scholarly journals Sarcoplasmic Reticulum Ca2+ Content Affects 4-CmC and Caffeine Contractures of Rat Skinned Skeletal Muscle Fibers.

2001 ◽  
Vol 51 (6) ◽  
pp. 661-669 ◽  
Author(s):  
Stéphanie Choisy ◽  
Alexandra Divet ◽  
Corinne Huchet-Cadiou ◽  
Claude Léoty
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Muscle Fibers ◽  
Skeletal Muscle Fibers ◽  
Caffeine Contractures

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.

scholarly journals Effects of Cannabinoids on Caffeine Contractures in Slow and Fast Skeletal Muscle Fibers of the Frog

2009 ◽  
Vol 229 (2) ◽  
pp. 91-99 ◽  
Author(s):  
Miguel Huerta ◽  
Mónica Ortiz-Mesina ◽  
Xóchitl Trujillo ◽  
Enrique Sánchez-Pastor ◽  
Clemente Vásquez ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Fast Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Caffeine Contractures

scholarly journals Calcium-gated calcium channels in sarcoplasmic reticulum of rabbit skinned skeletal muscle fibers.

1986 ◽  
Vol 87 (2) ◽  
pp. 289-303 ◽  
Author(s):  
P Volpe ◽  
G Salviati ◽  
A Chu
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Isometric Force ◽  
Muscle Fibers ◽  
Ruthenium Red ◽  
Scattering Method ◽  
Tension Development ◽  
Maximal Force ◽  
Skeletal Muscle Fibers ◽  
Ca2 Channels

The action of ruthenium red (RR) on Ca2+ loading by and Ca2+ release from the sarcoplasmic reticulum (SR) of chemically skinned skeletal muscle fibers of the rabbit was investigated. Ca2+ loading, in the presence of the precipitating anion pyrophosphate, was monitored by a light-scattering method. Ca2+ release was indirectly measured by following tension development evoked by caffeine. Stimulation of the Ca2+ loading rate by 5 microM RR was dependent on free Ca2+, being maximal at pCa 5.56. Isometric force development induced by 5 mM caffeine was reversibly antagonized by RR. IC50 for the rate of tension rise was 0.5 microM; that for the extent of tension was 4 microM. RR slightly shifted the steady state isometric force/pCa curve toward lower pCa values. At 5 microM RR, the pCa required for half-maximal force was 0.2 log units lower than that of the control, and maximal force was depressed by approximately 16%. These results suggest that RR inhibited Ca2+ release from the SR and stimulated Ca2+ loading into the SR by closing Ca2+-gated Ca2+ channels. Previous studies on isolated SR have indicated the selective presence of such channels in junctional terminal cisternae.

Differential Effects of Sevoflurane, Isoflurane, and Halothane on Ca (2+) Release from the Sarcoplasmic Reticulum of Skeletal Muscle 

1999 ◽  
Vol 91 (1) ◽  
pp. 179-186 ◽  
Author(s):  
Gudrun Kunst ◽  
Bernhard M. Graf ◽  
Rupert Schreiner ◽  
Eike Martin ◽  
Rainer H. A. Fink
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Muscle Fibers ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Maximal Force ◽  
Skinned Muscle ◽  
Skeletal Muscle Fibers ◽  
Force Relation ◽  
The Individual

Background Although malignant hyperthermia after application of sevoflurane has been reported, little is known about its action on intracellular calcium homeostasis of skeletal muscle. The authors compared the effect of sevoflurane with that of isoflurane and halothane on Ca2+ release of mammalian sarcoplasmic reticulum and applied a novel method to quantify Ca2+ turnover in permeabilized skeletal muscle fibers. Methods Liquid sevoflurane, isoflurane, and halothane at 0.6 mM, 3.5 mM, and 7.6 mm were diluted either in weakly calcium buffered solutions with no added Ca2+ (to monitor Ca2+ release) or in strongly Ca2+ buffered solutions with [Ca2+] values between 3 nM and 24.9 microm for [Ca+]-force relations. Measurements were taken on single saponin skinned muscle fiber preparations of BALB/c mice. Individual [Ca2+]force relations were characterized by the Ca2+ concentration at half-maximal force that indicates the sensitivity of the contractile proteins and by the steepness. Each force transient was transformed directly into a Ca2+ transient with respect to the individual [Ca2+]-force relation of the fiber. Results At 0.6 mM, single force transients induced by sevoflurane were lower compared with equimolar concentrations of isoflurane and halothane (P < 0.05). Similarly, calculated peak Ca2+ transients of sevoflurane were lower than those induced by equimolar halothane (P < 0.05). The Ca2+ concentrations at half maximal force were decreased after the addition of sevoflurane, isoflurane, and halothane in a concentration-dependent manner (P < 0.05). Conclusion Whereas sevoflurane, isoflurane, and halothane similarly increase the Ca2+ sensitivity of the contractile apparatus in skeletal muscle fibers, 0.6 mM sevoflurane induces smaller Ca2+ releases from the sarcoplasmic reticulum than does equimolar halothane.

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