A model of force production that explains the lag between crossbridge attachment and force after electrical stimulation of striated muscle fibers

Bagni, Maria Angela; Cecchi, Giovanni; Schoenberg, Mark J.

doi:10.1016/s0006-3495(88)83046-7

Cited by 48 publications

(41 citation statements)

References 33 publications

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“…Force and stiffness started to rise with no detectable difference in the latent period after the first stimulus. In accordance with previous results (Bressler & Clinch, 1974;Schoenberg & Wells, 1984;Cecchi, Griffiths & Taylor, 1986;Ford, Huxley & Simmons, 1986;Bagni, Cecchi & Schoenberg, 1988;Hatta, Sugi & Tamura, 1988) stiffness was found to increase more steeply and to reach its maximum values at an earlier time during the tetanus than did force. In eleven experiments performed at 2 10 jtm sarcomere length (1I8-3-5 TC) the time required for attaining 90% of maximum force and 90°% of maximum stiffness was 134 + 4 and 87+5 ms, respectively.…”

Section: Time Course Offorce and Stiffness During Isometric Tetanussupporting

confidence: 92%

Changes in force and stiffness induced by fatigue and intracellular acidification in frog muscle fibres.

Edman

Lou

1990

The Journal of Physiology

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1. Changes in force and stiffness were recorded simultaneously during 1 s isometric (fixed ends) tetani of single fibres isolated from the anterior tibialis muscle of Rana temporaria (temperature 1-3 degrees C; sarcomere length, 2.10 micron). Stiffness was measured as the change in force that occurred in response to a 4 kHz sinusoidal length oscillation of the fibre. Some experiments were performed in which stiffness was determined from a fast (0.2 ms) length step that was applied to a 'tendon-free' segment of the muscle fibre during the tetanus plateau. 2. A moderate degree of fatigue was produced by decreasing the time between tetani from 300 s (control) to 15 s. By this treatment the maximum tetanic force (Ftet) was reversibly reduced to 70-75% of the control value. Maximum tetanic stiffness (Stet) was related to Ftet according to the following regression (both variables expressed as percentage of their control values): Stet = 0.369 Ftet + 62.91 (correlation coefficient, 0.95; P less than 0.001). A 25% decrease in isometric force during fatigue was thus associated with merely 9% reduction of fibre stiffness. 3. Whereas the rate of rise of force during tetanus was markedly reduced by fatiguing stimulation, the rate of rise of stiffness was only slightly affected. 4. Intracellular acidification (produced by raised extracellular CO2 concentration) largely reproduced the contractile changes observed during fatigue. However, for a given decrease in tetanic force there was a smaller reduction in fibre stiffness during acidosis than during fatigue. 5. Caffeine (0.5 mM) added to the fibre after development of fatigue and intracellular acidosis greatly potentiated the isometric twitch but did not affect maximum tetanic force. This finding provides evidence that the contractile system was fully activated during the tetanus plateau both in the fatigued state and during acidosis. 6. The results suggest that the decrease in contractile strength after frequent tetanization (intervals between tetani, 15 s) is attributable to altered kinetics of cross-bridge function leading to reduced number of active cross-bridges and, most significantly, to reduced force output of the individual bridge. The possible role of increased intracellular H+ concentration in the development of muscle fatigue is discussed.

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Section: Time Course Offorce and Stiffness During Isometric Tetanussupporting

confidence: 92%

Changes in force and stiffness induced by fatigue and intracellular acidification in frog muscle fibres.

Edman

Lou

1990

The Journal of Physiology

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“…The reasons for these differences are not known, particularly considering that the later studies by Palmer and Kentish were carried out on the same preparation using conditions similar to those in this study. Nevertheless, the slowing of the tension time course may represent a decrease in cross-bridge turnover during the rising phase of tension development and is consistent with results from earlier studies on fast and slow skeletal muscle using a real-time phosphate assay (He et al, 1997) or mechanical transients (Ford et al, 1986;Bagni et al, 1988;Josephson and Edman, 1998). The early rapid rates for crossbridge binding and force generation are in accordance with the results from these later mechanical studies of skeletal muscle indicating that the rate for isometric tension recovery after a small quick length change (Ford et al, 1986;Bagni et al, 1988) or maximal shortening velocity (Josephson and Edman, 1998) is faster when applied during the rising phase of a tetanus than when applied on the plateau.…”

Section: Comparison With Other Studiessupporting

confidence: 89%

Activation Kinetics of Skinned Cardiac Muscle by Laser Photolysis of Nitrophenyl-EGTA

