorylation is the only postulated regulatory mechanism, 2) each myosin head acts independently, and 3) latch bridges are formed by dephosphorylation of an attached cross bridge. Rate constants were resolved by fitting data on the time courses of myosin phosphorylation and stress development. Comparison of the rate constants indicates that latch-bridge detachment is the rate-limiting step. Model simulations predicted a hyperbolic dependence of steady-state stress on myosin phosphorylation, which corresponded with the experimental observation of high values of stress with low levels of phosphorylation in intact tissues. Model simulations also predicted the experimental observation that an initial phosphorylation transient only accelerates stress development, with no effect on the final steady-state levels of stress. Because the only Ca2+-dependent regulatory mechanism in this model was activation of myosin light chain kinase, these results are consistent with the hypothesis that myosin phosphorylation is both necessary and sufficient for the development of the latch state.

scholarly journals Mechanical transients initiated by photolysis of caged ATP within fibers of insect fibrillar flight muscle.

1991 ◽  
Vol 98 (4) ◽  
pp. 657-679 ◽  
Author(s):  
M Yamakawa ◽  
Y E Goldman
Keyword(s):  
Rate Constant ◽  
Time Course ◽  
Flight Muscle ◽  
Order Rate Constant ◽  
Stretch Activation ◽  
Pulse Photolysis ◽  
Caged Atp ◽  
Cross Bridge ◽  
The Cross ◽  
Cross Bridges

Kinetics of the cross-bridge cycle in insect fibrillar flight muscle have been measured using laser pulse photolysis of caged ATP and caged inorganic phosphate (Pi) to produce rapid step increases in the concentration of ATP and Pi within single glycerol-extracted fibers. Rapid photochemical liberation of 100 microM-1 mM ATP from caged ATP within a fiber caused relaxation in the absence of Ca2+ and initiated an active contraction in the presence of approximately 30 microM Ca2+. The apparent second order rate constant for detachment of rigor cross-bridges by ATP was between 5 x 10(4) and 2 x 10(5) M-1s-1. This rate is not appreciably sensitive to the Ca2+ or Pi concentrations or to rigor tension level. The value is within an order of magnitude of the analogous reaction rate constant measured with isolated actin and insect myosin subfragment-1 (1986. J. Muscle Res. Cell Motil. 7:179-192). In both the absence and presence of Ca2+ insect fibers showed evidence of transient cross-bridge reattachment after ATP-induced detachment from rigor, as found in corresponding experiments on rabbit psoas fibers. However, in contrast to results with rabbit fibers, tension traces of insect fibers starting at different rigor tensions did not converge to a common time course until late in the transients. This result suggests that the proportion of myosin cross-bridges that can reattach into force-generating states depends on stress or strain in the filament lattice. A steady 10-mM concentration of Pi markedly decreased the transient reattachment phase after caged ATP photolysis. Pi also decreased the amplitude of stretch activation after step stretches applied in the presence of Ca2+ and ATP. Photolysis of caged Pi during stretch activation abruptly terminated the development of tension. These results are consistent with a linkage between Pi release and the steps leading to force production in the cross-bridge cycle.

scholarly journals Three-dimensional image reconstruction of insect flight muscle. I. The rigor myac layer.

1989 ◽  
Vol 109 (3) ◽  
pp. 1085-1102 ◽  
Author(s):  
K A Taylor ◽  
M C Reedy ◽  
L Córdova ◽  
M K Reedy
Keyword(s):  
Thin Filament ◽  
Flight Muscle ◽  
Insect Flight ◽  
Three Dimensional ◽  
Bridge Structure ◽  
Insect Flight Muscle ◽  
Single Filament ◽  
Cross Bridge ◽  
Cross Bridges

We have obtained detailed three-dimensional images of in situ cross-bridge structure in insect flight muscle by electron microscopy of multiple tilt views of single filament layers in ultrathin sections, supplemented with data from thick sections. In this report, we describe the images obtained of the myac layer, a 25-nm longitudinal section containing a single layer of alternating myosin and actin filaments. The reconstruction reveals averaged rigor cross-bridges that clearly separate into two classes constituting lead and rear chevrons within each 38.7-nm axial repeat. These two classes differ in tilt angle, size and shape, density, and slew. This new reconstruction confirms our earlier interpretation of the lead bridge as a two-headed cross-bridge and the rear bridge as a single-headed cross-bridge. The importance of complementing tilt series with additional projections outside the goniometer tilt range is demonstrated by comparison with our earlier myac layer reconstruction. Incorporation of this additional data reveals new details of rigor cross-bridge structure in situ which include clear delineation of (a) a triangular shape for the lead bridge, (b) a smaller size for the rear bridge, and (c) density continuity across the thin filament in the lead bridge. Within actin's regular 38.7-nm helical repeat, local twist variations in the thin filament that correlate with the two cross-bridge classes persist in this new reconstruction. These observations show that in situ rigor cross-bridges are not uniform, and suggest three different myosin head conformations in rigor.

scholarly journals ADP binding to myosin cross-bridges and its effect on the cross-bridge detachment rate constants.

