scholarly journals Alteration of sarcoplasmic reticulum after denervation of chicken pectoralis muscle

1983 ◽  
Vol 210 (2) ◽  
pp. 339-344 ◽  
Author(s):  
C A Tate ◽  
R J Bick ◽  
T D Myers ◽  
B J R Pitts ◽  
W B Van Winkle ◽  
...  

To determine the neural influence on the function of the sarcoplasmic reticulum (SR) of fast-twitch skeletal muscle, the superior pectoralis muscle of adult chicken was denervated, and the SR was isolated at 20 days post-denervation. The isolated SR was probably derived from the longitudinal SR and was relatively free of contaminants. The protein profile of the SR was quantitatively changed after denervation with an increase in the M55 and 30000-mol.wt. proteins relative to the Ca2+-ATPase. Ca2+-dependent ATPase activity and phosphoenzyme formation were lower in the denervated-muscle SR; however, the enzyme catalytic-centre activity was similar to the control value. The decrease in Ca2+-ATPase activity in denervated-muscle SR was accompanied by a lower Ca2+ accumulation so that the relationship between Ca2+ accumulation and Ca2+-dependent ATPase activity was well maintained in the SR from denervated muscle. The data imply that denervation may result in a diminution of functional Ca2+ pump sites. Evidence is presented, though, which suggests that denervation affects a single class of Ca2+-binding sites of the Ca2+-ATPase, resulting in a lower affinity for Ca2+.

1985 ◽  
Vol 40 (9-10) ◽  
pp. 726-734 ◽  
Author(s):  
Maria Tereza Nunes ◽  
Antonio Carlos Bianco

Abstract The properties of the sarcoplasmic reticulum membranes isolated from slow-twitch type I soleus and fast-twitch type II psoas muscles of control and thyroxine treated rabbits were comparatively studied. Membrane yield, maximal calcium storing capacity, ATP-supported calcium uptake, calcium-dependent ATPase activity and calcium-dependent phosphoprotein formation were found to be 3-10 fold higher in psoas than in soleus preparations. Membrane yield, calcium-dependent ATPase activity, ATP-supported calcium transport and calcium-dependent phospho­ protein are at least twice enhanced in the membranes from soleus muscles of animals treated for 14-21 days with thyroxine. The corresponding capacities of the membranes from psoas muscles are not further augmented by the same thyroxine treatment. The maximal calcium storing capaci­ ty of the psoas membranes is their sole specific property which is significantly increased. The changes in the properties of the soleus muscles’ sarcoplasmic reticulum membranes are engen­dered by an increase from 5 to 30-50% in the number of type II fibres. Since the calcium transporting properties of the sarcoplasmic reticulum membranes from type II fibres qualitatively differ from those of type I fibres, thyroxine does not only affect quantitative but also qualitative parameters of the muscles’ sarcoplasmic reticulum membrane system.


1998 ◽  
Vol 853 (1 CARDIAC SARCO) ◽  
pp. 333-337 ◽  
Author(s):  
ION I. MORARU ◽  
SERGEI SYRBU ◽  
NADA ZECEVIC ◽  
DAVID W. HAGER ◽  
JAMES WATRAS ◽  
...  

1983 ◽  
Vol 38 (9-10) ◽  
pp. 834-844 ◽  
Author(s):  
Gertrude Swoboda ◽  
Wilhelm Hasselbach

In the reaction of sarcoplasmic reticulum m em branes with excess 5,5′-dithiobis(2-nitrobenzoate) (DTNB) some new features were observed:1) The Ca2+-dependent ATPase activities of increasingly modified preparations were considerably enhanced during the initial stage of thiol blockage. A maximum (130 -160% of the control activity) was reached when about 1.5 - 2 mol thiol groups per 105 g vesicular protein had reacted, in the absence of ATP and detergent. At higher extents of modification inactivation occurred. Purified ATPase behaved principally similar to native sarcoplasmic vesicles. 2) In the presence of Mg2+ and ATP the activity maxim um (up to 180% of control) was broadened and shifted towards a higher degree of thiol blockage. Concomitantly the modification and inactivation rates were considerably reduced. 3) Glycerol (10 -30 % , v/v) slightly enhanced the ATPase activity maximum and reduced the rate of inactivation essentially only by decreasing the DTNB modification rate. 4) In the presence of sufficient myristoylglycerophosphocholine for solubilization no activation was observed. 5) The steady state level of phosphoprotein from ATP was raised to about 150% of the control level 10 s after addition of DTNB (about 1/2 thiol blocked), followed by a linear decrease with the number of thiols labeled, while the Ca2+-dependent ATPase activity of preparations modified under equivalent conditions (10-4 м Ca2+ and 2 x 10-3 м Mg2+ present) showed a broader maximum corresponding to 1.5 thiols blocked.


