Shortening velocity and ATPase activity of rat skeletal muscle fibers: effects of endurance exercise training

1994 ◽  
Vol 266 (6) ◽  
pp. C1699-C1713 ◽  
Author(s):  
J. M. Schluter ◽  
R. H. Fitts
Keyword(s):  
Atpase Activity ◽  
Endurance Exercise ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Treadmill Running ◽  
Type I ◽  
Marker Enzyme ◽  
Shortening Velocity

Mechanical properties were measured in single skinned fibers from rat hindlimb muscle to test the hypothesis that the fast type IIb fiber exhibits a higher maximal shortening velocity (Vo) than the fast type IIa fiber and that the difference is directly attributable to a higher myofibrillar adenosinetriphosphatase (ATPase) activity in the type IIb fiber. Additional measurements were made to test the hypotheses that regular endurance exercise increases and decreases the Vo of the type I and IIa fiber, respectively, and that the altered Vo is associated with a corresponding change in the fiber ATPase activity. Rats were exercised by 8-12 wk of treadmill running for 2 h/day, 5 day/wk, up a 15% grade at a speed of 27 m/min. Fiber Vo was determined by the slack test, and the ATPase was measured fluorometrically in the same fiber. The myosin isozyme profile of each fiber was subsequently determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The mean +/- SE Vo (7.9 +/- 0.22 fiber lengths/s) of the type IIb fiber was significantly greater than the type IIa fiber (4.4 +/- 0.21 fiber lengths/s), and the higher Vo was associated with a higher ATPase activity (927 +/- 70 vs. 760 +/- 60 microM.min-1.mm-3). The exercise program induced cardiac hypertrophy and an approximately twofold increase in the mitochondrial marker enzyme citrate synthase. Exercise had no effect on fiber diameter or peak tension per cross-sectional area in any fiber type, but, importantly, it significantly increased (23%) both the Vo and the ATPase activity of the slow type I fiber of the soleus.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Force-velocity and power characteristics of rat soleus muscle fibers after hindlimb suspension

1994 ◽  
Vol 77 (4) ◽  
pp. 1609-1616 ◽  
Author(s):  
K. S. McDonald ◽  
C. A. Blaser ◽  
R. H. Fitts
Keyword(s):  
Isometric Force ◽  
Fiber Type ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Hindlimb Suspension ◽  
Type I ◽  
Shortening Velocity ◽  
Power Characteristics ◽  
Sds Page ◽  
Force Velocity

The effects of 1, 2, and 3 wk of hindlimb suspension (HS) on force-velocity and power characteristics of single rat soleus fibers were determined. After 1, 2, or 3 wk of HS, small fiber bundles were isolated, placed in skinning solution, and stored at -20 degrees C until studied. Single fibers were isolated and placed between a motor arm and force transducer, functional properties were studied, and fiber protein content was subsequently analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Additional fibers were isolated from soleus of control and after 1 and 3 wk of HS, and fiber type distribution and myosin light chain stoichiometry were determined from SDS-PAGE analysis. After 1 wk of HS, percent type I fibers declined from 82 to 74%, whereas hybrid fibers increased from 10 to 18%. Percent fast type II fibers increased from 8% in control and 1 wk of HS to 26% by 3 wk of HS. Most fibers showed an increased unloaded maximal shortening velocity (Vo), but myosin heavy chain remained entirely slow type I. The mechanism for increased Vo is unknown. There was a progressive decrease in fiber diameter (14, 30, and 38%) and peak force (38, 56, and 63%) after 1, 2, and 3 wk of HS, respectively. One week of HS resulted in a shift of the force-velocity curve, and between 2 and 3 wk of HS the curve shifted further such that Vo was higher than control at all relative loads < 45% peak isometric force. Peak absolute power output of soleus fibers progressively decreased through 2 wk of HS but showed no further change at 3 wk.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effect of hindlimb unweighting on single soleus fiber maximal shortening velocity and ATPase activity

1993 ◽  
Vol 74 (6) ◽  
pp. 2949-2957 ◽  
Author(s):  
K. S. McDonald ◽  
R. H. Fitts
Keyword(s):  
Atpase Activity ◽  
Soleus Muscle ◽  
Time Course ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Maximal Velocity ◽  
Shortening Velocity ◽  
Hindlimb Unweighting ◽  
Fast Myosin ◽  
Highly Correlated