1987 ◽  
Vol 89 (6) ◽  
pp. 905-920 ◽  
Author(s):  
M Schoenberg ◽  
E Eisenberg
Keyword(s):  
Dissociation Constant ◽  
Active Site ◽  
Rate Constants ◽  
Competitive Inhibition ◽  
Psoas Muscle ◽  
Nucleotide Analogues ◽  
Cross Bridge ◽  
Detachment Rate ◽  
The Cross ◽  
Cross Bridges

We have studied the binding of adenosine diphosphate (ADP) to attached cross-bridges in chemically skinned rabbit psoas muscle fibers and the effect of that binding on the cross-bridge detachment rate constants. Cross-bridges with ADP bound to the active site behave very similarly to cross-bridges without any nucleotide at the active site. First, fiber stiffness is the same as in rigor, which presumably implies that, as in rigor, all the cross-bridges are attached. Second, the cross-bridge detachment rate constants in the presence of ADP, measured from the rate of decay of the force induced by a small stretch, are, over a time scale of minutes, similar to those seen in rigor. Because ADP binding to the active site does not cause an increase in the cross-bridge detachment rate constants, whereas binding of nucleotide analogues such as adenyl-5'-yl imidodiphosphate (AMP-PNP) and pyrophosphate (PPi) do, it was possible, by using ADP as a competitive inhibitor of PPi or AMP-PNP, to measure the competitive inhibition constant and thereby the dissociation constant for ADP binding to attached cross-bridges. We found that adding 175 microM ADP to 4 mM PPi or 4 mM AMP-PNP produces as much of a decrease in the apparent cross-bridge detachment rate constants as reducing the analogue concentration from 4 to 1 mM. This suggests that ADP is binding to attached cross-bridges with a dissociation constant of approximately 60 microM. This value is quite similar to that reported for ADP binding to actomyosin subfragment-1 (acto-S1) in solution, which provides further support for the idea that nucleotides and nucleotide analogues seem to bind about as strongly to attached cross-bridges in fibers as to acto-S1 in solution (Johnson, R.E., and P. H. Adams. 1984. FEBS Letters. 174:11-14; Schoenberg, M., and E. Eisenberg. 1985. Biophysical Journal. 48:863-871; Biosca, J.A., L.E. Greene, and E. Eisenberg. 1986. Journal of Biological Chemistry. 261:9793-9800).

Cross-bridge mechanisms underlying the history-dependent properties of muscle spindles and stretch reflexes

2004 ◽  
Vol 82 (8-9) ◽  
pp. 569-576 ◽  
Author(s):  
T Richard Nichols ◽  
Timothy C Cope
Keyword(s):  
Mechanical Properties ◽  
Muscle Spindle ◽  
Muscle Spindles ◽  
Muscular Contraction ◽  
Cross Bridge ◽  
Nonlinear Mechanical ◽  
Reflex Compensation ◽  
Cross Bridges ◽  
Bridge Models ◽  
Kinetics Of

The effects of prior movement on the force responses of skeletal muscle are compared with the effects of movement history on the changes in firing rate of muscle spindle receptors. Prior release results in the linearization of the mechanical properties of skeletal muscles, which can be provisionally explained by cross-bridge models of muscular contraction. The history-dependence of responses of muscle spindle receptors in unanesthetized decerebrate preparations appears to result from the kinetics of cycling and noncycling cross-bridges. The results of this comparison indicate that the integration of mechanical properties of muscle and spindle receptor promotes stiffness regulation.Key words: predictive control, muscular stiffness, muscle receptors, reflex compensation, cross-bridge cycling, nonlinear mechanical properties, feline motor control.

Myosin cross-bridge kinetics in airway smooth muscle: a comparative study of humans, rats, and rabbits

2002 ◽  
Vol 282 (1) ◽  
pp. L83-L90 ◽  
Author(s):  
Y. Lecarpentier ◽  
F.-X. Blanc ◽  
S. Salmeron ◽  
J.-C. Pourny ◽  
D. Chemla ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Comparative Study ◽  
Mechanical Behavior ◽  
Airway Smooth Muscle ◽  
Rate Constants ◽  
Species Differences ◽  
Isometric Tension ◽  
New Formalism ◽  
Cross Bridge ◽  
Cross Bridges