1982 ◽  
Vol 202 (2) ◽  
pp. 289-301 ◽  
Author(s):  
Giovanni Salviati ◽  
Pompeo Volpe ◽  
Sergio Salvatori ◽  
Romeo Betto ◽  
Ernesto Damiani ◽  
...  

1. Microsomes were isolated from rabbit fast-twitch and slow-twitch muscle and were separated into heavy and light fractions by centrifugation in a linear (0.3–2m) sucrose density gradient. The membrane origin of microsomal vesicles was investigated by studying biochemical markers of the sarcoplasmic-reticulum membranes and of surface and T-tubular membranes, as well as their freeze-fracture properties. 2. Polyacrylamide-gel electrophoresis showed differences in the Ca2+-dependent ATPase/calsequestrin ratio between heavy and light fractions, which were apparently consistent with their respective origin from cisternal and longitudinal sarcoplasmic reticulum, as well as unrelated differences, such as peptides specific to slow-muscle microsomes (mol.wts. 76000, 60000, 56000 and 45000). 3. Freeze-fracture electron microscopy of muscle microsomes demonstrated that vesicles truly derived from the sarcoplasmic reticulum, with an average density of 9nm particles on the concave face of about 3000/μm2 for both fast and slow muscle, were admixed with vesicles with particle densities below 1000/μm2. 4. As determined in the light fractions, the sarcoplasmic-reticulum vesicles accounted for 84% and 57% of the total number of microsomal vesicles, for fast and slow muscle respectively. These values agreed closely with the percentage values of Ca2+-dependent ATPase protein obtained by gel densitometry. 5. The T-tubular origin of vesicles with a smooth concave fracture face in slow-muscle microsomes is supported by their relative high content in total phospholipid and cholesterol, compared with the microsomes of fast muscle, and by other correlative data, such as the presence of (Na++K+)-dependent ATPase activity and of low amounts of Na+-dependent membrane phosphorylation. 6. Among intrinsic sarcoplasmic-reticulum membrane proteins, a proteolipid of mol.wt. 12000 is shown to be identical in the microsomes of both fast and slow muscle and the Ca2+-dependent ATPase to be antigenically and catalytically different, though electrophoretically homogeneous. 7. Basal Mg2+-activated ATPase activity was found to be high in light microsomes from slow muscle, but its identification with an enzyme different from the Ca2+-dependent ATPase is still not conclusive. 8. Enzyme proteins that are suggested to be specific to slow-muscle longitudinal sarcoplasmic reticulum are the flavoprotėin NADH:cytochrome b5 reductase (mol.wt. 32000), cytochrome b5 (mol.wt. 17000) and the stearoyl-CoA desaturase, though essentially by criteria of plausibility.


1993 ◽  
Vol 264 (5) ◽  
pp. C1308-C1315 ◽  
Author(s):  
L. M. Schulte ◽  
J. Navarro ◽  
S. C. Kandarian

