scholarly journals Probenecid affects sarcoplasmic reticulum Ca2+ release and depresses contractile activation in mouse skeletal muscle

2021 ◽  
Vol 154 (9) ◽  
Author(s):  
Francisco Jaque-Fernandez ◽  
Bruno Allard ◽  
Laloe Monteiro ◽  
Aude Lafoux ◽  
Corinne Huchet ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Extracellular Space ◽  
Purinergic Signaling ◽  
Muscle Fibers ◽  
Atp Release ◽  
Extracellular Medium ◽  
Mouse Muscle ◽  
Therapeutic Benefits ◽  
Ec Coupling

Pannexins are plasma membrane heptameric channels mediating ATP release from the cytosol to the extracellular space. Skeletal muscle activity is associated with Pannexin 1 (Panx1) channels activation, ATP release out to the extracellular space and subsequent activation of purinergic signaling pathways. In agreement, recent evidence has shown molecular and functional interactions between Panx1 and the excitation–contraction (EC) coupling machinery of skeletal muscle. In this framework, we tested whether pharmacological effectors of Panx1 affect EC coupling in differentiated muscle fibers. Using confocal detection of cytosolic Ca2+ in voltage-clamped mouse muscle fibers, we found that the Panx1 blocker probenecid (1 mM) affects intracellular Ca2+ handling and EC coupling: acute application of probenecid generates a rise in resting Ca2+ that also occurs in nominally Ca2+-free extracellular medium. This effect is associated with a reduction of Ca2+ release through the sarcoplasmic reticulum (SR) Ca2+ channel RYR1. The effect of probenecid persists with time, with muscle fibers incubated for 30 min in the presence of the drug exhibiting a 40% reduction in peak SR Ca2+ release. Under the same conditions, the other Panx1 blocker carbenoxolone (50 µM) produced a 70% reduction in peak SR Ca2+ release. Application of probenecid on electrically stimulated whole mouse muscle induced a slight rise in resting tension and a >50% reduction of tetanic force after 30 min of incubation. Our results provide further support for the strong links between Panx1 function and EC coupling. Because probenecid is used both in the clinic for several types of therapeutic benefits and as a hiding agent for doping in sport, our results question whether potential adverse muscular effects may have, so far, been overlooked.

scholarly journals Major contribution of sarcoplasmic reticulum Ca2+ depletion during long-lasting activation of skeletal muscle

2013 ◽  
Vol 141 (5) ◽  
pp. 557-565 ◽  
Author(s):  
Gaëlle Robin ◽  
Bruno Allard
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Voltage Dependence ◽  
Muscle Fibers ◽  
Voltage Sensitivity ◽  
Mouse Muscle ◽  
Physiological Conditions ◽  
Relative Contribution ◽  
Voltage Dependent ◽  
Steady State Inactivation

Depolarization of skeletal muscle fibers induces sarcoplasmic reticulum (SR) Ca2+ release and contraction that progressively decline while depolarization is maintained. Voltage-dependent inactivation of SR Ca2+ release channels and SR Ca2+ depletion are the two processes proposed to explain the decline of SR Ca2+ release during long-lasting depolarizations. However, the relative contribution of these processes, especially under physiological conditions of activation, is not clearly established. Using Fura-2 and Fluo-5N to monitor cytosolic and SR Ca2+ changes, respectively, in voltage-controlled mouse muscle fibers, we show that 2-min conditioning depolarizations reduce voltage-activated cytosolic Ca2+ signals with a V1/2 of −53 mV but also induce SR Ca2+ depletion that decreased the releasable pool of Ca2+ with the same voltage sensitivity. In contrast, measurement of SR Ca2+ changes indicated that SR Ca2+ release channels were inactivated after SR had been depleted and in response to much higher depolarizations with a V1/2 of −13 mV. In response to trains of action potentials, cytosolic Ca2+ signals decayed with time, whereas SR Ca2+ changes remained stable over 1-min stimulation, demonstrating that SR Ca2+ depletion is exclusively responsible for the decline of SR Ca2+ release under physiological conditions of excitation. These results suggest that previous studies using steady-state inactivation protocols to investigate the voltage dependence of Ca2+ release inactivation in fact probed the voltage dependence of SR Ca2+ depletion, and that SR Ca2+ depletion is the only process that leads to Ca2+ release decline during continuous stimulation of skeletal muscle.

scholarly journals Recordings of action potentials, charge movements, and sarcoplasmic reticulum Ca2+ release in isolated adult zebrafish fast skeletal muscle fibers reveals very fast kinetics of excitation–contraction coupling

