scholarly journals Recovery of microvascular Po2 during the exercise off-transient in muscles of different fiber type

2004 ◽  
Vol 96 (3) ◽  
pp. 1039-1044 ◽  
Author(s):  
Paul McDonough ◽  
Brad J. Behnke ◽  
Timothy I. Musch ◽  
David C. Poole
Keyword(s):  
Fiber Type ◽  
Oxidative Capacity ◽  
Type I ◽  
Sprague Dawley ◽  
Vascular Control ◽  
Mean Response Time ◽  
Slow Twitch Muscle ◽  
Slow Twitch ◽  
Muscle Energetic ◽  
Slow Twitch Fibers

The speed with which muscle energetic status recovers after exercise is dependent on oxidative capacity and vascular O2 pressures. Because vascular control differs between muscles composed of fast- vs. slow-twitch fibers, we explored the possibility that microvascular O2 pressure (PmvO2; proportional to the O2 delivery-to-O2 uptake ratio) would differ during recovery in fast-twitch peroneal (Per: 86% type II) compared with slow-twitch soleus (Sol: 84% type I). Specifically, we hypothesized that, in Per, PmvO2 would be reduced immediately after contractions and would recover more slowly during the off-transient from contractions compared with Sol. The Per and Sol muscles of six female Sprague-Dawley rats (weight = ∼220 g) were studied after the cessation of electrical stimulation (120 s; 1 Hz) to compare the recovery profiles of PmvO2. As hypothesized, PmvO2 was lower throughout recovery in Per compared with Sol (end contraction: 13.4 ± 2.2 vs. 20.2 ± 0.9 Torr; end recovery: 24.0 ± 2.4 vs. 27.4 ± 1.2 Torr, Per vs. Sol; P ≤ 0.05). In addition, the mean response time for recovery was significantly faster for Sol compared with Per (45.1 ± 5.3 vs. 66.3 ± 8.1 s, Sol vs. Per; P < 0.05). Despite these findings, PmvO2 rose progressively in both muscles and at no time fell below end-exercise values. These data indicate that, during the recovery from contractions (which is prolonged in Per), capillary O2 driving pressure (i.e., PmvO2) is reduced in fast-compared with slow-twitch muscle. In conclusion, the results of the present investigation may partially explain the slowed recovery kinetics (phosphocreatine and O2 uptake) found previously in 1) fast- vs. slow-twitch muscle and 2) various patient populations, such as those with congestive heart failure and diabetes mellitus.

scholarly journals lncRNA-Six1 Is a Target of miR-1611 that Functions as a ceRNA to Regulate Six1 Protein Expression and Fiber Type Switching in Chicken Myogenesis

Cells ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 243 ◽  
Author(s):  
Manting Ma ◽  
Bolin Cai ◽  
Liang Jiang ◽  
Bahareldin Ali Abdalla ◽  
Zhenhui Li ◽  
...  
Keyword(s):  
Fiber Type ◽  
Muscle Fibers ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Proliferation And Differentiation ◽  
Slow Twitch Muscle ◽  
Fast Twitch Muscle ◽  
Slow Twitch ◽  
Slow Twitch Fibers ◽  
Fast Twitch

Emerging studies indicate important roles for non-coding RNAs (ncRNAs) as essential regulators in myogenesis, but relatively less is known about their function. In our previous study, we found that lncRNA-Six1 can regulate Six1 in cis to participate in myogenesis. Here, we studied a microRNA (miRNA) that is specifically expressed in chickens (miR-1611). Interestingly, miR-1611 was found to contain potential binding sites for both lncRNA-Six1 and Six1, and it can interact with lncRNA-Six1 to regulate Six1 expression. Overexpression of miR-1611 represses the proliferation and differentiation of myoblasts. Moreover, miR-1611 is highly expressed in slow-twitch fibers, and it drives the transformation of fast-twitch muscle fibers to slow-twitch muscle fibers. Together, these data demonstrate that miR-1611 can mediate the regulation of Six1 by lncRNA-Six1, thereby affecting proliferation and differentiation of myoblasts and transformation of muscle fiber types.

