Skeletal muscle cytochrome c and myoglobin, endurance, and frequency of training

1981 ◽  
Vol 51 (3) ◽  
pp. 746-749 ◽  
Author(s):  
R. C. Hickson
Keyword(s):  
Skeletal Muscle ◽  
Cytochrome C ◽  
Vastus Lateralis ◽  
Training Group ◽  
Treadmill Running ◽  
Female Rats ◽  
Time To Exhaustion ◽  
Training Frequency ◽  
Muscle Types ◽  
Fast Twitch

This study was undertaken to evaluate the effects of various training frequencies on performance capacity, the mitochondrial marker cytochrome c, and myoglobin, which is responsible for storage and transport of O2, in the three types of skeletal muscle. Female rats were trained by treadmill running up to 120 min/day, either 2, 4, or 6 days/wk for 14 wk. As a result of training, exercise time to exhaustion was increased in proportion to the number of training sessions per week. Cytochrome c concentration increased (range 20–90%) as a linear function of the number of exercises per week in the fast-twitch red vastus lateralis (FTR), the slow-twitch soleus (STR), and the mixed plantaris muscles. However, the concentration of cytochrome c in fast-twitch white vastus lateralis (FTW) muscles increased to approximately the same extent (40–50%) in all training groups. The increases in myoglobin concentration (13–45%) with training were significantly related to frequency in FTR muscle but not in STR muscle. Myoglobin levels in FTW muscle remained unchanged, regardless of training group. These results provide evidence that the capacity to perform endurance exercise and the mitochondrial content of the red skeletal muscle types are directly affected by training frequency.

Reduced training frequency effects on aerobic power and muscle adaptations in rats

1984 ◽  
Vol 57 (6) ◽  
pp. 1834-1841 ◽  
Author(s):  
R. C. Hickson ◽  
S. M. Overland ◽  
K. A. Dougherty
Keyword(s):  
Skeletal Muscles ◽  
Vastus Lateralis ◽  
Female Rats ◽  
Control Group ◽  
O2 Uptake ◽  
Rate Of Increase ◽  
Training Frequency ◽  
Muscle Adaptations ◽  
Fast Twitch ◽  
Sufficient Stimulus

Female rats were exercised by swimming up to 4 h/day either 2, 4, or 6 days/wk. After 7 wk they continued to train at these frequencies or had their training reduced from 6 to 4, 2, or 0 days/wk for an additional 9 wk. Ventricular weights and maximum O2 uptake (VO2max) were increased by 5-10% after training 2 days/wk, 15-17% after 4 days/wk, and 25-30% after 6 days/wk. Following reduced training, VO2max was similar when the 4- or 2-day/wk reduced training groups are compared with their 4- or 2-day/wk continued training counterparts. In contrast, VO2max was greater in the 0-day reduced than in the sedentary control group. No differences in mitochondrial markers or myoglobin content in red or mixed skeletal muscles were found between training 2 or 4 days/wk vs. reduced training at comparable frequencies. O2 uptake capacity of plantaris muscles and myoglobin concentration in fast-twitch red vastus lateralis muscles were greater in the 0-day reduced group than in the sedentary controls. These data show that VO2max and certain markers of aerobic metabolism in skeletal muscles of rats are lost at a slower rate than their rate of increase from the untrained state. However, a reduction of swimming frequency from 6 to 4 or 2 days/wk is not a sufficient stimulus to maintain VO2max, cardiac enlargement, or the increased aerobic potential of skeletal muscle at the 6-day/wk levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical adaptations in skeletal muscle of trained thyroidectomized rats

1976 ◽  
Vol 230 (5) ◽  
pp. 1194-1197 ◽  
Author(s):  
RL Terjung ◽  
JE Koerner
Keyword(s):  
Skeletal Muscle ◽  
Cytochrome C ◽  
Training Program ◽  
Muscle Fibers ◽  
Oxidative Capacity ◽  
Treadmill Running ◽  
Absolute Increase ◽  
Normal Thyroid Function ◽  
Slow Twitch ◽  
Fast Twitch

