Caffeine suppresses length dependency of Ca2+ sensitivity of skinned striated muscle

Beer, E. L. de; Grundeman, R. L. F.; Wilhelm, Adriana; Caljouw, C. J.; Klepper, D.; Schiereck, P.

doi:10.1152/ajpcell.1988.254.4.c491

Cited by 68 publications

(9 citation statements)

References 32 publications

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“…There are two possible explanations for this difference with the present results. (i) The effects of caffeine on Ca2" sensitivity have been reported to be enhanced at short sarcomere lengths (De Beer et al 1988). This could explain the prominent maintained contracture seen in the present unloaded contractions.…”

Section: Discussionmentioning

confidence: 99%

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The role of [Ca2+]i and [Ca2+] sensitization in the caffeine contracture of rat myocytes: measurement of [Ca2+]i and [caffeine]i.

O’Neill

Donoso

Eisner

1990

The Journal of Physiology

154

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Section: Discussionmentioning

confidence: 99%

“…). Furthermore we have taken no account of the observation that the effects of caffeine depend on sarcomere length(De Beer et al 1988) and will therefore change during the contracture.…”

mentioning

confidence: 99%

The role of [Ca2+]i and [Ca2+] sensitization in the caffeine contracture of rat myocytes: measurement of [Ca2+]i and [caffeine]i.

O’Neill

Donoso

Eisner

1990

The Journal of Physiology

154

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“…Even less is known about how caffeine suppresses maximum force. One possibility is that it is due to an increase in myofilament lattice spacing (de Beer et al 1988). It would seem that the depression of force is not related to Ca2+ sensitization, since some Ca2+ sensitizing agents such as sulmazole enhance maximum force (Lamont & Miller, 1992); in addition, force and Ca2" sensitivity were affected differentially, in that caffeine reduced maximum force similarly in the two muscle types (Fig.…”

Section: Maximum Force Production In Skinned Fibresmentioning

confidence: 96%

“…The rise in pCa50 induced by caffeine was three times greater for trabeculae (0-31 + 0 04, n = 5) than for skeletal fibres (0 09 + 0 01, n = 4). To see whether this difference was due to the longer SL in the psoas fibres, since it has been reported that the Ca2" sensitization by caffeine is less at longer SL (de Beer, Grundemann, Wilhelm, Caljouw, Klepper & Schiereck, 1988), in separate 20 - experiments we varied the SL in skeletal fibres over a wide range (1P6-2-8 ,um). However, the increase in pCa50 induced by caffeine in psoas muscles was found to be independent of SL (results not shown), suggesting that the greater Ca2+sensitizing action of caffeine in cardiac fibres compared with skeletal fast-twitch fibres was due to a true difference between muscle types.…”

Section: Caffeinementioning

confidence: 99%

The role of troponin C in modulating the Ca2+ sensitivity of mammalian skinned cardiac and skeletal muscle fibres.