Contractile function of single muscle fibers after hindlimb suspension

1989 ◽  
Vol 66 (6) ◽  
pp. 2739-2749 ◽  
Author(s):  
P. R. Gardetto ◽  
J. M. Schluter ◽  
R. H. Fitts
Keyword(s):  
Contractile Function ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Hindlimb Suspension ◽  
Type I ◽  
Single Muscle ◽  
Peak Tension ◽  
Slow Twitch ◽  
Slow Twitch Fibers ◽  
Fast Twitch

The purpose of this investigation was to determine how muscle atrophy produced by the hindlimb suspension (HS) model alters the contractile function of slow- and fast-twitch single muscle fibers. After 2 wk of HS, small bundles of fibers were isolated from the soleus and the deep and superficial regions of the lateral and medial heads of the gastrocnemius, respectively. The bundles were placed in skinning solution and stored at -20 degrees C until studied. Single fibers were isolated and suspended between a motor arm and force transducer, the functional properties were studied, and subsequently the fiber type was established by myosin heavy chain (MHC) analysis on 1-D sodium dodecyl sulfate polyacrylamide gel electrophoresis. After HS, slow-twitch fibers of the soleus showed a significant reduction in fiber diameter (68 +/- 2 vs. 41 +/- 1 micron) and peak tension (1.37 +/- 0.01 vs. 0.99 +/- 0.06 kg/cm2), whereas the maximal shortening speed (Vmax) increased [1.49 +/- 0.11 vs. 1.92 +/- 0.14 fiber lengths (FL)/s]. A histogram showed two populations of fibers: one with Vmax values identical to control slow-twitch fibers and a second with significantly elevated Vmax values. This latter group frequently contained both slow and fast MHC protein isoforms. The pCa-force relation of the soleus slow-twitch fibers was shifted to the right; consequently, the free Ca2+ required for the onset of tension and for 50% of peak tension was significantly higher after HS. Slow-twitch fibers isolated from the gastrocnemius after HS showed a significant reduction in diameter (67 +/- 4 vs. 44 +/- 3 microns) and peak tension (1.2 +/- 0.06 vs. 0.96 +/- 0.07 kg/cm2), but Vmax was unaltered (1.70 +/- 0.13 vs. 1.65 +/- 0.18 FL/s). Fast-twitch fibers from the red gastrocnemius showed a significant reduction in diameter (59 +/- 2 vs. 49 +/- 3 microns) but no change in peak tension or Vmax. Fast-twitch fibers from the white superficial region of the medial head of the gastrocnemius were unaffected by HS. Collectively, these data suggest that the effects of HS on fiber function depend on the fiber type and location. Both slow-twitch type I and fast-twitch type IIa fibers atrophied; however, only slow-twitch fibers showed a decline in peak tension, and the increase in Vmax was restricted to a subpopulation of slow-twitch soleus fibers.

Kinetics of muscle deoxygenation and microvascular Po2 during contractions in rat: comparison of optical spectroscopy and phosphorescence-quenching techniques

2012 ◽  
Vol 112 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Shunsaku Koga ◽  
Yutaka Kano ◽  
Thomas J. Barstow ◽  
Leonardo F. Ferreira ◽  
Etsuko Ohmae ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Visible Light ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Fiber Type ◽  
Type I ◽  
Phosphorescence Quenching ◽  
Mean Response Time ◽  
Muscle Deoxygenation ◽  
Visible Light Spectroscopy

The overarching presumption with near-infrared spectroscopy measurement of muscle deoxygenation is that the signal reflects predominantly the intramuscular microcirculatory compartment rather than intramyocyte myoglobin (Mb). To test this hypothesis, we compared the kinetics profile of muscle deoxygenation using visible light spectroscopy (suitable for the superficial fiber layers) with that for microvascular O2 partial pressure (i.e., PmvO2, phosphorescence quenching) within the same muscle region (0.5∼1 mm depth) during transitions from rest to electrically stimulated contractions in the gastrocnemius of male Wistar rats ( n = 14). Both responses could be modeled by a time delay (TD), followed by a close-to-exponential change to the new steady level. However, the TD for the muscle deoxygenation profile was significantly longer compared with that for the phosphorescence-quenching PmvO2 [8.6 ± 1.4 and 2.7 ± 0.6 s (means ± SE) for the deoxygenation and PmvO2, respectively; P < 0.05]. The time constants (τ) of the responses were not different (8.8 ± 4.7 and 11.2 ± 1.8 s for the deoxygenation and PmvO2, respectively). These disparate (TD) responses suggest that the deoxygenation characteristics of Mb extend the TD, thereby increasing the duration (number of contractions) before the onset of muscle deoxygenation. However, this effect was insufficient to increase the mean response time. Somewhat differently, the muscle deoxygenation response measured using near-infrared spectroscopy in the deeper regions (∼5 mm depth) (∼50% type I Mb-rich, highly oxidative fibers) was slower (τ = 42.3 ± 6.6 s; P < 0.05) than the corresponding value for superficial muscle measured using visible light spectroscopy or PmvO2 and can be explained on the basis of known fiber-type differences in PmvO2 kinetics. These data suggest that, within the superficial and also deeper muscle regions, the τ of the deoxygenation signal may represent a useful index of local O2 extraction kinetics during exercise transients.

