Time course adaptations in rat skeletal muscle isomyosins during compensatory growth and regression

1987 ◽  
Vol 63 (5) ◽  
pp. 2111-2121 ◽  
Author(s):  
R. W. Tsika ◽  
R. E. Herrick ◽  
K. M. Baldwin
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Time Course ◽  
Compensatory Growth ◽  
Myosin Isoforms ◽  
Plantaris Muscle ◽  
Slow Myosin ◽  
Protein Pool ◽  
Isoform Expression ◽  
Myofibril Protein

The purpose of this study was to ascertain the time course of change during both compensatory growth (hypertrophy) and subsequent growth regression on myosin isoform expression in rodent fast-twitch plantaris muscle in response to functional overload (induced by removal of synergists). Peak hypertrophy of the plantaris muscle (92%) occurred after 9 wk of overload. After 7 wk of overload regression (induced by a model of hindlimb unweighting), muscle weight returned to within 30% of control values. Myofibril protein content (mg/g muscle) remained relatively constant throughout the overload period but became significantly depressed relative to control values after 7 wk of regression. However, when expressed on a per muscle basis (mg/muscle) no differences existed at this time point (t = 7 wk regression). The distribution of native myosin isoforms in the myofibril protein pool of the overloaded plantaris muscle reflected a progressive increase (23% at t = 9 wk; P less than 0.001) in the relative proportion of slow myosin (Sm). This change was also accompanied by increases in intermediate myosin (Im) as well as the repression of the fast myosin one (Fm1) isoform (P less than 0.001). These shifts in Sm and Fm1 isoform expression were gradually reversed during the regression period, whereas Im remained elevated relative to control values. These adaptive changes in myosin isoform expression during both hypertrophy and regression were further supported by concomitant shifts in both myosin adenosinetriphosphatase (ATPase) activity (decreased during overload) and slow myosin light chain (SLC) expression. However, during regression the changes in myosin isoform expression and myosin ATPase were not as synchronous as they were during overload. Estimation of the mixed myosin heavy chain (MHC) half-life (t 1/2), using a linear model that assumes zero-order synthesis and first-order degradation kinetics, revealed t 1/2 values of approximately 19 and 10 days for the overload and regression periods, respectively. Collectively these data suggest that 1) skeletal muscle myosin isoforms and corresponding ATPase activity are in a dynamic state of change, although not completely synchronous, in response to altered muscle stress, and 2) the kinetics of change in the mixed MHC protein pool are slower during compensatory growth compared with regression of growth.

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.

Time course of soleus muscle myosin expression during hindlimb suspension and recovery

1987 ◽  
Vol 63 (1) ◽  
pp. 130-137 ◽  
Author(s):  
D. B. Thomason ◽  
R. E. Herrick ◽  
D. Surdyka ◽  
K. M. Baldwin
Keyword(s):  
Protein Expression ◽  
Soleus Muscle ◽  
Time Course ◽  
Weight Bearing ◽  
Relative Proportion ◽  
Contractile Protein ◽  
Myosin Isoforms ◽  
Hindlimb Unweighting ◽  
Loss Of Weight ◽  
Myofibril Protein

This study examined the time course of adult rodent soleus muscle myofibril and myosin isoform protein expression after 4, 8, 16, 28, and 56 days of hindlimb unweighting by tail suspension (S). The time course of soleus muscle recovery (R) was also examined after 28 days of hindlimb unweighting with an additional 4, 8, 16, and 28 days of unrestricted cage activity. During suspension, soleus muscle myofibril protein rapidly decreased from 34.3 +/- 3.1 (1.96SE) mg/pair in the control (C) group to 6.9 +/- 1.4 (1.96SE) mg/pair in S (t = 56 days). The calculated first-order degradation rate constant for this loss was kd = 0.17 days-1 [half time (t1/2) = 4.1 days]. The estimated slow myosin (SM) isoform content decreased from 13.4 +/- 2.0 (1.96SE) mg/pair in C to 2.1 +/- 0.2 (1.96SE) mg/pair in S (kd = 0.19 days-1, t1/2 = 3.6 days). The relative proportion of other myosin isoforms was increased at 28 and 56 days of suspension, reflecting an apparent de novo synthesis and the loss of SM. Recovery of contractile protein after 28 days of suspension was slower for both the myofibril protein and the SM isoform (kd = 0.07 days-1, t1/2 = 10 days). These data suggest that loss of weight bearing specifically affected the mechanisms of contractile protein expression reflected in soleus muscle protein degradation processes. In addition, the expression of the myosin isoforms were apparently differentially affected by the loss of weight-bearing activity.

scholarly journals Myosin isozymes in normal and cross-reinnervated cat skeletal muscle fibers.

