Influence of inorganic phosphate and pH on ATP utilization in fast and slow skeletal muscle fibers

Potma, E. J.; Graas, I. A. Van; Stienen, G. J. M.

doi:10.1016/s0006-3495(95)80129-3

Cited by 75 publications

(92 citation statements)

References 43 publications

(90 reference statements)

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“…One prediction of the proposed mechanism that P i can rebind to the AM.ADP state and cause dissociation from strongly bound state, while still being able to complete the ATPase cycle, is that the process would decrease myosin's duty ratio (the proportion of the ATPase cycle spent strongly bound to actin). This assumes, of course, that the total cycle time is either unchanged or increased, which seems robust based on the effects of P i of myosin's ATPase rate in fibers (30,31). Therefore, to test this prediction of our model, we measured the effect of P i on myosin's duty ratio at 2 mM ATP.…”

Section: Relevance To Previous Workmentioning

confidence: 98%

“…While there is little structural evidence for a lowaffinity M.ADP state (13), indirect evidence exists suggesting that the release of P i and ADP can indeed occur quite rapidly off actin under certain conditions. For example, elevated levels of P i have a much greater effect on force than the ATPase rate in muscle fibers (30,31), suggesting product release continues to be quite rapid off actin. In fact, efforts to model these data appear to require the relatively rapid release of P i and ADP from myosin while off actin (19) to accurately fit the ATPase results.…”

Section: Relevance To Previous Workmentioning

confidence: 99%

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Phosphate enhances myosin-powered actin filament velocity under acidic conditions in a motility assay

Debold

Turner

Stout

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

102

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Debold EP, Turner MA, Stout JC, Walcott S. Phosphate enhances myosin-powered actin filament velocity under acidic conditions in a motility assay. Am J Physiol Regul Integr Comp Physiol 300: R1401-R1408, 2011. First published February 23, 2011 doi:10.1152/ajpregu.00772.2010.-Elevated levels of inorganic phosphate (Pi) are believed to inhibit muscular force by reversing myosin's force-generating step. These same levels of Pi can also affect muscle velocity, but the molecular basis underlying these effects remains unclear. We directly examined the effect of Pi (30 mM) on skeletal muscle myosin's ability to translocate actin (Vactin) in an in vitro motility assay. Manipulation of the pH enabled us to probe rebinding of Pi to myosin's ADP-bound state, while changing the ATP concentration probed rebinding to the rigor state. Surprisingly, the addition of Pi significantly increased Vactin at both pH 6.8 and 6.5, causing a doubling of Vactin at pH 6.5. To probe the mechanisms underlying this increase in speed, we repeated these experiments while varying the ATP concentration. At pH 7.4, the effects of Pi were highly ATP dependent, with Pi slowing Vactin at low ATP (Ͻ500 M), but with a minor increase at 2 mM ATP. The Pi-induced slowing of Vactin, evident at low ATP (pH 7.4), was minimized at pH 6.8 and completely reversed at pH 6.5. These data were accurately fit with a simple detachment-limited kinetic model of motility that incorporated a Pi-induced prolongation of the rigor state, which accounted for the slowing of Vactin at low ATP, and a Pi-induced detachment from a strongly bound post-power-stroke state, which accounted for the increase in Vactin at high ATP. These findings suggest that Pi differentially affects myosin function: enhancing velocity, if it rebinds to the ADP-bound state, while slowing velocity, if it binds to the rigor state.fatigue; cross-bridge cycle; muscle contraction MUSCULAR FORCE AND MOTION are generated through the cyclical interaction of actin and myosin, in a process ultimately powered by the hydrolysis of ATP (Fig. 1). In the 1980s, several investigations established that elevated levels of organic phosphate (P i ) reduced muscular force, leading to the notion that P i release by myosin was closely associated with force generation (12) and the rotation of the lever arm (2). This hypothesis postulates that P i rebinds to myosin (M) in a state in which myosin is strongly bound to both actin (A) and ADP (AM.ADP) and, in one or more steps, reverses the forcegenerating step, leading to an increase in the population of the weakly bound myosin, in the M.ADP.P i state (32). While competing theories exist (3), models based on the P i -induced detachment can account for much of the effect on muscular force (26). However, the effects of P i on muscle's shortening velocity have been more difficult to explain using the same model.While the earliest experiments in muscle fibers suggested that P i had no effect on unloaded shortening velocity (V us ) (7), subsequent efforts revealed that P i could induc...