In vitro O2 uptake and histochemical fiber type of resting hamster muscles

1984 ◽  
Vol 57 (1) ◽  
pp. 246-253 ◽  
Author(s):  
S. M. Sullivan ◽  
R. N. Pittman
Keyword(s):  
Surface Area ◽  
Fiber Type ◽  
Oxidative Capacity ◽  
Histochemical Staining ◽  
Striated Muscles ◽  
Type Composition ◽  
Slow Twitch ◽  
Pattern Number ◽  
Fast Twitch

In vitro oxygen consumption (VO2), histochemical fiber type, capillary arrangement, and muscle fiber geometry were measured in three hamster striated muscles. These muscles varied markedly in their histochemical fiber type composition (% by number): retractor (70% FG, fast-twitch, glycolytic; 16% FOG, fast-twitch, oxidative-glycolytic; 14% SO, slow-twitch, oxidative); soleus (57% FOG, 43% SO), and sartorius (98% FG, 2% FOG). Sartorius VO2 [0.80 +/- 0.034 (SE) ml O2 X min-1 X 100 g-1] was significantly different (P less than 0.01) from VO2 of retractor (0.89 +/- 0.038) and soleus (1.00 +/- 0.048).The number of capillaries around a fiber and the surface area/volume were greater for FOG and SO fibers than for FG fibers. Fibers of all types appeared to be roughly elliptical in shape. Capillaries were uniformly distributed around fibers in the soleus, but they were located more toward the ends of the major diameter in the retractor and sartorius. The results suggest a relationship among a fiber's oxidative capacity (based on its histochemical staining pattern), number of surrounding capillaries and surface area/volume. Furthermore, results suggest that VO2 and capillary spacing around a fiber may depend on fiber type.

Exercise-induced cellular alterations in the diaphragm

1992 ◽  
Vol 263 (5) ◽  
pp. R1093-R1098 ◽  
Author(s):  
S. K. Powers ◽  
D. Criswell ◽  
F. K. Lieu ◽  
S. Dodd ◽  
H. Silverman
Keyword(s):  
Exercise Training ◽  
Endurance Training ◽  
Fiber Type ◽  
Capillary Density ◽  
Oxidative Capacity ◽  
Control Group ◽  
Type I ◽  
Fiber Types ◽  
Image Analysis System ◽  
Cross Sectional

Limited data exist concerning the effects of exercise training on cellular oxidative capacity in the diaphragm of senescent animals. In this study we examined the changes in cellular oxidative capacity, muscle cell cross-sectional area (CSA), and capillarity within the costal diaphragm of senescent animals after a 10-wk endurance-training program. Twelve 24-mo-old female Fischer 344 rats were divided into either a sedentary control group (n = 6) or exercise training group (n = 6). The trained animals exercised on a motor-driven treadmill (60 min/day, 5 days/wk) at a work rate equal to approximately 55-65% VO2max. Capillaries were identified histologically and fiber types determined using adenosinetriphosphatase (ATPase) histochemistry. Succinate dehydrogenase (SDH) activity and CSA in individual fibers were measured using a computerized image analysis system. Exercise training did not increase (P > 0.05) the capillary-to-fiber ratio for any fiber type. However, training significantly decreased CSA (P < 0.05) and increased capillary density (capillary number/CSA) (P < 0.05) in type I, type IIa, and type IIb fibers. Furthermore, exercise training resulted in small but significant increase in SDH activity (P < 0.05) in type I and IIa fibers, whereas training did not alter SDH activity (P > 0.05) in type IIb fibers. These data demonstrate that endurance training in senescent animals results in small relative improvements in both oxidative capacity and capillary density in costal diaphragmatic type I and IIa muscle fibers. The increase in both capillary density and fiber SDH activity was largely due to a reduction in fiber CSA.

scholarly journals Abundance of ClC-1 chloride channel in human skeletal muscle: fiber type specific differences and effect of training

2018 ◽  
Vol 125 (2) ◽  
pp. 470-478 ◽  
Author(s):  
Martin Thomassen ◽  
Morten Hostrup ◽  
Robyn M. Murphy ◽  
Brett A. Cromer ◽  
Casper Skovgaard ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Exercise Performance ◽  
Chloride Channel ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Human Muscle ◽  
Type I ◽  
Maximal Heart Rate ◽  
Channel Protein ◽  
Slow Twitch