This study characterizes the time course of change in single soleus muscle fiber size and function elicited by hindlimb unweighting (HU) and analyzes the extent to which varying durations of HU altered maximal velocity of shortening (Vo), myofibrillar adenosinetriphosphatase (ATPase), and relative content of slow and fast myosin in individual soleus fibers. After 1, 2, or 3 wk of HU, soleus muscle bundles were prepared and stored in skinning solution at -20 degrees C. Single fibers were isolated and mounted between a motor arm and a transducer, and fiber force, Vo, and ATPase activity were measured. Fiber myosin content was determined by one-dimensional sodium dodecyl sulfate- (SDS) polyacrylamide gel electrophoresis. After 1, 2, and 3 wk of HU, soleus fibers exhibited a progressive reduction in fiber diameter (16, 22, and 42%, respectively) and peak force (42, 48, and 72%, respectively). Peak specific tension was significantly reduced after 1 wk of HU (18%) and showed no further change in 2–3 wk of HU. During 1 and 3 wk of HU, fiber Vo and ATPase showed a significant increase. By 3 wk, Vo had increased from 1.32 +/- 0.04 to 2.94 +/- 0.17 fiber lengths/s and fiber ATPase from 291 +/- 16 to 1,064 +/- 128 microM.min-1 x mm-3. The percent fibers expressing fast myosin heavy chain increased from 4% to 29% by 3 wk of HU, and Vo and ATPase activity within a fiber were highly correlated.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Soleus fiber force and maximal shortening velocity after non-weight bearing with intermittent activity

1996 ◽  
Vol 80 (3) ◽  
pp. 981-987 ◽  
Author(s):  
J. J. Widrick ◽  
J. J. Bangart ◽  
M. Karhanek ◽  
R. H. Fitts
Keyword(s):  
Isometric Force ◽  
Weight Bearing ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Cross Sectional Area ◽  
Type I ◽  
Sectional Area ◽  
Shortening Velocity ◽  
Adult Rats ◽  
Cross Sectional

This study examined the effectiveness of intermittent weight bearing (IWB) as a countermeasure to non-weight-bearing (NWB)-induced alterations in soleus type I fiber force (in mN), tension (Po; force per fiber cross-sectional area in kN/m-2), and maximal unloaded shortening velocity (Vo, in fiber lengths/s). Adult rats were assigned to one of the following groups: normal weight bearing (WB), 14 days of hindlimb NWB (NWB group), and 14 days of hindlimb NWB with IWB treatments (IWB group). The IWB treatment consisted of four 10-min periods of standing WB each day. Single, chemically permeabilized soleus fiber segments were mounted between a force transducer and position motor and were studied at maximal Ca2+ activation, after which type I fiber myosin heavy-chain composition was confirmed by sodium dodecyl sufate-polyacrylamide gel electrophoresis. NWB resulted in a loss in relative soleus mass (-45%), with type I fibers displaying reductions in diameter (-28%) and peak isometric force (-55%) and an increase in Vo (+33%). In addition, NWB induced a 16% reduction in type I fiber Po, a 41% reduction in type I fiber peak elastic modulus [Eo, defined as (delta force/delta length) x (fiber length/fiber cross-sectional area] and a significant increase in the Po/Eo ratio. In contrast to NWB, IWB reduced the loss of relative soleus mass (by 22%) and attenuated alterations in type I fiber diameter (by 36%), peak force (by 29%), and Vo (by 48%) but had no significant effect on Po, Eo, or Po/Eo. These results indicate that a modest restoration of WB activity during 14 days of NWB is sufficient to attenuate type I fiber atrophy and to partially restore type I peak isometric force and Vo to WB levels. However, the NWB-induced reductions in Po and Eo, which we hypothesize to be due to a decline in the number and stiffness of cross bridges, respectively, are considerably less responsive to this countermeasure treatment.

