The Impact of Magnesium on Isometric Twitch Parameters and Resting Membrane Potential of the Skeletal Muscle in Diabetic Rats

2012 ◽  
Vol 65 (3) ◽  
pp. 315-319 ◽  
Author(s):  
Aykut Pelit ◽  
Mustafa Emre ◽  
Kenan Dağli ◽  
Abdullah Tuli
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Diabetic Rats ◽  
Resting Membrane Potential ◽  
Isometric Twitch ◽  
The Impact

Effect of disuse on the resting membrane potential of skeletal muscle

1979 ◽  
Vol 64 (1) ◽  
pp. 231-234 ◽  
Author(s):  
Elis F. Stanley ◽  
Daniel B. Drachman
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Resting Membrane Potential

Development of membrane conductance of chick skeletal muscle in culture

1980 ◽  
Vol 58 (6) ◽  
pp. 600-605 ◽  
Author(s):  
C. M. Thomson ◽  
W. F. Dryden
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Initial Level ◽  
Potassium Conductance ◽  
Membrane Conductance ◽  
Resting Membrane Potential ◽  
Membrane Conductances ◽  
Rapid Changes ◽  
Fibre Development

Resting membrane potentials and membrane conductances of chick skeletal muscle in culture were determined from the 3rd to the 10th day after plating. The effect of tetraethylammonium (TEA) and of replacement of potassium with caesium on these parameters was investigated. Resting membrane potential (Em) rises during myogenesis in vitro and resting membrane conductance (Gm) falls. The initial level of Gm was relatively high (1.2 mS cm−2) but this fell to a final level around 0.2 mS cm−2. The most rapid changes in both parameters occurred between days 3 and 5 of culture. Both TEA and caesium depressed Em and Gm at all stages of development. On the 3rd day of culture Gm was reduced by 0.2 mS cm−2 by both agents. Thereafter, Gm was depressed by about 0.1 mS cm−2. Caesium does not penetrate potassium channels and the reduction in Gm is attributed to block of these channels. This indicates that resting potassium conductance is relatively constant at 0.1 mS cm−2 throughout muscle fibre development. Because TEA produces changes in Gm similar to those produced by caesium, TEA is concluded to be acting at the potassium channel in a manner similar to caesium.

scholarly journals Human Myoblast Fusion Requires Expression of Functional Inward Rectifier Kir2.1 Channels

2001 ◽  
Vol 153 (4) ◽  
pp. 677-686 ◽  
Author(s):  
Jacqueline Fischer-Lougheed ◽  
Jian-Hui Liu ◽  
Estelle Espinos ◽  
David Mordasini ◽  
Charles R. Bader ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Muscle Development ◽  
Myoblast Fusion ◽  
Inward Rectifier ◽  
Resting Membrane Potential ◽  
Skeletal Muscle Development ◽  
K Channels ◽  
Window Current ◽  
Human Myoblast

Myoblast fusion is essential to skeletal muscle development and repair. We have demonstrated previously that human myoblasts hyperpolarize, before fusion, through the sequential expression of two K+ channels: an ether-à-go-go and an inward rectifier. This hyperpolarization is a prerequisite for fusion, as it sets the resting membrane potential in a range at which Ca2+ can enter myoblasts and thereby trigger fusion via a window current through α1H T channels.

Glutamine transport and metabolism in denervated rat skeletal muscle

1990 ◽  
Vol 259 (2) ◽  
pp. E148-E154 ◽  
Author(s):  
H. S. Hundal ◽  
P. Babij ◽  
P. W. Watt ◽  
M. R. Ward ◽  
M. J. Rennie
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Maximal Activity ◽  
Resting Membrane Potential ◽  
Na Channel ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Rat Skeletal Muscle ◽  
Glutamine Transport ◽  
Recovery Of Vmax

Rat skeletal muscle glutamine fell by 40% from 4.18 to 2.5 mumols/g wet weight (P less than 0.01) after 4 days of denervation. Over the same period net glutamine efflux from denervated hindlimbs [i.e., arteriovenous (a-v) concentration differences x blood flow] increased 3.5-fold (from -6.72 +/- 1.73 to -26 +/- 4.81 nmol.min-1.g-1, P less than 0.001). Gastrocnemius glutamine synthetase activity fell 48% after denervation (from 475 +/- 81 to 248 +/- 39 nmol.min-1.g-1, P less than 0.001), but glutaminase activity was not significantly altered (17 nmol.min-1.g-1). The maximal activity (Vmax) of the unidirectional Na(+)-dependent glutamine transporter (system Nm) was depressed by 45% from 1,020 +/- 104 to 571 +/- 9 nmol.min-1.g-1 (P less than 0.01), but the concentration at which transport was half maximal (Km) was not significantly altered (control 8.1 +/- 0.6 mM; denervated 6.52 +/- 0.12). Hindlimb denervation resulted in an increase of intramuscular Na+ by 17% and a fall of K+ by 12%, and the resting membrane potential in isolated muscles decreased from -75 +/- 10 to -59.5 +/- 5.5 mV. Membrane potential of perfused denervated muscle, isolated after acute addition of the Na+ channel blocker tetrodotoxin (TTX, 3 microM), repolarized to -66.4 +/- 3.2 mV. In perfused denervated preparations TTX caused an acute recovery of Vmax of unidirectional glutamine transport to 848 +/- 75 nmol.min-1.g-1; Km was unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of aging on sarcoplasmic reticulum function and contraction duration in skeletal muscles of the rat

