scholarly journals Time course analysis of the methylprednisolone (MePred)-regulated transcriptomine in rat skeletal muscle

2015 ◽  
Author(s):  
R Almon
Keyword(s):  
Skeletal Muscle ◽  
Time Course ◽  
Rat Skeletal Muscle

Vitamin E Concentration in Rat Skeletal Muscle and Liver after Exercise

1998 ◽  
Vol 8 (2) ◽  
pp. 105-112 ◽  
Author(s):  
Jon N. Swift ◽  
James P. Kehrer ◽  
K. Stephen Seiler ◽  
Joseph W. Starnes
Keyword(s):  
Skeletal Muscle ◽  
Vitamin E ◽  
High Performance ◽  
Time Course ◽  
Vastus Lateralis ◽  
Sprague Dawley ◽  
Rat Skeletal Muscle ◽  
Sedentary Control ◽  
Sprague Dawley Rats ◽  
Response To Exercise

The purpose of this study was to determine whether submaximal exercise significantly changes the concentration of vitamin E (αToc) in rat liver and skeletal muscle and to establish a time course for the return to basal levels. Male Sprague-Dawley rats, age 8 to 10 weeks, were randomly divided into sedentary control (Con) (n = 7) and exercise n = 17) groups. Exercised animals ran 100 min on a motorized treadmill at approximately 70% VO2max for 3 consecutive days. They were then sacrificed immediately postexercise (0Post), 24 hr post (24Post), or 72 hr post (72Post). The gastrocnemius, red vastus lateralis (RV), white vastus lateralis (WV), and liver were excised and analyzed for αToc concentration by high-performance liquid chromolography utilizing electrochemical detection. We found that after 3 consecutive days of exercise, αToc was reduced in RV and WV at 0Post and 24Post but returned to control values by 72Post. Liver αToc content was not changed at OPost but was significantly reduced at 24 Post and 72 Post. No significant changes in αToc were observed in the gastrocnemius in response to exercise. The data indicate that following an exercise-related decrease, skeletal muscle vitamin E concentration requires more than 24 hr to return to the preexercise concentration, and that the replenishment process may involve redistribution of vitamin E from liver to muscle.

Mechanism of insulin action on glucose transport in rat skeletal muscle

1988 ◽  
Vol 254 (5) ◽  
pp. E633-E638 ◽  
Author(s):  
E. Sternlicht ◽  
R. J. Barnard ◽  
G. K. Grimditch
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Binding Sites ◽  
Time Course ◽  
Cytochalasin B ◽  
Early Time ◽  
Insulin Injection ◽  
Insulin Stimulation ◽  
Rat Skeletal Muscle ◽  
Transport Molecules

This study was designed to examine the effect of insulin stimulation on glucose transport in rat skeletal muscle. Sarcolemmal vesicles (SL) were isolated from the gastrocnemius-plantaris and quadriceps muscles from insulin-stimulated and control groups. The insulin-stimulated group received an intravenous insulin injection (1 U/kg) 10 min before isolation. The early time course of specific D-glucose transport was linear through 2 s. Michaelis-Menten kinetics at 1.5 s indicated that the Vmax for glucose transport was increased after insulin stimulation compared with controls (4,424 +/- 668 vs. 1,366 +/- 124 pmol.mg protein -1.s-1), whereas the Km remained unchanged (19.4 +/- 0.6 vs. 21.6 +/- 3.1 mM). Scatchard plots for the D-glucose-inhibitable class of cytochalasin B binding sites indicated that insulin stimulation increased the number of binding sites in the SL vesicles (9.3 +/- 0.6 vs. 5.5 +/- 0.3 pmol/mg protein) without altering the Kd (48 +/- 3 vs. 46 +/- 3 nM). That the increase in Vmax was greater than the increase in cytochalasin B binding sites indicates that insulin stimulation caused an increase in the turnover rate of existing transport molecules as well as an increase in the total number of SL glucose transport molecules.

scholarly journals A quantitative study of potassium channel kinetics in rat skeletal muscle from 1 to 37 degrees C.