Palmer

Kentish

1994

The Journal of Physiology

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1. We investigated the effects of acidosis, inorganic phosphate (Pi) and caffeine on the Ca2" affinity of isolated fast-twitch skeletal and cardiac troponin C (TnC), labelled with fluorescent probes to report Ca2" binding to the regulatory sites. We also measured the effects of these interventions on the maximum force development and the Ca2" sensitivity of skinned fibres from fast-twitch skeletal muscle and cardiac muscle, as has been done previously. The two types of experiment were carried out under similar solution conditions, so that we could assess the contribution of any direct actions on TnC to the modulation of Ca2" sensitivity in the skinned muscle fibres.2. In skinned fibres, acidosis (decreasing pH from 7 0 to 6 2) and Pi (20 mM) suppressed maximum force to the same extent within a given muscle type, but had greater effects on cardiac fibres compared with skeletal fibres. Caffeine (20 mM) depressed maximum force equally in cardiac and skeletal muscle. Thus, the fall of force induced by acidosis or P1 may involve a different mechanism from that induced by caffeine. 3. Skinned skeletal fibres were more Ca2" sensitive than cardiac fibres by 0-29 pCa units (pCa = -log1O[Ca2"]). Isolated skeletal TnC also had a greater Ca2" affinity than cardiac TnC, by 0-20 pCa units. These results suggest that the Ca2+ sensitivity of skinned fibres is at least partly determined by the type of TnC present.4. Acidosis reduced the Ca2+ sensitivity of force in skinned fibres profoundly and had a 2-fold greater effect in cardiac muscle than skeletal muscle (falls in pCa for 50% activation, pCa50, were 1-09 and 0 55, respectively). Acidosis also reduced the Ca2+ affinity of TnC, again having double the effect on the pCa50 for cardiac TnC (0 58) as on that for skeletal TnC (0 28). The greater effect of acidosis on cardiac skinned fibres, compared with skeletal, may be partly explained, therefore, by the type of TnC present, and one-half of the effect on fibres may be attributed to the direct effect of H+ on TnC.5. Pi reduced the Ca2`sensitivity of force in skeletal and cardiac skinned fibres by 0 30 and 0X19 pCa units, respectively. However, the Ca2+ affinity of isolated cardiac and skeletal TnC was unaffected by Pi, indicating that the decrease in muscle Ca2+ sensitivity is not mediated by a direct action of Pi on TnC.6. Caffeine increased the Ca2+ sensitivity of cardiac skinned fibres by 0f31 pCa units, which was 3 times greater than for the skeletal fibres (0 09 pCa units). Caffeine had no effect on Ca2+ binding to isolated TnC, so its Ca2+ sensitizing action on skinned fibres is unlikely to be due to a direct effect on TnC. 7. We conclude that the different Ca2+ and pH sensitivities of cardiac and skeletal fibres are partly accounted for by the properties of the TnC present. However, the actions of caffeine and Pi on skinned fibres are not explained by any direct actions on TnC. Some of the Pi-induced decrease in Ca2`sensitivity probably results from a reduced Ca2+ affinity of TnC in the thin filament as a result of a decr...

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“…A set-up similar to that described by De Beer et al (1988) was used to monitor tension development in the labelled muscle fibres. The fibres were mounted between two stainless steel clips, one of which was attached to a strain gauge force transducer (AME 801, Aksjeselskapet Mikro Elektronikk).…”

Section: Tension Development Of Labelled Muscle Fibresmentioning

confidence: 99%

A fluorescence depolarization study of the orientational distribution of crossbridges in muscle fibres

et al. 1994

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A fluorescence depolarization study of the orientational distribution of crossbridges in dye-labelled muscle fibres is presented. The characterization of this distribution is important since the rotation of crossbridges is a key element in the theory of muscle contraction. In this study we exploited the advantages of angle-resolved experiments to characterize the principal features of the orientational distribution of the crossbridges in the muscle fibre. The directions of the transition dipole moments in the frame of the dye and the orientation and motion of the dye relative to the crossbridge determined previously were explicitly incorporated into the analysis of the experimental data. This afforded the unequivocal determination of all the second and fourth rank order parameters. Moreover, this additional information provided discrimination between different models for the orientational behaviour of the crossbridges. Our results indicate that no change of orientation takes place upon a transition from rigor to relaxation. The experiments, however, do no rule out a conformational change of the myosin S1 during the transition.

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Caffeine suppresses length dependency of Ca2+ sensitivity of skinned striated muscle

Cited by 68 publications

References 32 publications

The role of [Ca2+]i and [Ca2+] sensitization in the caffeine contracture of rat myocytes: measurement of [Ca2+]i and [caffeine]i.

The role of [Ca2+]i and [Ca2+] sensitization in the caffeine contracture of rat myocytes: measurement of [Ca2+]i and [caffeine]i.

The role of troponin C in modulating the Ca2+ sensitivity of mammalian skinned cardiac and skeletal muscle fibres.

A fluorescence depolarization study of the orientational distribution of crossbridges in muscle fibres

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