To analyze the kinetics and unitary force of cross bridges (CBs) in airway smooth muscle (ASM), we proposed a new formalism of Huxley's equations adapted to nonsarcomeric muscles (Huxley AF. Prog Biophys Biophys Chem7: 255–318, 1957). These equations were applied to ASM from rabbits, rats, and humans ( n = 12/group). We tested the hypothesis that species differences in whole ASM mechanics were related to differences in CB mechanics. We calculated the total CB number per square millimeter at peak isometric tension (Ψ ×109), CB unitary force (Π), and the rate constants for CB attachment ( f 1) and detachment ( g 1 and g 2). Total tension, Ψ, and Π were significantly higher in rabbits than in humans and rats. Values of Π were 8.6 ± 0.1 pN in rabbits, 7.6 ± 0.3 pN in humans, and 7.7 ± 0.2 pN in rats. Values of Ψ were 4.0 ± 0.5 in rabbits, 1.2 ± 0.1 in humans, and 1.9 ± 0.2 in rats; f 1 was lower in humans than in rabbits and rats; g 2 was higher in rabbits than in rats and in rats than in humans. In conclusion, ASM mechanical behavior of different species was characterized by specific CB kinetics and CB unitary force.

scholarly journals Suppression of muscle contraction by vanadate. Mechanical and ligand binding studies on glycerol-extracted rabbit fibers.

1985 ◽  
Vol 86 (3) ◽  
pp. 305-327 ◽  
Author(s):  
J A Dantzig ◽  
Y E Goldman
Keyword(s):  
Muscle Fibers ◽  
Adenosine Diphosphate ◽  
Order Rate Constant ◽  
Rabbit Muscle ◽  
Binding Studies ◽  
Tension Development ◽  
Cross Bridge ◽  
Initial Rise ◽  
Cross Bridges ◽  
Myosin X

The suppression of tension development by orthovanadate (Vi) was studied in mechanical experiments and by measuring the binding of radioactive Vi and nucleotides to glycerol-extracted rabbit muscle fibers. During active contractions, Vi bound to the cross-bridges and suppressed tension with an apparent second-order rate constant of 1.34 X 10(3) M-1s-1. The half-saturation concentration for tension suppression was 94 microM Vi. The incubation of fibers in Vi relaxing or rigor solutions prior to initiation of active contractions had little effect on the initial rise of active tension. The addition of adenosine diphosphate (ADP) and Vi to fibers in rigor did not cause relaxation. Suppression of tension only developed during cross-bridge cycling. After slow relaxation from rigor in 1 mM Vi and low (50 microM) MgATP concentration (0 Ca2+), radioactive Vi and ADP were trapped within the fiber. This finding indicated the formation of a stable myosin X ADP X Vi complex, as has been reported in biochemical experiments with isolated myosin. Vi and ADP trapped within the fibers were released only by subsequent cross-bridge attachment. Vi and ADP were preferentially trapped under conditions of cross-bridge cycling in the presence of ATP rather than in relaxed fibers or in rigor with ADP. These results indicate that in the normal cross-bridge cycle, inorganic phosphate (Pi) is released from actomyosin before ADP. The resulting actomyosin X ADP intermediate can bind Vi and Pi. This intermediate probably supports force. Vi behaves as a close analogue of Pi in muscle fibers, as it does with isolated actomyosin.

scholarly journals Measuring myosin cross-bridge attachment time in activated muscle fibers using stochastic vs. sinusoidal length perturbation analysis

2011 ◽  
Vol 110 (4) ◽  
pp. 1101-1108 ◽  
Author(s):  
Bertrand C. W. Tanner ◽  
Yuan Wang ◽  
David W. Maughan ◽  
Bradley M. Palmer
Keyword(s):  
White Noise ◽  
Striated Muscle ◽  
Flight Muscle ◽  
Noise Analysis ◽  
Muscle Fibers ◽  
White Noise Analysis ◽  
Sinusoidal Analysis ◽  
Cross Bridge ◽  
Cross Bridges ◽  
Time Required

The average time myosin cross bridges remain bound to actin ( ton) can be measured by sinusoidal length perturbations (sinusoidal analysis) of striated muscle fibers using recently developed analytic methods. This approach allows measurements of ton in preparations possessing a physiologically relevant myofilament lattice. In this study, we developed an approach to measure ton in 5–10% of the time required for sinusoidal analysis by using stochastic length perturbations (white noise analysis). To compare these methods, we measured the influence of MgATP concentration ([MgATP]) on ton in demembranated myocardial strips from mice, sampling muscle behavior from 0.125 to 200 Hz with a 20-s burst of white noise vs. a 300-s series of sinusoids. Both methods detected a similar >300% increase in ton as [MgATP] decreased from 5 to 0.25 mM, differing by only 3–14% at any [MgATP]. Additional experiments with Drosophila indirect flight muscle fibers demonstrated that faster cross-bridge cycling kinetics permit further reducing of the perturbation time required to measure ton. This reduced sampling time allowed strain-dependent measurements of ton in flight muscle fibers by combining 10-s bursts of white noise during periods of linear shortening and lengthening. Analyses revealed longer ton values during shortening and shorter ton values during lengthening. This asymmetry may provide a mechanism that contributes to oscillatory energy transfer between the flight muscles and thoracic cuticle to power flight. This study demonstrates that white noise analysis can detect underlying molecular processes associated with dynamic muscle contraction comparable to sinusoidal analysis, but in a fraction of the time.

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