1996 ◽  
Vol 271 (4) ◽  
pp. C1032-C1040 ◽  
Author(s):  
N. Narayanan ◽  
D. L. Jones ◽  
A. Xu ◽  
J. C. Yu
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Soleus Muscle ◽  
Pump Function ◽  
Related Difference ◽  
Contraction Duration ◽  
Age Related ◽  
Isometric Twitch ◽  
Effects Of Aging ◽  
The Impact

The impact of aging on the Ca2+ pump function of skeletal muscle sarcoplasmic reticulum (SR) was investigated using SR-enriched membrane vesicles isolated from the slow-twitch soleus muscle (SM) and the relatively fast-twitch gastrocnemius muscle (GM) isolated from adult (6-8 mo old) and aged (26-28 mo old) Fischer 344 rats. In addition, isometric twitch characteristics of SM and GM were determined in situ in adult and aged rats under anesthesia. The rates of ATP-supported Ca2+ uptake by SM SR was markedly lower ( approximately 50%) in the aged compared with adult at varying Ca2+ (0.11-8.24 microM) concentrations. Kinetic analysis of the data revealed age-associated decrease in maximum activity reached (Vmax) and increase in the concentration of Ca2+ giving half of Vmax. In contrast, no significant age-related difference was observed in ATP-supported Ca2+ uptake activity of GM SR. The Ca(2+)-stimulated adenosinetriphosphatase (ATPase) activities and the amount of Ca(2+)-ATPase protein did not vary significantly with aging in SM or GM SR. Also, no significant age-related difference was observed in the content of the ryanodine receptor (Ca(2+)-release channel) or the Ca2+ binding protein, calsequestrin in SM and GM SR. In isometrically contracting SM, the time to peak force, half-relaxation time, and contraction duration were significantly prolonged in the aged compared with adult, whereas there was no age-related difference in maximum developed force. None of these isometric twitch parameters differed significantly with age in the GM. These results demonstrate that the effects of aging on skeletal muscle contractile properties and SR function are muscle specific. Furthermore, the data strongly suggest that impairment in SR Ca2+ pump function, apparently due to uncoupling of ATP hydrolysis from Ca2+ transport, contributes to the age-associated slowing of relaxation in the soleus muscle.

scholarly journals Spatially resolved changes in diabetic rat skeletal muscle metabolism in vivo studied by 31P-n.m.r. spectroscopy

1990 ◽  
Vol 268 (1) ◽  
pp. 111-115 ◽  
Author(s):  
R A J Challiss ◽  
M J Blackledge ◽  
G K Radda
Keyword(s):  
Skeletal Muscle ◽  
Muscle Metabolism ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Metabolic Dysfunction ◽  
Spatially Resolved ◽  
Phosphorus Containing ◽  
Stimulation Period ◽  
Isometric Twitch

Phase-modulated rotating-frame imaging (p.m.r.f.i.), a localization technique for 31P-n.m.r. spectroscopy, has been applied to obtain information on the heterogeneity of phosphorus-containing metabolites and pH in the skeletal muscle of control and streptozotocin-diabetic rats. Using this method, the metabolic changes in four spatially resolved longitudinal slices (where slice I is superficial and slice IV is deep muscle) through the ankle flexor muscles have been investigated at rest and during steady-state isometric twitch-contraction at 2 Hz. At rest, intracellular pH was lower, and phosphocreatine (PCr)/ATP was higher, throughout the muscle mass in diabetic compared with control animals. The change in PCr/ATP in diabetic muscle correlated with a decrease in the chemically determined ATP concentration. During the muscle stimulation period, the decrease in pH observed in diabetic muscle at rest was maintained, but not exacerbated, by the contractile stimulus. Stimulation of muscle contraction caused more marked changes in PCr/(PCr + Pi), PCr/ATP and Pi/ATP in the diabetic group. These changes were most evident in slice III, which contains the greatest proportion of fast glycolytic-oxidative (type IIa) fibres, in which statistically significant differences were observed for all metabolite ratios. The results presented suggest that some degree of heterogeneity occurs in diabetic skeletal muscle in vivo with respect to the extent of metabolic dysfunction caused by the diabetic insult and that regions of the muscle containing high proportions of type IIa fibres appear to be most severely affected.

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