Is the change in intracellular pH during fatigue large enough to be the main cause of fatigue?

Renaud, Julie; Allard, Yvon E.; Mainwood, G. W.

doi:10.1139/y86-130

Cited by 45 publications

(35 citation statements)

References 4 publications

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“…pHi values in unfatigued andfatigued sartorius muscles The pHi of unfatigued sartorius muscles from Rana pipiens is comparable to the pHi measured in semitendinosus muscles of the same species (Abercrombie, Putnam & Roos, 1983), and sartorius muscles of Rana temporaria (Curtin, 1986a). The decreases in pHi during fatigue development are similar to those obtained from muscle fibre type 1 of Xenopus laevis (Westerblad & Liinnergren, 1988), but they are 2 times greater than those obtained previously from frog sartorius muscles exposed to HC03- (Renaud et al 1986). This effect of buffer species on how pHi changes has also been reported in ischaemic ventricular muscles and Purkinje fibres (Vanheel, Leybaert, de Hemptine & Leusen, 1987;Bountra, Kaila & Vaughan-Jones, 1988).…”

Section: Effects On Pho and L-lactic Acid On Tetanic Force Recoverysupporting

confidence: 80%

“…This is further supported by the following evidence. First, the net decrease in pHi observed at the end of a fatigue stimulus is too small to account for the change in force (Meyer, Kushmerick & Dillon, 1983;Renaud et al 1986). Second, muscle fatigue may occur without any change in pHi in patients suffering from McArdle disease (Shulman, 1980) or following strenuous but short bouts of exercise (V0llestad & Sejersted, 1988).…”

Section: Introductionmentioning

confidence: 99%

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The effect of lactate on intracellular pH and force recovery of fatigued sartorius muscles of the frog, Rana pipiens.

Renaud

1989

The Journal of Physiology

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SUMMARY1. The effects of pHo (extracellular pH) and lactic acid on pHi (intracellular pH) and tetanic force were examined in frog sartorius muscle. Ion-selective microelectrodes were used to measure pHi. Tetanic force was elicited by field stimulation.Experiments were performed in HEPES-buffered solution equilibrated with 100% 02.2. Mean pHi values (+ S.E.M.) of unfatigued frog sartorius muscles were 7-14 + 0-02 and 7 05 + 0 09 at pHo 7-2 and 6-4, respectively.3. A stimulation at a rate of one 100 ms tetanic contraction per second for 3 min reduced pHi to 6-21 + 0-09 and 6-20 + 0-04 at pHo 7-2 and 6-4, respectively. Meanwhile at pHo 7-2, the tetanic force (defined as the maximum force developed during a tetanus) decreased by 82-9 + 2-6 %, the maximum rate of relaxation decreased, by 92-9 + 0 9 %, and the rate constant of the relaxation decreased by 88-5 + 1-6 %. At pHo 6-4, the decrease in tetanic force, maximum rate of relaxation and rate constant were 90-6 + 1-8 %, 93-8 + 0 5 and 87-5 + 2-7 %, respectively.4. The maximum rates of recovery of pHi following fatigue were 0-068 + 0-05 and 0-025 + 0.05 pH units min-' at pHo 7-2 and 6-4, respectively. Recovery of normal tetanic force and relaxation rate was also slower at acidic pHo than at neutral pHo.5. In the presence of 40 mmol 1-' L-lactic acid at pHo 7-2, the maximum rate of pHi recovery following fatigue was only 0-027 +0-03 pH units min-1 at pHo 7-2. The presence of lactic acid also reduced the recovery of the relaxation phase, but not the recovery of tetanic force.6. It is suggested that pHi recovery is not a limiting factor for tetanic force recovery and that the extracellular H+ inhibits tetanic force recovery by acting at a site located on the outer surface of the sarcolemma. The recovery of the relaxation phase is believed to be pHi dependent.

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Section: Effects On Pho and L-lactic Acid On Tetanic Force Recoverysupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

The effect of lactate on intracellular pH and force recovery of fatigued sartorius muscles of the frog, Rana pipiens.

Renaud

1989

The Journal of Physiology

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“…Some investigations point to a critical role for H+ accumulation (Sahlin, Edstr6m, Sjoholm & Hultman, 1981; and see Renaud, Allard & Mainwood, 1986), although work with metabolically inhibited muscles contradicts this (Parkinson, 1933;Edwards et al 1975). It has also been suggested that a combination of metabolite changes leading to a reduction in the free energy of ATP hydrolysis could be the cause of the slowing (Dawson et al 1980).…”

Section: Introductionmentioning

confidence: 99%

The metabolic causes of slow relaxation in fatigued human skeletal muscle.

Cady

Elshove

Jones

et al. 1989

The Journal of Physiology

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SUMMARY1. The relationship between slowing of relaxation and changes of intracellular pH and phosphorous metabolites has been examined in human skeletal muscle during the development of fatigue and subsequent recovery. Results obtained with normal subjects have been compared with those from a subject with myophosphorylase deficiency (MPD) who produced no H+ from glycolysis during exercise and therefore afforded the opportunity of assessing the role of H+ in the slowing of relaxation.2. Subjects fatigued the first dorsal interosseous muscle in a stepwise fashion under ischaemic conditions, with intervals between the fatiguing contractions during which the relaxation rate was measured from brief tetanic contractions and the muscle phosphorous metabolites and pH were measured by nuclear magnetic resonance spectroscopy.3. After 21 s maximal voluntary contraction under ischaemic conditions, relaxation in the MPD subject slowed to approximately 50% of the rate in the fresh muscle at a time when the intramuscular pH had not changed. This demonstrates that there is a mechanism causing slowing of relaxation that is independent of H+ accumulation.4. The normal subjects showed a slow recovery of relaxation compared to the MPD subject when the circulation was restored. The main difference in the intracellular metabolite concentrations between MPD and normal subjects at this time was that, for the latter, the pH remained low (around 6 5) for at least 60 s after the circulation was restored. The results suggest that the slow recovery is a consequence of continuing acidosis, i.e. the existence of a pH-dependent mechanism of slowing.5. The existence of a pH-dependent mechanism was further indicated by the fact that for the normal subjects, for a similar intracellular concentration of phosphocreatine, relaxation of the recovering muscle was approximately half that of the fatiguing muscle. This was at a time when the pH of the recovering muscle was 0 3-0{4 units less than in the partially fatigued muscle.6. The results show that in normal muscle there are at least two processes that t Present address:

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“…This is regularly observed in frog muscle preparations at the low temperatures generally used (e.g., Refs. 20,22,44). The reduced speed of force development is at least partly attributable to the change of the force-velocity relationship that occurs under these conditions leading to a lower speed of shortening at low and intermediate loads (15,22).…”

Section: Discussionmentioning

confidence: 99%

“…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. Lowered intracellular pH also leads to a decrease in the maximum speed of shortening, as originally demonstrated by Edman and Mattiazzi (22) using the slack-test method (17).…”

mentioning

confidence: 96%

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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Is the change in intracellular pH during fatigue large enough to be the main cause of fatigue?

Cited by 45 publications

References 4 publications

The effect of lactate on intracellular pH and force recovery of fatigued sartorius muscles of the frog, Rana pipiens.

The effect of lactate on intracellular pH and force recovery of fatigued sartorius muscles of the frog, Rana pipiens.

The metabolic causes of slow relaxation in fatigued human skeletal muscle.

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

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