2021 ◽  
Vol 154 (9) ◽  
Author(s):  
Romane Idoux ◽  
Christine Berthier ◽  
Vincent Jacquemond ◽  
Bruno Allard
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Action Potentials ◽  
Muscle Fibers ◽  
Fast Skeletal Muscle ◽  
Fast Kinetics ◽  
Ec Coupling ◽  
Skeletal Muscle Fibers ◽  
Charge Movements ◽  
Kinetics Of

The zebrafish has emerged as a very relevant animal model to decipher the pathophysiology of human muscle disorders. However, the vast majority of studies on zebrafish skeletal muscle have investigated genetic, histological, and molecular aspects, but functional approaches at the cellular level, especially in the field of excitation–contraction (EC) coupling, are scarcer and generally limited to cultured myotubes or fibers from embryonic zebrafish. Considering that zebrafish undergoes profound metamorphosis during transition from larval to adult stage and that number of muscle pathologies come up at ages far beyond embryonic stages, there is an actual need to investigate EC coupling in fully differentiated zebrafish skeletal muscle. In the present study, we were able to implement current and voltage clamp combined with intracellular Ca2+ measurements using the intracellularly loaded Ca2+ dye indo-1 in enzymatically isolated fast skeletal muscle fibers from 1-yr old zebrafish. Recording of action potentials (AP) in current-clamp conditions revealed very fast kinetics of the repolarization phase of AP. Measurements of intramembrane charge movements in voltage-clamp conditions showed that charge movement density was half that measured in mammalian fibers, but they displayed much faster kinetics. Ca2+ transients elicited by depolarization displayed a voltage-dependent phase of activation and voltage- and time-dependent phase of inactivation. Recording of Ca2+ signals elicited by trains of AP at different rates in current-clamp conditions indicated that Ca2+ signals fused at very high stimulation frequencies with no sign of Ca2+ signal decay for the entire 0.5 s duration of the stimulation, giving evidence that fibers were still able to generate AP and the sarcoplasmic reticulum to release Ca2+ with stimulation rates as high as 200 Hz. These data indicate that adult zebrafish fast skeletal muscle fibers exhibit strikingly fast kinetics of EC coupling from AP firing to charge movements and sarcoplasmic reticulum Ca2+ release.

scholarly journals Altering Skeletal Muscle EC Coupling by Ablating the Sarcoplasmic Reticulum Protein JP45 Affects Both Metabolism and Muscle Performance in Old Mice

2010 ◽  
Vol 98 (3) ◽  
pp. 547a
Author(s):  
Osvaldo Delbono ◽  
Zhong-Min Wang ◽  
Jackson Taylor ◽  
Maria Laura Messi ◽  
Susan Treves ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Muscle Performance ◽  
Ec Coupling ◽  
Old Mice

Chimeric calsequestrin and its targeting to the junctional sarcoplasmic reticulum of skeletal muscle

1997 ◽  
Vol 272 (5) ◽  
pp. C1420-C1428 ◽  
Author(s):  
A. Nori ◽  
K. A. Nadalini ◽  
A. Martini ◽  
R. Rizzuto ◽  
A. Villa ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Confocal Microscopy ◽  
Soleus Muscle ◽  
Hela Cells ◽  
Skeletal Muscles ◽  
Intracellular Localization ◽  
Primary Cultures ◽  
Muscle Fibers ◽  
Junctional Sarcoplasmic Reticulum

Calsequestrin (CS) is the junctional sarcoplasmic reticulum (jSR) Ca2+ binding protein responsible for intraluminal Ca2+ storage. The targeting mechanisms of CS to the jSR are yet to be unraveled. The nine-amino acid epitope of the influenza virus hemoagglutinin (referred to as HA1) was added at the COOH-terminal of CS by polymerase chain reaction cloning. The HA1-tagged CS cDNA was transiently transfected in either HeLa cells, myogenic cell lines, such as C2 and L8 cells, myoblasts of rat skeletal muscle primary cultures, or regenerating soleus muscle fibers of adult rats. The expression and intracellular localization of chimeric CS-HA1 were monitored by epifluorescence and confocal microscopy using either anti-CS antibodies or anti-HA1 antibodies. About 30% of transfected HeLa cells and 20-40% of myogenic cells expressed CS-HA1 into intracellular compartments, such as the perinuclear cisternae of endoplasmic reticulum (ER). Myoblasts of newborn rat skeletal muscles were first transfected and subsequently stimulated to differentiate into myotubes. CS-HA1 was detected in approximately 20% of transfected myotubes and did not affect CS distribution in myotubes. In the soleus muscle of adult rat, intramuscular injection of bupivacaine induced necrosis followed by regeneration. In vivo transfection of HA1-tagged CS cDNA in regenerating skeletal muscles determined expression in a few skeletal muscle fibers; CS-HA1 was localized only in jSR, as judged by confocal microscopy of longitudinal sections. The present results show that chimeric CS-HA1 is correctly sorted to ER/SR compartments and that the free COOH-terminal is not requested for sorting, retention, and segregation of CS to the SR.