The cytochrome c concentrations of the different types of skeletal muscle of trained and nontrained normal and thyroidectomized rats were measured. Animals were trained by treadmill running 1 mph, at a 15% incline, 1 h/day, 5 days/wk for at least 12 wk. This training program induced an expected 50% increase in cytochrome c in the high-oxidative fast-twitch red (FTR) and slow-twitch red (STR) fibers and only a 25% increase in the low-oxidative fast-twitch white (FTW) fibers of the normal rats. This same training program caused a greater increase (100%) in the FTR and STR fibers of the thyroidectomized runners and a dramatic 243% increase in the FTW fiber. Even though the thyroidectomy procedure caused a reduction in oxidative capacity of all types of skeletal muscle fibers to about one-half normal, the absolute increase in cytochrome c in the muscles of the trained thyroidectomized animals was essentially the same or greater than that of the normal trained animals. These results indicate that the adaptive response to training of an increased oxidative capacity in skeletal muscle occurs in the absence of normal thyroid function. They also suggest that the exercise bouts of the thyroidectomized animals were performed with a relatively greater involvement of the FTW muscle fibers.

Acute glucocorticoid effects on glycogen utilization, O2 uptake, and endurance

1988 ◽  
Vol 64 (3) ◽  
pp. 1098-1106 ◽  
Author(s):  
E. M. Gorostiaga ◽  
S. M. Czerwinski ◽  
R. C. Hickson
Keyword(s):  
Fatty Acids ◽  
Running Economy ◽  
Treadmill Running ◽  
Female Rats ◽  
Time To Exhaustion ◽  
O2 Uptake ◽  
Carbohydrate Utilization ◽  
Plasma Fatty Acids ◽  
Fast Twitch ◽  
The Impact

This study was undertaken to determine the effects of increased substrate availability (glycogen + plasma fatty acids) by glucocorticoids on energy metabolism during exercise to exhaustion. Female rats received a single subcutaneous injection of cortisol acetate (CA) (100 mg.kg body wt-1) 21 h before treadmill running (30.8 m/min). At the start of exercise in the CA-treated rats, plasma fatty acids and liver glycogen were increased by 40%. Glycogen levels were also increased by CA treatment in slow-twitch soleus (61%), fast-twitch white vastus (38%), and fast-twitch red vastus lateralis (85%) muscles. Exercise time to exhaustion was increased by CA treatment (114 ± 5 vs. 95 ± 6 min, P less than 0.05). During the exercise, total glycogen depletion was greater in the CA-treated than in the control animals, whereas estimated relative rates of carbohydrate utilization (R = 0.90) were similar. However, while running the CA-treated group consumed 11% more O2 than the controls (P less than 0.05). These results show that a single injection of glucocorticoids is capable of improving endurance. Yet the increased O2 uptake during exercise may have minimized the impact of the initial increased availability of carbohydrates and fatty acids in prolonging exercise capacity. This decreased running economy by the CA-treated runners may be secondary to alterations in energy production or utilization.

Ammonia and IMP in different skeletal muscle fibers after exercise in rats

1980 ◽  
Vol 49 (6) ◽  
pp. 1037-1041 ◽  
Author(s):  
R. A. Meyer ◽  
G. A. Dudley ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Vastus Lateralis ◽  
Muscle Fibers ◽  
Treadmill Running ◽  
Strenuous Exercise ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Glycolytic Intermediate ◽  
Lactate Levels ◽  
Fast Twitch