1983 ◽  
Vol 97 (3) ◽  
pp. 756-771 ◽  
Author(s):  
G F Gauthier ◽  
R E Burke ◽  
S Lowey ◽  
A W Hobbs
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Muscle Fibers ◽  
Motor Units ◽  
Myosin Atpase ◽  
Light Chains ◽  
Slow Myosin ◽  
Fast Myosin ◽  
Physiological Properties ◽  
Contraction Times

Immunocytochemical characteristics of myosin have been demonstrated directly in normal and cross-reinnervated skeletal muscle fibers whose physiological properties have been defined. Fibers belonging to individual motor units were identified by the glycogen-depletion method, which permits correlation of cytochemical and physiological data on the same fibers. The normal flexor digitorum longus (FDL) of the cat is composed primarily of fast-twitch motor units having muscle fibers with high myosin ATPase activity. These fibers reacted with antibodies specific for the two light chains characteristic of fast myosin, but not with antibodies against slow myosin. Two categories of fast fibers, corresponding to two physiological motor unit types (FF and FR), differed in their immunochemical response, from which it can be concluded that their myosins are distinctive. The soleus (SOL) consists almost entirely of slow-twitch motor units having muscle fibers with low myosin ATPase activity. These fibers reacted with antibodies against slow myosin, but not with antibodies specific for fast myosin. When the FDL muscle was cross-reinnervated by the SOL nerve, twitch contraction times were slowed about twofold, and motor units resembled SOL units in a number of physiological properties. The corresponding muscle fibers had low ATPase activity, and they reacted with antibodies against slow myosin only. The myosin of individual cross-reinnervated FDL muscle units was therefore transformed, apparently completely, to a slow type. In contrast, cross-reinnervation of the SOL muscle by FDL motoneurons did not effect a complete converse transformation. Although cross-reinnervated SOL motor units had faster than normal twitch contraction times (about twofold), other physiological properties characteristic of type S motor units were unchanged. Despite the change in contraction times, cross-reinnervated SOL muscle fibers exhibited no change in ATPase activity. They also continued to react with antibodies against slow myosin, but in contrast to the normal SOL, they now showed a positive response to an antibody specific for one of the light chains of fast myosin. The myosins of both fast and slow muscles were thus converted by cross-reinnervation, but in the SOL, the newly synthesized myosin was not equivalent to that normally present in either the FDL or SOL. This suggests that, in the SOL, alteration of the nerve supply and the associated dynamic activity pattern are not sufficient to completely respecify the type of myosin expressed.

Enzymes of glutamine metabolism in inflammation associated with skeletal muscle hypertrophy

1989 ◽  
Vol 257 (6) ◽  
pp. E885-E894 ◽  
Author(s):  
T. B. Kelso ◽  
C. R. Shear ◽  
S. R. Max
Keyword(s):  
Skeletal Muscle ◽  
Connective Tissue ◽  
Glutamine Synthetase ◽  
Pentose Phosphate Pathway ◽  
Tissue Repair ◽  
Time Course ◽  
Pentose Phosphate ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Plantaris Muscle