Inducible isoform of HSP70 is constitutively expressed in a muscle fiber type specific pattern

1991 ◽  
Vol 261 (5) ◽  
pp. C774-C779 ◽  
Author(s):  
M. Locke ◽  
E. G. Noble ◽  
B. G. Atkinson
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Constitutive Expression ◽  
Muscle Fiber Types ◽  
Type I ◽  
Fiber Types ◽  
Nylon Membrane ◽  
White Gastrocnemius

The most prominent group of stress or heat-shock proteins (HSPs) has an Mr of approximately 70,000 and is collectively referred to as the HSP70 family. The extent of stress inducibility and subcellular location of the various HSP70 isoforms differ, but all appear to be involved with ATP-dependent stabilization or solubilization of proteins. One isoform, termed the inducible isoform of HSP70 (HSP72i), is normally absent in unstressed cells. In a previous study, we detected a protein corresponding in Mr and pI to HSP72i in unstressed rat muscle. Therefore, it was of interest to determine if this expression in unstressed muscle cells is general or confined to specific muscle fiber types. To answer this question we have employed various rat hindlimb muscles that differ in fiber type proportion from predominantly type I (soleus) to predominantly type IIB (white gastrocnemius). Proteins from muscle homogenates were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, blotted to a nylon membrane, probed with a monoclonal antibody for HSP72i, and visualized using an alkaline phosphatase-conjugated secondary antibody. Immunoblot analyses demonstrate the constitutive expression of HSP72i in rat muscles comprised primarily of type I muscle fibers (soleus), but not in muscles comprised primarily of type IIB fibers (white gastrocnemius). In muscles of mixed fiber type, HSP72i content is roughly proportional to the percentage of type I fibers. These results substantiate that unstressed rat muscles express the inducible HSP72 isoform and demonstrate that its constitutive expression is proportional to the type I muscle fiber composition.

Exercise training, glucose transporters, and glucose transport in rat skeletal muscles

1992 ◽  
Vol 262 (1) ◽  
pp. C9-C14 ◽  
Author(s):  
K. J. Rodnick ◽  
E. J. Henriksen ◽  
D. E. James ◽  
J. O. Holloszy
Keyword(s):  
Glucose Transport ◽  
Endurance Exercise ◽  
Glucose Transporter ◽  
Citrate Synthase ◽  
Wheel Running ◽  
Fiber Type ◽  
Type I ◽  
Voluntary Wheel Running ◽  
Glut1 Protein ◽  
Voluntary Wheel

It was previously found that voluntary wheel running induces an increase in the insulin-sensitive glucose transporter, i.e., the GLUT4 isoform, in rat plantaris muscle (K. J. Rodnick, J. O. Holloszy, C. E. Mondon, and D. E. James. Diabetes 39: 1425-1429, 1990). The present study was undertaken to determine whether 1) the increase in muscle GLUT4 protein is associated with an increase in maximally stimulated glucose transport activity, 2) a conversion of type IIb to type IIa or type I muscle fibers plays a role in the increase in GLUT4 protein, and 3) an increase in the GLUT1 isoform is a component of the adaptation of muscle to endurance exercise. Five weeks of voluntary wheel running that resulted in a 33% increase in citrate synthase activity induced a 50% increase in GLUT4 protein in epitrochlearis muscles of female Sprague-Dawley rats. The rate of 2-deoxy-glucose transport maximally stimulated with insulin or insulin plus contractions was increased approximately 40% (P less than 0.05). There was no change in muscle fiber type composition, evaluated by myosin ATPase staining, in the epitrochlearis. There was also no change in GLUT1 protein concentration. We conclude that an increase in GLUT4, but not of GLUT1 protein, is a component of the adaptive response of muscle to endurance exercise and that the increase in GLUT4 protein is associated with an increased capacity for glucose transport.

Single muscle fiber enzyme shifts with hindlimb suspension and immobilization

1989 ◽  
Vol 256 (5) ◽  
pp. C1082-C1091 ◽  
Author(s):  
R. H. Fitts ◽  
C. J. Brimmer ◽  
A. Heywood-Cooksey ◽  
R. J. Timmerman
Keyword(s):  
Citrate Synthase ◽  
Fiber Type ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Glycolytic Enzymes ◽  
Hindlimb Suspension ◽  
Metabolic Enzyme ◽  
Fiber Types ◽  
Freeze Dried ◽  
Fast Fiber