Martin

Bell

Ellis‐Davies

et al. 2004

Biophysical Journal

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The kinetics of Ca(2+)-induced contractions of chemically skinned guinea pig trabeculae was studied using laser photolysis of NP-EGTA. The amount of free Ca(2+) released was altered by varying the output from a frequency-doubled ruby laser focused on the trabeculae, while maintaining constant total [NP-EGTA] and [Ca(2+)]. The time courses of the rise in stiffness and tension were biexponential at 23 degrees C, pH 7.1, and 200 mM ionic strength. At full activation (pCa < 5.0), the rates of the rapid phase of the stiffness and tension rise were 56 +/- 7 s(-1) (n = 7) and 48 +/- 6 s(-1) (n = 11) while the amplitudes were 21 +/- 2 and 23 +/- 3%, respectively. These rates had similar dependencies on final [Ca(2+)] achieved by photolysis: 43 and 50 s(-1) per pCa unit, respectively, over a range of [Ca(2+)] producing from 15% to 90% of maximal isometric tension. At all [Ca(2+)], the rise in stiffness initially was faster than that of tension. The maximal rates for the slower components of the rise in stiffness and tension were 4.1 +/- 0.8 and 6.2 +/- 1.0 s(-1). The rate of this slower phase exhibited significantly less Ca(2+) sensitivity, 1 and 4 s(-1) per pCa unit for stiffness and tension, respectively. These data, along with previous studies indicating that the force-generating step in the cross-bridge cycle of cardiac muscle is marginally sensitive to [Ca(2+)], suggest a mechanism of regulation in which Ca(2+) controls the attachment step in the cross-bridge cycle via a rapid equilibrium with the thin filament activation state. Myosin kinetics sets the time course for the rise in stiffness and force generation with the biexponential nature of the mechanical responses to steps in [Ca(2+)] arising from a shift to slower cross-bridge kinetics as the number of strongly bound cross-bridges increases.

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“…In accordance with previous observations at low temperature in frog muscle (3,8,20,26,29), Fig. 1, C and D, demonstrates that stiffness was in the lead of tension during the rising phase of the tetanus, and this applies to both low and high temperatures.…”

Section: Resultssupporting

confidence: 92%

Effects of intracellular acidification and varied temperature on force, stiffness, and speed of shortening in frog muscle fibers

Radzyukevich¹,

Edman²

2004

American Journal of Physiology-Cell Physiology

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Radzyukevich, T., and K. A. P. Edman. Effects of intracellular acidification and varied temperature on force, stiffness, and speed of shortening in frog muscle fibers. Am J Physiol Cell Physiol 287: C106 -C113, 2004. First published March 3, 2004 10.1152/ajpcell. 00472.2003.-This study aimed to establish whether the temperaturedependent effect of acidification on maximum force observed in mammalian muscles also applies to frog muscle. Measurements of force, stiffness, and unloaded velocity of shortening in intact single muscle fibers from the anterior tibialis muscle of Rana temporaria were performed between 0 and 22°C during fused tetani in H2CO3-CO2-buffered Ringer solution with pH adjusted to 7.0 and 6.3, respectively. The force-to-stiffness ratio increased as a rectilinear function of temperature between 0 and 20°C at pH 7.0. Lowering the pH to 6.3 reduced the tetanic force by 13.5 Ϯ 1.2 and 11.5 Ϯ 1.4% at 2.8 and 20.5°C, respectively, with only a minor reduction in fiber stiffness. The maximum speed of shortening was decreased by lowered pH by 12.9 Ϯ 1.5 and 7.8 Ϯ 1.1% at low and high temperature, respectively. Acidification increased the time to reach 70% of maximum force by 18.0% at ϳ2°C; the same pH change performed at ϳ20°C in the same fibers reduced the rise time by 24.1%. The same increase in the rate of rise of force at high temperature was also found at normal pH after the fibers were fatigued by frequent stimulation. It is concluded that, in frog muscle, the force-depressant effect of acidification does not vary significantly with temperature. By contrast, acidification affects the onset of activation in a manner that is critically dependent on temperature. muscle contraction; pH THERE IS ABUNDANT EVIDENCE that the intracellular pH is an important determinant of the contractile performance of striated muscle. Early experiments (4, 41, 46), later confirmed and extended (e.g., 5, 39, 47), have demonstrated that lowering the pH from 8.0 to 6.0 reduces the ATPase activity of calciumactivated myofibrils in suspension. A change of the intracellular pH also affects the excitation-contraction coupling. A drop in pH has thus been shown to shift the relationship between isometric force and Ca 2ϩ toward higher concentrations of calcium and, furthermore, to reduce the maximum force output at saturating calcium concentrations (2, 24, 52).The influence of intracellular pH on the kinetic properties of the contractile system has previously been explored in considerable detail during tetanic activity of frog single muscle fibers, i.e., under conditions where the myofilament system has been fully activated (14, 15, 20 -22, 54). Results from such studies show that a drop in pH from 7.0 to ϳ6.5 leads to lowered capacity to produce force but only to a minor change in fiber stiffness (Ref. 20; see also Ref. 44 for frog whole sartorius muscle), suggesting that the decrease in active force is mainly due to reduced force output of the individual cross bridges with little change in the actual number of attached bridges. L...

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A model of force production that explains the lag between crossbridge attachment and force after electrical stimulation of striated muscle fibers

Cited by 48 publications

References 33 publications

Changes in force and stiffness induced by fatigue and intracellular acidification in frog muscle fibres.

Changes in force and stiffness induced by fatigue and intracellular acidification in frog muscle fibres.

Activation Kinetics of Skinned Cardiac Muscle by Laser Photolysis of Nitrophenyl-EGTA

Effects of intracellular acidification and varied temperature on force, stiffness, and speed of shortening in frog muscle fibers

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