Glutamine synthesis and utilization were studied in the plantaris muscle after removal of its functional synergists, the soleus and gastrocnemius muscles. Rat plantaris muscle was compared with unoperated controls at 7, 14, and 30 days after synergist ablation and induction of hypertrophy. Glutamine synthetase activity increased from 6.17 +/- 1.77 to 33.92 +/- 2.23 nmol.h-1.mg protein-1, and glutaminase activities increased from 98.63 +/- 23.05 to 478.70 +/- 64.17 nmol.h-1.mg protein-1 7 days after surgery and remained elevated at 14 and 30 days. Sham-operated controls examined 7 days after surgery did not exhibit significantly increased glutamine synthetase activity. Histological examination revealed a large proliferation of connective tissue cells, as well as cells involved in tissue repair and inflammation; this influx was maximal 1 wk after surgery. The activity of the oxidative enzymes of the pentose phosphate pathway increased from 3.08 +/- 4.31 to 20.86 +/- 1.13 nmol.min-1.mg protein-1 1 wk after surgery. The time course of changes in pentose phosphate pathway enzymes was similar to that of the increases in glutamine synthetase, glutaminase, and cellular infiltration. Increases in muscle wet weight followed a different time course than changes in glutamine synthetase, glutaminase, and pentose phosphate pathway activities. It is concluded that the initial increases in plantaris muscle weight are probably due to edema, connective tissue proliferation, and cells involved in tissue repair and inflammation. The increase in glutamine synthetase activity appears to occur in skeletal muscle, whereas the changes in glutaminase and pentose phosphate pathway activities appear to represent infiltrating inflammatory cells. Furthermore, the increase in glutamine synthetase activity may serve to support the infiltrating cells, which appear to lack substantial capacity for glutamine production. These results represent a functional relationship between skeletal muscle glutamine synthesis and utilization by cells mediating inflammation and connective tissue repair and synthesis.

IIx and slow myosin expression follow mitochondrial increases in transforming muscle fibers

1993 ◽  
Vol 265 (1) ◽  
pp. C79-C84 ◽  
Author(s):  
J. Jacobs-El ◽  
W. Ashley ◽  
B. Russell
Keyword(s):  
Fiber Type ◽  
Fiber Types ◽  
Myosin Isoforms ◽  
Metabolic Demand ◽  
Type Conversion ◽  
Oxidative Potential ◽  
Slow Myosin ◽  
Fiber Analysis ◽  
Mrna Content ◽  
Isoform Expression

Metabolic profile and contractile isoform expression commonly define classic fiber types in skeletal muscle. Little is known about how metabolic requirements determine expression of fast IIx and slow myosin isoforms in muscles undergoing fiber type conversion. Tibialis anterior muscles from female New Zealand White rabbits were stimulated continuously at 10 Hz for 4-21 days. Quantitative fiber analysis was made for oxidative potential by histochemistry and for fast IIx and slow myosin mRNA content by in situ hybridization. In control muscle we found 3 +/- 0.27% fibers coexpress both fast IIx and slow myosin mRNA and so were not assignable to a classic fiber type. After stimulation, increase in fiber oxidative potential was detectable by 4 days and preceded IIx mRNA increases on a fiber-by-fiber basis. Slow myosin transcripts were detected by 7 days in fibers with higher oxidative levels. Coexpression of IIx and slow transcripts peaked at 22 +/- 2.5% of fibers by 7 days. IIx then declined, leaving slow myosin expressed in 62 +/- 0.45% of fibers by 3 wk. We conclude that during fiber type transformation individual fibers can transcribe two myosin mRNAs synchronously. Metabolic demand precedes and may be linked to IIx and slow myosin isoform expression.

Effect of disuse on sarcoplasmic reticulum in fast and slow skeletal muscle

1982 ◽  
Vol 243 (3) ◽  
pp. C156-C160 ◽  
Author(s):  
D. H. Kim ◽  
F. A. Witzmann ◽  
R. H. Fitts
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Time Course ◽  
Vastus Lateralis ◽  
Control Level ◽  
Type I ◽  
Uptake Capacity ◽  
Three Samples ◽  
Fast Twitch

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.

TIME COURSE ADAPTATIONS IN RODENT SKELETAL MUSCLE MYOSIN ISOFORMS IN RESPONSE TO COMPENSATORY OVERLOAD

1986 ◽  
Vol 18 (supplement) ◽  
pp. S66
Author(s):  
R. W. TSIKA ◽  
R. E. HERRICK ◽  
K. M. BALDWIN
Keyword(s):  
Skeletal Muscle ◽  
Time Course ◽  
Myosin Isoforms ◽  
Skeletal Muscle Myosin ◽  
Muscle Myosin

Cocaine alters myosin isoform expression in the rat soleus

1995 ◽  
Vol 79 (2) ◽  
pp. 514-517 ◽  
Author(s):  
M. C. Prevost ◽  
A. G. Nelson ◽  
K. P. Kelly ◽  
D. H. Han ◽  
R. K. Conlee
Keyword(s):  
Myosin Isoforms ◽  
Saline Injection ◽  
Sprague Dawley ◽  
Slow Myosin ◽  
Cocaine Administration ◽  
Heavy Chains ◽  
Sprague Dawley Rats ◽  
Chronic Cocaine ◽  
Isoform Expression