The purpose of this investigation was to determine how models of weightlessness, hindlimb suspension (HS), and hindlimb immobilization (HI) affect the metabolic enzyme profile in the slow oxidative (SO), fast oxidative glycolytic (FOG), and fast glycolytic (FG) fibers of rat hindlimb. After 1, 2, or 4 wk of HS or HI, single fibers were isolated from freeze-dried soleus and gastrocnemius muscles; a small section of each fiber was run on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels to identify fiber type, and the remaining piece was assayed for either lactate dehydrogenase (LDH) and citrate synthase (CS) or phosphofructokinase (PFK) and beta-hydroxyacyl-CoA dehydrogenase (beta-OH-acyl-CoA). Two weeks of HS induced an almost twofold increase in the activity of CS (2.13 +/- 0.13 vs. 3.60 +/- 0.26 mol.kg dry wt-1.h-1) in the SO fiber of the soleus, and the activity stayed high at 4 wk. Although the FOG fiber had significantly higher CS activity (3.85 +/- 0.29) than either the SO or FG (1.59 +/- 0.16 mol.kg dry wt-1.h-1) fiber, neither fast fiber type was altered by HS. The glycolytic enzymes LDH and PFK were both elevated in the SO fiber after HS. The increase in LDH occurred by 1 wk (14.80 +/- 1.51 vs. 8.83 +/- 0.78), whereas the activity of PFK was not significantly changed until 4 wk (1.16 +/- 0.13 vs. 0.68 +/- 0.05 mol.kg dry wt-1.h-1). The control FG fiber had the highest LDH (44.30 +/- 2.29) and PFK (2.40 +/- 0.16) activities, followed by the FOG fiber (LDH, 34.10 +/- 2.83; PFK, 1.62 +/- 0.17 mol.kg dry wt-1.h-1); however, the activities of these glycolytic enzymes in the fast fiber types were unaltered by HS. The activity of beta-OH-acyl-CoA was not affected by HS in either the slow or fast fiber types. HI showed qualitatively similar changes to those observed with HS; however, the enzyme shifts developed with a slower time course. In conclusion, both HS and HI shifted the SO fiber enzyme pattern toward that of the control FOG fiber; however, a complete conversion from the SO to FOG fiber did not occur within the 4-wk treatment period.

Changes in Myosin Expression in Denervated Laryngeal Muscle

1997 ◽  
Vol 106 (12) ◽  
pp. 1076-1081 ◽  
Author(s):  
John M. Delgaudio ◽  
James J. Sciote
Keyword(s):  
Fiber Type ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Type I ◽  
Type Ii ◽  
Laryngeal Muscle ◽  
Fiber Type Composition ◽  
Neural Input ◽  
Type Composition ◽  
Posterior Cricoarytenoid

The effects of chronic denervation on the myosin heavy chain (MyHC) content and muscle fiber type composition of rat laryngeal muscles are described. The posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles were removed 3 weeks, 3 months, and 6 months after recurrent laryngeal nerve sectioning. Myofibrillar adenosine triphosphatase staining of cryostat sections was performed, and fiber type percentages were determined. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to separate MyHC isoforms, and densitometry was subsequently used for quantitative analysis. Unoperated animals served as controls. In the PCA muscle, denervation resulted in a progressive reduction in type I MyHC (the slow-contracting isoform) to an almost complete loss at 6 months, with a concomitant increase in type II MyHCs (fast-contracting isoforms, excluding type IIL). Type IIL MyHC (laryngeal-specific isoform) remained relatively constant up to 6 months after denervation. The myosin expression in the TA muscle, which contained only type II MyHCs, remained relatively constant with denervation. Changes in fiber type composition of the muscles described from tissue staining correlated with MyHC content. These findings in laryngeal muscle confirm the dependence of type I MyHC expression upon neural input, as has been found previously in limb skeletal muscles. Since the expression of all MyHCs except the IIL was modified after denervation in the PCA muscle, it is possible that the IIL isoform is maintained by factors that differ from those in the other skeletal myosins.

scholarly journals Autophagy facilitates type I collagen synthesis in periodontal ligament cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomomi Nakamura ◽  
Motozo Yamashita ◽  
Kuniko Ikegami ◽  
Mio Suzuki ◽  
Manabu Yanagita ◽  
...  
Keyword(s):  
Periodontal Ligament ◽  
Collagen Synthesis ◽  
Type I Collagen ◽  
Periodontal Diseases ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Physiological Role ◽  
Type I ◽  
Periodontal Tissue ◽  
Pdl Cells