Hindlimb unweighting (HU) causes upregulation of several muscle-specific genes responsible for the slow-to-fast transition in soleus skeletal muscle properties despite the profound muscle atrophy. The purpose of this study was to examine the expression of the fast and slow isoforms of the sarcoplasmic reticulum Ca(2+)-ATPase at the mRNA and protein level in the soleus muscle over a time course of HU and relate them to Ca(2+)-dependent ATPase activity and selected contractile properties. mRNA levels of the acetylcholine receptor (AChR) were measured to compare the signal of unweighting with denervation. Atrophy of the soleus muscles from tail-suspended rats was observed at all time points with muscle mass decreased by 52% at 28 days of HU (P < 0.05). Northern blot analysis showed the relative expression of the fast Ca2+ pump mRNA increased by 0, 250, 910, 1,340, and 4,050% over control levels at 1, 4, 7, 14, and 28 days of HU, respectively, whereas changes in slow mRNA were variable and modest in comparison. For the same time points, Western blot analysis showed relative expression of the fast Ca2+ pump protein increased by 30, 110, 320, 280, and 300% over control levels, whereas the slow-pump protein expression was unchanged except for a 75% decrease at 28 days of HU. Specific Ca(2+)-dependent ATPase activity was increased (P < 0.05) by 170% at 28 days of HU. Contractile properties measured in vitro at 14 and 28 days revealed time to peak tension and one-half relaxation time were shortened (P < 0.05) and a rightward shift in the tension-frequency curves in unloaded soleus muscles.(ABSTRACT TRUNCATED AT 250 WORDS)


1981 ◽  
Vol 59 (12) ◽  
pp. 1214-1218 ◽  
Author(s):  
A. N. Belcastro ◽  
M. Rossiter ◽  
M. P. Low ◽  
M. M. Sopper

The purpose of this study was to examine the effects of varying Ca2+ concentration on the Ca2+ activated sarcoplasmic reticulum (SR) ATPase activity of fast-twitch (FT) skeletal muscle at exhaustion and during recovery. Wistar rats (200 g) were assigned to control (C), exhausted (E), and three recovery groups (R) at 5, 15, and 30 min. Following exhaustion on a motor-driven treadmill, the gastrocnemius muscles from all groups were excised and frozen. Muscle samples were assayed for ATPase activity in a Ca2+ – ethyleneglycol bis (β-aminoethyl ether)-N,N′-tetraacetic acid (EGTA) buffering system. At 1.25 μM Ca2+, a significant depression in Ca2+ activated ATPase activity occurred in the E, 5R, 15R, and 30R groups (1.61 ± 0.17, 1.87 ± 0.14, 1.43 ± 0.29, and 1.62 ± 0.1 μmol Pi∙mg−1∙10 min−1) compared with C values (2.41 ± 0.34 μmol Pi∙mg−1∙10 min−1) (p ≤ 0.05). At 5.0 μM, Ca2+ activated ATPase activity remained depressed in the E, 5R, and 15R groups compared with C and 30R groups (p ≤ 0.05). At 0.75 μM Ca2+, there was no significant difference between groups (p ≥ 0.05). The results suggest that Ca2+ activated SR ATPase activity of fatigued FT muscle may contribute to the decreased force production at exhaustion.


1982 ◽  
Vol 243 (3) ◽  
pp. C156-C160 ◽  
Author(s):  
D. H. Kim ◽  
F. A. Witzmann ◽  
R. H. Fitts

The effect of 6 wk of hindlimb immobilization on rat skeletal muscle sarcoplasmic reticulum (SR) was determined in the slow-twitch, type I soleus (SOL), the fast-twitch, type IIA deep region of the vastus lateralis (DVL), and the fast-twitch, type IIB superficial region of the vastus lateralis (SVL). Immobilization produced a significant decline in the Ca2+ uptake rate (Vmax) of SR vesicles from the slow SOL (0.930 +/- 0.116 to 0.365 +/- 0.071 mumol Ca2+ . mg-1 . min-1), while the SR Vmax increased in the fast SVL (2.763 +/- 0.133 to 5.209 +/- 0.687) and was unaltered in the DVL. Vesicles from the fast SVL and DVL also exhibited a higher total Ca2+ uptake capacity following immobilization. An evaluation of the time course of the immobilization-mediated effect revealed an increased Ca2+ uptake capacity in all three samples after 1 wk. In the SOL total Ca2+ uptake returned to control level after 2 wk, while in the fast-twitch muscles the higher capacities were maintained. The Ca2+-stimulated SR ATPase activity was not altered in any of the muscles studies, although the total SR ATPase activity increased twofold in the slow SOL.


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