Cl− channel protein 1 (ClC-1) may be important for excitability and contractility in skeletal muscle, but ClC-1 abundance has not been examined in human muscle. The aim of the present study was to examine ClC-1 abundance in human skeletal muscle, including fiber type specific differences and the effect of exercise training. A commercially available antibody was tested with positive and negative control tissue, and it recognized specifically ClC-1 in the range from 100 to 150 kDa. Abundance of ClC-1 was 38% higher ( P < 0.01) in fast twitch Type IIa muscle fibers than in slow twitch Type I. Muscle ClC-1 abundance did not change with 4 wk of training consisting of 30 min cycling at 85% of maximal heart rate (HRmax) and 3 × 30-s all out sprints or during a 7-wk training period with 10–12 × 30 s uphill cycling and 4–5 × ~4 min cycling at 90%–95% of HRmax. ClC-1 abundance correlated negatively ( P < 0.01) with maximal oxygen consumption ( r = –0.552) and incremental exercise performance ( r = –0.546). In addition, trained cyclists had lower ( P < 0.01) ClC-1 abundance than lesser trained individuals. The present observations indicate that a low abundance of muscle ClC-1 may be beneficial for exercise performance, but the role of abundance and regulation of ClC-1 in skeletal muscle of humans with respect to exercise performance and trainability need to be elucidated. NEW & NOTEWORTHY Abundance of the Cl− channel protein 1 (ClC-1) chloride channel may be important for excitability and contractility in human skeletal muscle and may therefore have implications for fatigue development. In this study, we confirmed ClC-1 specificity for a commercially available antibody, and this study is first to our knowledge to determine ClC-1 protein abundance in human muscle by Western blotting. We observed that abundance of ClC-1 was higher in fast compared with slow twitch fibers and lower in trained individuals than in recreationally active.

Shifts in type I fiber proportion in rat hindlimb muscle are accompanied by changes in HSP72 content

1994 ◽  
Vol 266 (5) ◽  
pp. C1240-C1246 ◽  
Author(s):  
M. Locke ◽  
B. G. Atkinson ◽  
R. M. Tanguay ◽  
E. G. Noble
Keyword(s):  
Citrate Synthase ◽  
Oxidative Capacity ◽  
Surgical Removal ◽  
Type I ◽  
Sprague Dawley ◽  
Hsp70 Family ◽  
Hindlimb Muscles ◽  
Sprague Dawley Rats ◽  
Hindlimb Muscle ◽  
Type I Fibers

Heat-shock protein 72 (HSP72), the inducible isoform of the HSP70 family, is constitutively expressed in rat hindlimb muscles in proportion to the content of type I muscle fibers. To determine whether this relationship was maintained after fiber transformation, male Sprague-Dawley rats were treated with 3,5,3'-triiodo-DL-thyronine (T3) for 40 days or underwent surgical removal of the left gastrocnemius muscle, after which the left plantaris muscle was allowed to hypertrophy for 30 days. Hypertrophied plantaris muscles exhibited an increased number of type I fibers, type I myosin heavy-chain (MHC) protein, and HSP72 content compared with contralateral muscles. Soleus muscles from rats administered T3 exhibited an increased number of type II fibers, citrate synthase activity, and decreased HSP72 content compared with soleus muscles from controls. These results indicate that the relationship between HSP72 content and type I muscle fiber-MHC composition is maintained when muscles undergo fiber transformation and substantiate that HSP72 content in rat skeletal muscle is not directly linked to a muscle's oxidative capacity.

Muscle respiratory capacity and fiber type as determinants of the lactate threshold

1980 ◽  
Vol 48 (3) ◽  
pp. 523-527 ◽  
Author(s):  
J. L. Ivy ◽  
R. T. Withers ◽  
P. J. Van Handel ◽  
D. H. Elger ◽  
D. L. Costill
Keyword(s):  
Blood Lactate ◽  
Lactate Threshold ◽  
Fiber Type ◽  
Work Rate ◽  
Respiratory Capacity ◽  
Lactate Accumulation ◽  
Blood Lactate Accumulation ◽  
Slow Twitch ◽  
The Absolute ◽  
Slow Twitch Fibers