1983 ◽  
Vol 81 (4) ◽  
pp. 485-512 ◽  
Author(s):  
K G Beam ◽  
P L Donaldson
Keyword(s):  
Skeletal Muscle ◽  
Low Temperatures ◽  
Time Course ◽  
Voltage Dependence ◽  
Potassium Currents ◽  
Effect Of Temperature ◽  
Time Axis ◽  
Rat Skeletal Muscle ◽  
Rapid Phase ◽  
Qualitative Effect

Potassium currents were measured using the three-microelectrode voltage-clamp technique in rat omohyoid muscle at temperatures from 1 to 37 degrees C. The currents were fitted according to the Hodgkin-Huxley equations as modified for K currents in frog skeletal muscle (Adrian et al., 1970a). The equations provided an approximate description of the time course of activation, the voltage dependence of the time constant of activation (tau n), and the voltage dependence of gK infinity. At higher temperatures the relationship between gK infinity and voltage was shifted in the hyperpolarizing direction. The effect of temperature on tau n was much greater in the cold than in the warm: tau n had a Q10 of nearly 6 at temperatures below 10 degrees C, but a Q10 of only approximately 2 over the range of 30-38 degrees C. The decreasing dependence of tau n on temperature was gradual and the Arrhenius plot of tau n revealed no obvious break-points. In addition to its quantitative effect on activation kinetics, temperature also had a qualitative effect. Near physiological temperatures (above approximately 25 degrees C), the current was well described by n4 kinetics. At intermediate temperatures (approximately 15-25 degrees C), the current was well described by n4 kinetics, but only if the n4 curve was translated rightward along the time axis (i.e., the current had a greater delay than could be accounted for by simple n4 kinetics). At low temperatures (below approximately 15 degrees C), n4 kinetics provided only an approximate fit whether or not the theoretical curve was translated along the time axis. In particular, currents in the cold displayed an initial rapid phase of activation followed by a much slower one. Thus, low temperatures appear to reveal steps in the gating process which are kinetically "hidden" at higher temperatures. Taken together, the effects of temperature on potassium currents in rat skeletal muscle demonstrate that the behavior of potassium channels at physiological temperatures cannot be extrapolated, either quantitatively or qualitatively, from experiments carried out in the cold.

Fiber-specific regulation of Ca(2+)-ATPase isoform expression by thyroid hormone in rat skeletal muscle

1996 ◽  
Vol 271 (6) ◽  
pp. C1908-C1919 ◽  
Author(s):  
C. G. van der Linden ◽  
W. S. Simonides ◽  
A. Muller ◽  
W. J. van der Laarse ◽  
J. L. Vermeulen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Thyroid Hormone ◽  
Atpase Activity ◽  
Cross Sections ◽  
Time Course ◽  
Myosin Heavy Chain Isoforms ◽  
Rat Skeletal Muscle ◽  
Mhc I ◽  
Isoform Expression ◽  
Specific Regulation

We studied the effect of thyroid hormone (3,5,3'-triiodo-L-thyronine, T3) on the expression of sarcoplasmic reticulum (SR) fast- and slow-type Ca(2+)-ATPase isoforms, SERCA1 and SERCA2a, respectively, and total SR Ca(2+)-ATPase activity in rat skeletal muscle. Cross sections and homogenates of soleus and extensor digitorum longus muscles from hypo-, eu-, and hyperthyroid rats were examined, and expression of Ca(2+)-ATPase isoforms in individual fibers was compared with expression of fast (MHC II) and slow (MHC I) myosin heavy chain isoforms. In both muscles, T3 induced a coordinated and full conversion to a fast-twitch phenotype in one-half of the fibers that were slow twitch in the absence of T3. The conversion was partial in the other one-half of the fibers, giving rise to a mixed phenotype. The stimulation by T3 of total SERCA expression in all fibers was reflected by increased SR Ca(2+)-ATPase activity. The time course of the T3-induced changes of SERCA isoform expression was examined 1-14 days after the start of daily T3 treatment of euthyroid rats. SERCA1 expression was stimulated by T3 at a pretranslational level in all fibers. SERCA2a mRNA expression was transiently stimulated and disappeared in a subset of fibers. In these fibers SR Ca(2+)-ATPase activity was high because of high SERCA1 protein levels. These data suggest that the ultimate downregulation of SERCA2a expression, which is always associated with high SR Ca(2+)-ATPase activities, occurs at a pretranslational level.