Adenosine 5'-monophosphate (AMP) deamination, estimated from inosine 5'-monophosphate (IMP) accumulation, was studied in the different skeletal muscle fiber types of untrained rats anesthetized with ether immediately after 4 min of treadmill running at 45 or 60 m/min. The adenylosuccinate synthetase-inhibitor hadacidin was administered (200 mg/kg ip) before exercise to block IMP reamination and, therefore, to provide a better assessment of IMP formation. The increases in blood ammonia after exercise (2.5- and 5-fold, respectively) were highly correlated (r = 0.93) with the increases in blood lactate levels (6- and 11-fold). At both speeds, IMP increased in fast-twitch but not in slow-twitch (soleus) muscle. Of the fast muscles, the increase in IMP was greatest (up to 4 mumol/g wet wt) in the white vastus lateralis (fast twitch, glycolytic), intermediate in the plantaris (mixed fibers), and lowest in the red vastus lateralis (fast twitch, oxidative glycolytic). The increases in IMP were coincident with nearly equivalent decreases in ATP. Hadacidin treatment resulted in a greater IMP accumulation after exercise in both fast-twitch types but not in the soleus. The results indicate that fast-twitch muscle fibers, particularly the fast-twitch glycolytic fibers, are the source of the ammonia produced during strenuous exercise.

AMP deaminase binding in rat skeletal muscle after high-intensity running

1993 ◽  
Vol 74 (4) ◽  
pp. 2004-2006 ◽  
Author(s):  
K. W. Rundell ◽  
P. C. Tullson ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
High Speed ◽  
Adenine Nucleotide ◽  
Vastus Lateralis ◽  
Treadmill Running ◽  
Substrate Affinity ◽  
Amp Deaminase ◽  
Adenylate Pool ◽  
Fast Twitch

Skeletal muscle deaminates a substantial fraction of its adenylate pool to inosine 5'-monophosphate (IMP) when the rate of energy expenditure exceeds supply. How AMP deaminase is activated in vivo is unclear because the substrate affinity is quite low (Michaelis constant approximately 1–2 mM) relative to estimated concentrations of free AMP in skeletal muscle (0.2–1 microM). AMP deaminase:myosin binding causes a large increase in substrate affinity; whether this binding occurs during physiological exercise is uncertain. Exhaustive high-speed (60 m/min) treadmill exercise in rats results in an extensive depletion of adenine nucleotide and a stoichiometric accumulation of IMP (1.5–2 mumol/g) in the superficial vastus lateralis muscles (predominantly fast-twitch white). We measured AMP deaminase:myosin binding after intense exercise and found the bound fraction of AMP deaminase to be increased from 9 +/- 1% at rest to 48 +/- 4% at approximately 45 s after exercise. The extent of binding lessened during recovery from exercise, falling to 32 +/- 4% after approximately 75 s and 21 +/- 2% after approximately 105 s. This postexercise dissociation of AMP deaminase from myosin appeared to be a first-order process (approximately 50 s half time). Treadmill running that leads to deamination also results in AMP deaminase:myosin binding. Binding should activate AMP deaminase and thus favor IMP formation at low physiological concentrations of AMP.

Daily running for 2 wk and mRNAs for cytochrome c and alpha-actin in rat skeletal muscle

1989 ◽  
Vol 257 (5) ◽  
pp. C936-C939 ◽  
Author(s):  
P. R. Morrison ◽  
R. B. Biggs ◽  
F. W. Booth
Keyword(s):  
Skeletal Muscle ◽  
Cytochrome C ◽  
Training Program ◽  
Citrate Synthase ◽  
Mitochondrial Protein ◽  
Female Rats ◽  
Hindlimb Muscles ◽  
Actin Mrna ◽  
Alpha Actin ◽  
Fast Twitch

The purpose of the study was to determine whether daily running durations that were 7-14% of the durations employed in the chronic stimulation protocols (consisting of 24 h of daily indirect electrical stimulation of skeletal muscles) still resulted in increases in a mitochondrial protein mRNA. Adult female rats were run 100 min/day on motor-driven treadmills for 2 wk. Documentation that rats underwent the stated training program was obtained by a 30-41% increase in citrate synthase activity in hindlimb muscles after 2 wk of the training. Cytochrome c mRNA was increased 17-56% in hindlimb muscles after the 2-wk training program. Thus shorter durations of exercise (100 min/day rather than 24 h/day) can increase cytochrome c mRNA. alpha-Actin mRNA increased 61-62% in fast-twitch muscles in the hindlimbs of the same rats that underwent the 2 wk of run training but did not increase in the predominantly slow-twitch soleus muscle. The increase in alpha-actin mRNA was unexpected, since it is well known that this type of physical exercise does not increase the size of fast-twitch skeletal muscle.