The purpose of this study was to determine whether chronic cocaine administration alters the expression of myosin isoforms in the rat soleus. Forty-five adult Sprague-Dawley rats were divided into three groups: chronic cocaine (n = 15), 12.5 mg/kg cocaine-HCl injected intraperitoneally twice daily for 14 days and one injection of cocaine (12.5 mg/kg ip) on day 15; acute cocaine (n = 15), saline injections twice daily for 14 days and one injection of cocaine (12.5 mg/kg ip) on day 15; and chronic saline (n = 15), saline injections twice daily for 14 days and one saline injection on day 15. Myosin isoform content of the soleus (native and heavy chains) was identified by electrophoresis. The solei samples from the chronic saline and acute cocaine animals contained slow myosin only. However, solei samples from the chronic cocaine group contained slow myosin and two to three other myosin isoforms and the associated heavy chains IIa and IIx. Therefore, chronic cocaine administration causes in the rat soleus a shift in myosin expression from slow isoforms to fast isoforms.

Competitive control of myosin expression: hypertrophy vs. hyperthyroidism

1991 ◽  
Vol 70 (5) ◽  
pp. 2328-2330 ◽  
Author(s):  
C. D. Ianuzzo ◽  
N. Hamilton ◽  
B. Li
Keyword(s):  
Skeletal Muscle ◽  
Phenotypic Expression ◽  
Compensatory Hypertrophy ◽  
Surgical Removal ◽  
Type I ◽  
Myosin Isoforms ◽  
Skeletal Muscle Myosin ◽  
Slow Myosin ◽  
Fast Myosin ◽  
Muscle Myosin

The competition between two opposing influences on the phenotypic expression of skeletal muscle myosin were studied to determine which was the dominant regulator. Experimental hyperthyroidism, which induces fast myosin expression, was produced by subcutaneous implantation of a 40-day constant-time-release triiodothyronine pellet. Compensatory hypertrophy, which induces slow myosin expression, was produced by surgical removal of a synergistic hindlimb muscle. Hyperthyroidism increased the percentage of type II fibers and the fast myosin isoforms in both the plantaris and soleus muscles. Hypertrophy significantly increased the percentage of type I fibers and the slow myosin type in the plantaris and soleus muscles. However, with the simultaneous introduction of hyperthyroidism and hypertrophy, only the hyperthyroid effects were observed. Hyperthyroidism and not physiological demand was found to be the dominant regulator of skeletal muscle myosin expression.

UPTAKE OF OXYTOCIN IN TISSUES AFTER INTRAVENOUS ADMINISTRATION OF TRITIATED OXYTOCIN IN RATS

1969 ◽  
Vol 61 (3) ◽  
pp. 432-440 ◽  
Author(s):  
Ingvar Sjöholm ◽  
Gunnar Rydén
Keyword(s):  
Skeletal Muscle ◽  
Distribution Pattern ◽  
Intravenous Injection ◽  
Intravenous Administration ◽  
Time Course ◽  
Tritiated Water ◽  
Preferential Distribution ◽  
Time Period ◽  
Initial Uptake

ABSTRACT The distribution of oxytocin in the kidneys, liver, uterus and skeletal muscle of the rat was followed during 10 min after intravenous injection of tritium labelled oxytocin. Oxytocin was found to be taken up and degraded mainly in the kidneys and the liver. After 150 seconds no intact oxytocin could be detected in these organs. The time course of the distribution of the radioactivity in the liver and the skeletal muscle showed no noteworthy characteristics, whereas a different course was found in the kidneys and in the uterus. In the kidneys, the radioactivity increased continuously from 60 to 200 seconds after the injection, indicating an accumulation of oxytocin or its metabolites in the kidneys. In the uterus a high initial uptake was observed, followed by a decrease of the radioactivity from 60 to 100 seconds after the injection. This distribution pattern was specific to oxytocin, since the uptake of tritiated tyrosine and tritiated water was almost constant during the same time period. These findings may indicate a preferential distribution of oxytocin to the uterus.

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