scholarly journals Rapid Reversal of Insulin-Stimulated AS160 Phosphorylation in Rat Skeletal Muscle after Insulin Exposure

2010 ◽  
pp. 71-78
Author(s):  
N Sharma ◽  
E B Arias ◽  
G D Cartee
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Time Course ◽  
Half Time ◽  
Rat Skeletal Muscle ◽  
Akt Phosphorylation ◽  
Rapid Reversal ◽  
Time Courses

Increased phosphorylation of Akt substrate of 160 kDa (AS160) is essential to trigger the full increase in insulin-stimulated glucose transport in skeletal muscle. The primary aim of this study was to characterize the time course for reversal of insulin-stimulated AS160 phosphorylation in rat skeletal muscle after insulin removal. The time courses for reversal of insulin effects both upstream (Akt phosphorylation) and downstream (glucose uptake) of AS160 were also determined. Epitrochlearis muscles were incubated in vitro using three protocols which differed with regard to insulin exposure: No Insulin (never exposed to insulin), Transient Insulin (30 min with 1.8 nmol/l insulin, then incubation without insulin for 10, 20 or 40 min), or Sustained Insulin (continuously incubated with 1.8 nmol/l insulin). After removal of muscles from insulin, Akt and AS160 phosphorylation reversed rapidly, each with a half-time of <10 min and essentially full reversal by 20 min. Glucose uptake reversed more slowly (half time between 10 and 20 min with essentially full reversal by 40 min). Removal of muscles from insulin resulted in a rapid reversal of the increase in AS160 phosphorylation which preceded the reversal of the increase in glucose uptake, consistent with AS160 phosphorylation being essential for maintenance of insulin-stimulated glucose uptake.

scholarly journals Lactate transport activity in rat skeletal muscle sarcolemmal vesicles after acute exhaustive exercise

1999 ◽  
Vol 87 (3) ◽  
pp. 955-961 ◽  
Author(s):  
H. Dubouchaud ◽  
N. Eydoux ◽  
P. Granier ◽  
C. Préfaut ◽  
J. Mercier
Keyword(s):  
Skeletal Muscle ◽  
Time Course ◽  
Lactate Concentration ◽  
Treadmill Running ◽  
Exhaustive Exercise ◽  
Transport Activity ◽  
Rat Skeletal Muscle ◽  
Lactate Transport ◽  
Single Bout ◽  
Lactate Uptake

The effect of a single bout of exhaustive exercise on muscle lactate transport capacity was studied in rat skeletal muscle sarcolemmal (SL) vesicles. Rats were assigned to a control (C) group ( n = 14) or an acutely exercised (E) group ( n = 20). Exercise consisted of treadmill running (25 m/min, 10% grade) to exhaustion. SL vesicles purified from C and E rats were sealed because of sensitivity to osmotic forces. The time course of 1 mM lactate uptake in zero- trans conditions showed that the equilibrium level in the E group was significantly lower than in the C group ( P < 0.05). The initial rate of 1 mM lactate uptake decreased significantly from 2.44 ± 0.22 to 1.03 ± 0.08 nmol ⋅ min−1 ⋅ mg protein−1( P < 0.05) after exercise, whereas that of 50 mM lactate uptake did not differ significantly between the two groups. For 100 mM external lactate concentration ([lactate]), exhaustive exercise increased initial rates of lactate uptake (219.6 ± 36.3 to 465.4 ± 80.2 nmol ⋅ min−1 ⋅ mg protein−1, P < 0.05). Although saturation kinetics were observed in the C group with a maximal transport velocity of 233 nmol ⋅ min−1 ⋅ mg protein−1 and a Michealis-Menten constant of 24.5 mM, saturation properties were not seen after exhaustive exercise in the E group, because initial rates of lactate uptake increased linearly with external [lactate]. We conclude that a single bout of exhaustive exercise significantly modified SL lactate transport activity, resulting in a decrease in 1 mM lactate uptake and was associated with alterations in the saturable properties at [lactate] above 50 mM. These results suggest that changes in sarcolemmal lactate transport activity may alter lactate and proton exchanges after exhaustive exercise.

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