AbstractAutophagy is a lysosomal protein degradation system in which the cell self-digests its intracellular protein components and organelles. Defects in autophagy contribute to the pathogenesis of age-related chronic diseases, such as myocardial infarction and rheumatoid arthritis, through defects in the extracellular matrix (ECM). However, little is known about autophagy in periodontal diseases characterised by the breakdown of periodontal tissue. Tooth-supportive periodontal ligament (PDL) tissue contains PDL cells that produce various ECM proteins such as collagen to maintain homeostasis in periodontal tissue. In this study, we aimed to clarify the physiological role of autophagy in periodontal tissue. We found that autophagy regulated type I collagen synthesis by elimination of misfolded proteins in human PDL (HPDL) cells. Inhibition of autophagy by E-64d and pepstatin A (PSA) or siATG5 treatment suppressed collagen production in HPDL cells at mRNA and protein levels. Immunoelectron microscopy revealed collagen fragments in autolysosomes. Accumulation of misfolded collagen in HPDL cells was confirmed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. E-64d and PSA treatment suppressed and rapamycin treatment accelerated the hard tissue-forming ability of HPDL cells. Our findings suggest that autophagy is a crucial regulatory process that facilitates type I collagen synthesis and partly regulates osteoblastic differentiation of PDL cells.

Radioimmunoassay for the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen: a new serum marker of bone collagen degradation

1993 ◽  
Vol 39 (4) ◽  
pp. 635-640 ◽  
Author(s):  
J Risteli ◽  
I Elomaa ◽  
S Niemi ◽  
A Novamo ◽  
L Risteli
Keyword(s):  
Type I Collagen ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Bone Collagen ◽  
Collagen Molecule ◽  
Type I ◽  
Serum Samples ◽  
Amino Terminal ◽  
Wide Range ◽  
Carboxy Terminal

Abstract We developed a radioimmunoassay (RIA) for the carboxy-terminal telopeptides of type I collagen (ICTP), cross-linked with the helical domain of another type I collagen molecule, after isolation from human femoral bone. The cross-linked peptide was liberated by digesting insoluble, denatured bone collagen either with bacterial collagenase or with trypsin, and purified by two successive reversed-phase separations on HPLC, with monitoring of pyridinoline-specific fluorescence. The purity of the peptide was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its origin in the type I collagen fibers was determined by amino-terminal amino acid sequencing. Polyclonal antibodies and a separation reagent containing second antibody and polyethylene glycol are used in the RIA. An immunologically identical, somewhat larger antigen is present in human serum; its concentration increases in multiple myeloma and in rheumatoid arthritis. The ICTP antigen seems to be cleared from the circulation by the kidneys, because glomerular filtration rates that are two-thirds of normal or less are associated with increased circulating ICTP concentrations. The CVs of the method are between 3% and 8% for a wide range of concentrations. The analysis of 40 serum samples can be completed in 4 h.

scholarly journals Comparison of the Structural Characteristics of Native Collagen Fibrils Derived from Bovine Tendons Using Two Different Methods: Modified Acid-Solubilized and Pepsin-Aided Extraction

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 358 ◽  
Author(s):  
Haiyan Ju ◽  
Xiuying Liu ◽  
Gang Zhang ◽  
Dezheng Liu ◽  
Yongsheng Yang
Keyword(s):  
Type I Collagen ◽  
Structural Characteristics ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Dry Weight ◽  
Collagen Fibrils ◽  
Type I ◽  
X Ray Diffraction ◽  
Aggregation Structure ◽  
Native Collagen

Native collagen fibrils (CF) were successfully extracted from bovine tendons using two different methods: modified acid-solubilized extraction for A-CF and pepsin-aided method for P-CF. The yields of A-CF and P-CF were up to 64.91% (±1.07% SD) and 56.78% (±1.22% SD) (dry weight basis), respectively. The analyses of both amino acid composition and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) confirmed that A-CF and P-CF were type I collagen fibrils. Both A-CF and P-CF retained the intact crystallinity and integrity of type I collagen’s natural structure by FTIR spectra, circular dichroism spectroscopy (CD) and X-ray diffraction detection. The aggregation structures of A-CF and P-CF were displayed by UV–Vis. However, A-CF showed more intact aggregation structure than P-CF. Microstructure and D-periodicities of A-CF and P-CF were observed (SEM and TEM). The diameters of A-CF and P-CF are about 386 and 282 nm, respectively. Although both A-CF and P-CF were theoretically concordant with the Schmitt hypothesis, A-CF was of evener thickness and higher integrity in terms of aggregation structure than P-CF. Modified acid-solubilized method provides a potential non-enzyme alternative to extract native collagen fibrils with uniform thickness and integral aggregation structure.

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