Effects of Reactive Oxygen Species on Aspects of Excitation-Contraction Coupling in Chemically Skinned Rabbit Diaphragm Muscle Fibres

2001 ◽  
Vol 86 (2) ◽  
pp. 161-168 ◽  
Author(s):  
G. M. Darnley ◽  
A. M. Duke ◽  
D. S. Steele ◽  
N. G. MacFarlane
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Diaphragm Muscle ◽  
Muscle Fibres ◽  
Oxygen Species ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling

Effect of reactive oxygen species on K+ contractures in the rat diaphragm

1998 ◽  
Vol 84 (3) ◽  
pp. 948-953 ◽  
Author(s):  
John M. Lawler ◽  
Z. Hu ◽  
W. S. Barnes
Keyword(s):  
Reactive Oxygen Species ◽  
Xanthine Oxidase ◽  
Reactive Oxygen ◽  
Fiber Bundles ◽  
Oxygen Species ◽  
Rat Diaphragm ◽  
Membrane Excitability ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling

Reactive oxygen species (ROS) are postulated to alter low-frequency contractility of the unfatigued and fatigued diaphragm. It has been proposed that ROS affect contractility through changes in membrane excitability and excitation-contraction coupling. If this hypothesis is true, then ROS should alter depolarization-dependent K+contractures. Xanthine oxidase (0.01 U/ml) + hypoxanthine (1 mM) were used as a source of superoxide anion eliciting oxidative stress on diaphragm fiber bundles in vitro. Diaphragm fiber bundles from 4-mo-old Fischer 344 rats were extracted and immediately placed in Krebs solution bubbled with 95% O2-5% CO2. After 10 min of equilibration, a K+ contracture (Pre; 135 mM KCl) was induced. Fiber bundles were assigned to the following treatment groups: normal Krebs-Ringer (KR; Con) and the xanthine oxidase system (XO) in KR solution. After 15 min of treatment exposure, a second (Post) K+contracture was elicited. Mean time-to-peak tension for contractures was significantly decreased in Post vs. Pre (16.0 ± 0.7 vs. 19.8 ± 1.0 s) with XO; no change was noted with Con. Furthermore, peak contracture tension was significantly higher (31.5%) in the XO group Post compared with Pre; again, no significant change was found with KR. The relaxation phase was also altered with XO but not with KR. Additional experiments were conducted with application of 1 mM hypoxanthine, with results similar to the Con group. We conclude that the application of ROS altered the dynamics of K+ contractures in the rat diaphragm, indicating changes in voltage-dependent excitation-contraction coupling.

O08 Reactive oxygen species and loss of muscle fibres during ageing

2010 ◽  
Vol 20 ◽  
pp. S3
Author(s):  
M.J. Jackson ◽  
T. Pearson ◽  
A. Vasilaki ◽  
G. Sakellariou ◽  
J. Palomero ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Muscle Fibres ◽  
Oxygen Species

Formation of reactive oxygen species by the contracting diaphragm is PLA2dependent

1999 ◽  
Vol 87 (2) ◽  
pp. 792-800 ◽  
Author(s):  
D. Nethery ◽  
D. Stofan ◽  
L. Callahan ◽  
A. DiMarco ◽  
G. Supinski
Keyword(s):  
Reactive Oxygen Species ◽  
Aristolochic Acid ◽  
Reactive Oxygen ◽  
Diaphragm Muscle ◽  
Ros Generation ◽  
Complete Suppression ◽  
Organ Bath ◽  
Oxygen Species ◽  
Ros Formation

Recent work indicates that respiratory muscles generate superoxide radicals during contraction (M. B. Reid, K. E. Haack, K. M. Francik, P. A. Volberg, L. Kabzik, and M. S. West. J. Appl. Physiol. 73: 1797–1804, 1992). The intracellular pathways involved in this process are, however, unknown. The purpose of the present study was to test the hypothesis that contraction-related formation of reactive oxygen species (ROS) by skeletal muscle is linked to activation of the 14-kDa isoform of phospholipase A2(PLA2). Studies were performed by using an in vitro hemidiaphragm preparation submerged in an organ bath, and formation of ROS in muscles was assessed by using a recently described fluorescent indicator technique. We examined ROS formation in resting and contracting muscle preparations and then determined whether contraction-related ROS generation could be altered by administration of various PLA2 inhibitors: manoalide and aristolochic acid, both inhibitors of 14-kDa PLA2; arachidonyltrifluoromethyl ketone (AACOCF3), an inhibitor of 85-kDa PLA2; and haloenol lactone suicide substrate (HELSS), an inhibitor of calcium-independent PLA2. We found 1) little ROS formation [2.0 ± 0.8 (SE) ng/mg] in noncontracting control diaphragms, 2) a high level of ROS (20.0 ± 2.0 ng/mg) in electrically stimulated contracting diaphragms (trains of 20-Hz stimuli for 10 min, train rate 0.25 s−1), 3) near-complete suppression of ROS generation in manoalide (3.0 ± 0.5 ng/mg, P < 0.001)- and aristolochic acid-treated contracting diaphragms (4.0 ± 1.0 ng/mg, P < 0.001), and 4) no effect of AACOCF3 or HELSS on ROS formation in contracting diaphragm. During in vitro studies examining fluorescent measurement of ROS formation in response to a hypoxanthine/xanthine oxidase superoxide-generating solution, manoalide, aristolochic acid, AACOCF3, and HELSS had no effect on signal intensity. These data indicate that ROS formation by contracting diaphragm muscle can be suppressed by the administration of inhibitors of the 14-kDa isoform of PLA2 and suggest that this enzyme plays a critical role in modulating ROS formation during muscle contraction.

scholarly journals Intra- and extracellular measurement of reactive oxygen species produced during heat stress in diaphragm muscle

2000 ◽  
Vol 279 (4) ◽  
pp. C1058-C1066 ◽  
Author(s):  
Li Zuo ◽  
Fievos L. Christofi ◽  
Valerie P. Wright ◽  
Cynthia Yu Liu ◽  
A. John Merola ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Heat Stress ◽  
Cytochrome C ◽  
Reactive Oxygen ◽  
Diaphragm Muscle ◽  
Oxygen Species ◽  
Intracellular Ros ◽  
Ros Formation ◽  
Severe Exercise ◽  
Environmental Temperatures

Skeletal muscles are exposed to increased temperatures during intense exercise, particularly in high environmental temperatures. We hypothesized that heat may directly stimulate the reactive oxygen species (ROS) formation in diaphragm (one kind of skeletal muscle) and thus potentially play a role in contractile and metabolic activity. Laser scan confocal microscopy was used to study the conversion of hydroethidine (a probe for intracellular ROS) to ethidium (ET) in mouse diaphragm. During a 30-min period, heat (42°C) increased ET fluorescence by 24 ± 4%, whereas in control (37°C), fluorescence decreased by 8 ± 1% compared with baseline ( P < 0.001). The superoxide scavenger Tiron (10 mM) abolished the rise in intracellular fluorescence, whereas extracellular superoxide dismutase (SOD; 5,000 U/ml) had no significant effect. Reduction of oxidized cytochrome c was used to detect extracellular ROS in rat diaphragm. After 45 min, 53 ± 7 nmol cytochrome c · g dry wt−1 · ml−1 were reduced in heat compared with 22 ± 13 nmol · g−1 · ml−1 in controls ( P < 0.001). SOD decreased cytochrome creduction in heat to control levels. The results suggest that heat stress stimulates intracellular and extracellular superoxide production, which may contribute to the physiological responses to severe exercise or the pathology of heat shock.

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