This study examined the relationship between the respiratory capacity of an individual's skeletal muscle and the work rate at which blood lactate accumulation begins (lactate threshold). Comparisons were also made among fiber type, VO2max, and the lactate threshold. Muscle biopsies were taken from the vastus lateralis muscle for determination of respiratory capacity and fiber type (myosin ATPase). The lactate threshold was assessed in terms of both the absolute work rate (VO2) and relative work rate (%VO2max). The capacity of muscle homogenates to oxidize pyruvate was significantly (P less than 0.01) related to the absolute (r = 0.94) and relative (r = 0.83) lactate thresholds. Significant positive correlations (P less than 0.01) were also found between the percent of slow-twitch fibers and absolute (r = 0.74) and relative (r = 0.70) lactate thresholds. The results suggest that the muscle's respiratory capacity is of primary importance in determining the work rate at which blood lactate accumulation begins. They also suggest that the proportion of slow-twitch fibers may play an important role in determining the relative lactate threshold.

scholarly journals Nitric oxide synthase inhibition during treadmill exercise reveals fiber-type specific vascular control in the rat hindlimb

2010 ◽  
Vol 298 (2) ◽  
pp. R478-R485 ◽  
Author(s):  
Steven W. Copp ◽  
Daniel M. Hirai ◽  
K. Sue Hageman ◽  
David C. Poole ◽  
Timothy I. Musch
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Treadmill Exercise ◽  
Fiber Type ◽  
Muscle Blood Flow ◽  
Exercise Bout ◽  
Type I ◽  
Vascular Control ◽  
Hindlimb Muscle ◽  
The Individual

The control of vascular tone during exercise is highly complex and integrated. Specifically, in regards to the contribution of nitric oxide (NO), the observed magnitude and muscle fiber-type dependency of the NO contribution to exercise hyperemia may differ depending on the timing of NO synthase (NOS) inhibition with respect to the exercise bout (i.e., administration prior to vs. during exercise). We tested the hypothesis that, in the presence of prior cyclooxygenase inhibition (indomethacin, 5 mg/kg-1), NOS inhibition ( N G-nitro-l-arginine methyl ester, l-NAME; 10 mg/kg) administered during submaximal treadmill exercise would blunt blood flow and vascular conductance (VC) in the hindlimb muscle(s) of the rat with the greatest reductions in blood flow and VC occurring in the predominantly oxidative muscles. Adult female Wistar rats ( n = 10, age: 3–4 mo) ran on a motor-driven treadmill (20 m/min, 10% grade). Total and regional hindlimb muscle blood flow and VC were determined via radiolabeled microspheres before (control) and after l-NAME administration during exercise. l-NAME reduced ( P < 0.05) total hindlimb muscle blood flow (control: 123 ± 10, l-NAME: 103 ± 7 ml·min−1·100g−1) and VC (control: 0.95 ± 0.09, l-NAME: 0.63 ± 0.05 ml·min−1·100g−1·mmHg−1). There was a significant correlation ( r = 0.51, P < 0.05) between the absolute reductions in VC after l-NAME and the percent sum of type I and IIa fibers in the individual muscles and muscle parts; however, there was no correlation ( P = 0.62) when expressed as blood flow. Surprisingly, the highly oxidative muscles demonstrated a marked ability to maintain oxygen delivery, which differs substantially from previous reports of l-NAME infusion prior to exercise in these muscles. The demonstration that NO is an important regulator of blood flow and VC in the rat hindlimb during treadmill exercise, but that the fiber-type dependency of NO is altered markedly when NOS inhibition is performed during, vs. prior to, exercise, lends important insights into the integrated nature of vascular control during exercise.

Peripheral factors influencing expression of pressor reflex evoked by muscular contraction

1985 ◽  
Vol 58 (5) ◽  
pp. 1676-1682 ◽  
Author(s):  
G. A. Iwamoto ◽  
B. R. Botterman
Keyword(s):  
Muscle Mass ◽  
Fiber Type ◽  
Muscle Tension ◽  
Muscle Length ◽  
Muscular Contraction ◽  
Type I ◽  
Active Muscle ◽  
Type Composition ◽  
Slow Twitch Muscle ◽  
Pressor Reflex

The effect of evoked muscle tension, active muscle mass, and fiber-type composition on the pressor reflex evoked by muscular contraction was examined in decerebrate and anesthetized cats. Muscular contraction was induced by stimulating the L7 and S1 ventral roots with 0.1-ms duration pulses three times motor threshold at various frequencies. The experiments were designed to isolate the variable under study as much as possible and included the use of selectively denervated preparations to limit contractions to specific muscles. It was found that altering the evoked tension by varying the resting muscle length had commensurate effects on the pressor reflex (greater evoked tension caused a larger reflex). In addition it was found that changing the amount of active muscle mass caused similar changes in the reflex (the smaller the muscle mass, the smaller the reflex). Finally, it was found that contrary to other accounts, pressor reflexes could be evoked by activation of the slow-twitch muscle soleus, composed exclusively of red (type I) fibers.

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