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Section: Relevance To Previous Workmentioning

confidence: 98%

Section: Relevance To Previous Workmentioning

confidence: 99%

Phosphate enhances myosin-powered actin filament velocity under acidic conditions in a motility assay

Debold

Turner

Stout

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

102

View full text Add to dashboard Cite

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“…Temperature was kept constant at 12°C throughout the experiment. Low temperatures, far from physiological, are generally used for skinned preparations (12°C: see Sweeney et al 1988;Bottinelli et al 1994a,b;or 15°C: Greaser et al 1988;Potma, Stienen Barends & Elzinga, 1994;Potma, van Graas & Stienen, 1995;Potma & Stienen, 1996). At higher temperatures (1) skinned fibres deteriorate quickly , (2) ATP consumption may increase more than its supply and (3) the duration of the shortening phases is reduced.…”

Section: Experimental Protocolmentioning

confidence: 99%

“…A slow continuous decline of the absorbance baseline was generally visible even before the fibre was immersed in the solution. This change was the combined result of NADH bleaching by the intense UV light and ATP hydrolysis by contaminanting phosphatases present in the solutions (Potma et al 1995). Superimposed on the background decline, a more pronounced decrease in absorbance began as soon as the fibre was immersed in the recording chamber.…”

Section: Data Recording and Analysismentioning

confidence: 99%

Chemo‐mechanical energy transduction in relation to myosin isoform composition in skeletal muscle fibres of the rat

Reggiani

Potma²,

Bottinelli

et al. 1997

The Journal of Physiology

114

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ATP consumption and force development were determined in single skinned muscle fibres of the rat at 12 °C. Myofibrillar ATPase consumption was measured photometrically from NADH oxidation which was coupled to ATP hydrolysis. Myosin heavy chain (MHC) and light chain (MLC) isoforms were identified by gel electrophoresis. Slow fibres (n= 14) containing MHCI and fast fibres (n= 18) containing MHCIIB were compared. Maximum shortening velocity was 1.02 ± 0.63 and 3.05 ± 0.23 lengths s−1, maximum power was 1.47 ± 0.22 and 9.59 ± 0.84 W l−1, and isometric ATPase activity was 0.034 ± 0.003 and 0.25 ± 0.01 mM s−1 in slow and in fast fibres, respectively. In fast as well as in slow fibres ATP consumption during shortening increased above isometric ATP consumption. The increase was much greater in fast fibres than in slow fibres, but became similar when expressed relative to the isometric ATPase rate. Efficiency was calculated from mechanical power and free energy change associated with ATP hydrolysis. Maximum efficiency was larger in slow than in fast fibres (0.38 ± 0.04 versus 0.28 ± 0.03) and was reached at a lower shortening velocity. Within the group of fast fibres efficiency was lower in fibres which contained more MLC3f. We conclude that both MHC and essential MLC isoforms contribute to determine efficiency of chemo‐mechanical transduction.

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“…Some researchers have argued that increases in the influx of H + , and PO 4 3-into the muscle fiber are associated not only to the mechanism of muscle fatigue, but to the FD, decreased passive tension during the shortening phase. The muscle fiber size should also be taken into account, whereas the concentrations of H + , and PO 4 3-in a proportional relationship that is, higher fiber size, the greater the influx of H + , and PO 4 3- (40,61,71,72,73,74,75,76). As the both ions driven cannot be removed quickly, one can speculate that FD could not be abolished instantaneously after quick deactivation muscle, but should persist for a long period of time (6,7,32).…”

Section: Theory Of Non-uniformity and Instability Of Sarcomerementioning

confidence: 99%

Variation in isometric force after active shortening and lengthening and their mechanisms: a review

Lima

Farinatti²,

Monteiro

et al. 2014

Fisioter. mov.

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Introduction:The isometric force history dependence of skeletal muscle has been studied along the last one hundred years. Several theories have been formulated to explain and establish the causes of the phenomenon, but not successfully, as they have not been fully accepted and demonstrated, and much controversy on such a subject still remains. Objective: To present a systematic literature review on the dynamics of the mechanisms of force depression and force enhancement after active shortening and lengthening, respectively, identifying the key variables involved in the phenomenon, and to date to present the main theories and hypothesis developed trying to explaining it. Method: The procedure of literature searching complied the major databases, including articles either, those which directly investigated the phenomena of force depression and force enhancement or those which presented possible causes and mechanisms associated with their respective events, from the earliest studies published until the year of 2010. Results: 97

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Influence of inorganic phosphate and pH on ATP utilization in fast and slow skeletal muscle fibers

Cited by 75 publications

References 43 publications

Phosphate enhances myosin-powered actin filament velocity under acidic conditions in a motility assay

Phosphate enhances myosin-powered actin filament velocity under acidic conditions in a motility assay

Chemo‐mechanical energy transduction in relation to myosin isoform composition in skeletal muscle fibres of the rat

Variation in isometric force after active shortening and lengthening and their mechanisms: a review

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