Evidence for Na+/Ca2+exchange in intact single skeletal muscle fibers from the mouse

1998 ◽  
Vol 274 (4) ◽  
pp. C940-C946 ◽  
Author(s):  
Christopher D. Balnave ◽  
David G. Allen
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Muscle Fibers ◽  
Exchange Mechanism ◽  
Initial Exposure ◽  
Mouse Skeletal Muscle ◽  
Reverse Mode ◽  
Skeletal Muscle Fibers ◽  
Plateau Level ◽  
Sustained Increase

The myoplasmic free Ca2+concentration ([Ca2+]i) was measured in intact single fibers from mouse skeletal muscle with the fluorescent Ca2+ indicator indo 1. Some fibers were perfused in a solution in which the concentration of Na+ was reduced from 145.4 to 0.4 mM (low-Na+solution) in an attempt to activate reverse-mode Na+/Ca2+exchange (Ca2+ entry in exchange for Na+ leaving the cell). Under normal resting conditions, application of low-Na+ solution only increased [Ca2+]iby 5.8 ± 1.8 nM from a mean resting [Ca2+]iof 42 nM. In other fibers, [Ca2+]iwas elevated by stimulating sarcoplasmic reticulum (SR) Ca2+ release with caffeine (10 mM) and by inhibiting SR Ca2+ uptake with 2,5-di( tert-butyl)-1,4-benzohydroquinone (TBQ; 0.5 μM) in an attempt to activate forward-mode Na+/Ca2+exchange (Ca2+ removal from the cell in exchange for Na+ influx). These two agents caused a large increase in [Ca2+]i, which then declined to a plateau level approximately twice the baseline [Ca2+]iover 20 min. If the cell was allowed to recover between exposures to caffeine and TBQ in a solution in which Ca2+ had been removed, the increase in [Ca2+]iduring the second exposure was very low, suggesting that Ca2+ had left the cell during the initial exposure. Application of caffeine and TBQ to a preparation in low-Na+ solution produced a large, sustained increase in [Ca2+]iof ∼1 μM. However, when cells were exposed to caffeine and TBQ in a low-Na+ solution in which Ca2+ had been removed, a sustained increase in [Ca2+]iwas not observed, although [Ca2+]iremained higher and declined slower than in normal Na+ solution. This suggests that forward-mode Na+/Ca2+exchange contributed to the fall of [Ca2+]iin normal Na+ solution, but when extracellular Na+ was low, a prolonged elevation of [Ca2+]icould activate reverse-mode Na+/Ca2+exchange. The results provide evidence that skeletal muscle fibers possess a Na+/Ca2+exchange mechanism that becomes active in its forward mode when [Ca2+]iis increased to levels similar to that obtained during contraction.

Parvalbumin relaxes frog skeletal muscle when sarcoplasmic reticulum Ca(2+)-ATPase is inhibited

1996 ◽  
Vol 270 (2) ◽  
pp. C411-C417 ◽  
Author(s):  
Y. Jiang ◽  
J. D. Johnson ◽  
J. A. Rall
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Relaxation Rate ◽  
Time Course ◽  
Muscle Fibers ◽  
Peak Force ◽  
Half Time ◽  
Frog Skeletal Muscle ◽  
Twitch Force ◽  
Total Failure

Inhibition of sarcoplasmic reticulum (SR) Ca(2+)-adenosinetriphosphatase (ATPase) with 2,5-di-(tert-butyl)-1,4-benzohydroquinone (TBQ) in frog skeletal muscle fibers at 10 degrees C prolonged the half time of the fall of the Ca2+ transient by 62% and twitch force by 100% and increased peak force by 120% without increasing the amplitude of the Ca2+ signal. In the presence of TBQ the rate of relaxation and the rate of fall of Ca2+ became progressively slower in a series of twitches until relaxation failed. Relaxation rate decreased with a time course (approximately 2 s-1) similar to the Mg2+ off rate from purified parvalbumin (PA; 3.6 s-1). TBQ slowed the rate of fall of Ca2+ (5-fold) and force (8-fold) in a 0.3-s tetanus so that the rate of fall of Ca2+ (approximately 2.5 s-1) was similar to the Mg2+ off rate from PA. TBQ caused a near total failure of both Ca2+ sequestration and relaxation in a 1.1-s tetanus, during which PA would be saturated with Ca2+ and could not contribute to relaxation. Thus, when the SR Ca(2+)-ATPase is inhibited, Mg(2+)-PA can sequester Ca2+ and produce relaxation at a rate that is defined by the Mg2+ off rate from PA.

Sign in / Sign up

Export Citation Format

Share Document