Glutamine synthetase induction by glucocorticoids is preserved in skeletal muscle of aged rats

1996 ◽  
Vol 271 (6) ◽  
pp. E1061-E1066 ◽  
Author(s):  
D. Meynial-Denis ◽  
M. Mignon ◽  
A. Miri ◽  
J. Imbert ◽  
E. Aurousseau ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glutamine Synthetase ◽  
Skeletal Muscles ◽  
Female Rats ◽  
Mrna Levels ◽  
Aged Rats ◽  
Adult Rats ◽  
Adult Age ◽  
Slow Twitch ◽  
Fast Twitch

Glutamine synthetase (GS) is a glucocorticoid-inducible enzyme that has a key role for glutamine synthesis in muscle. We hypothesized that the glucocorticoid induction of GS could be altered in aged rats, because alterations in the responsiveness of some genes to glucocorticoids were reported in aging. We compared the glucocorticoid-induced GS in fast-twitch and slow-twitch skeletal muscles (tibialis anterior and soleus, respectively) and heart from adult (age 6-8 mo) and aged (age 22 mo) female rats. All animals received dexamethasone (Dex) in their drinking water (0.77 +/- 0.10 and 0.80 +/- 0.08 mg/day per adult and aged rat, respectively) for 5 days. Dex caused an increase in both GS activity and GS mRNA in fast-twitch and slow-twitch skeletal muscles from adult and aged rats. In contrast, Dex increased GS activity in heart of adult rats, without any concomitant change in GS mRNA levels. Furthermore, Dex did not affect GS activity in aged heart. Thus the responsiveness of GS to an excess of glucocorticoids is preserved in skeletal muscle but not in heart from aged animals.

Effects of glucocorticoids and endurance training on cytochrome oxidase expression in skeletal muscle

1994 ◽  
Vol 77 (4) ◽  
pp. 1685-1690 ◽  
Author(s):  
J. R. Marone ◽  
M. T. Falduto ◽  
D. A. Essig ◽  
R. C. Hickson
Keyword(s):  
Endurance Training ◽  
Exercise Program ◽  
Treadmill Running ◽  
Female Rats ◽  
Glucocorticoid Treatment ◽  
Subunit Mrna ◽  
Mrna Content ◽  
Muscle Groups ◽  
Coordinate Changes ◽  
Fast Twitch

This investigation was undertaken to evaluate whether the mitochondrial disfunction associated with glucocorticoid treatment is expressed at the level of cytochrome-c oxidase (COX) and whether endurance training attenuates this response. Adult female rats were administered cortisol acetate (100 mg/kg body wt) or an equal volume of the vehicle solution for 11 days. Endurance training was performed by treadmill running up to 28 m/min (with intervals at 50 m/min for 2 min every 15 min), for 90 min/day, 6 days/wk, for 8–10 wk. During hormone treatments, the training animals ran every day. Exercise prevented 43–55% of the hormone-induced atrophy in various fast-twitch muscles or muscle groups. Cortisol acetate treatment produced no significant effects on COX enzyme activities or subunit mRNA content in deep red or superficial white quadriceps or mixed plantaris muscles. The levels of COX were increased as a result of training by 70–110% in plantaris and red quadriceps muscles, but no changes were seen in white quadriceps muscles. Both nuclear-encoded (COX IV) and mitochondrial-encoded (COX III) mRNAs were increased approximately twofold by the exercise program in these same muscles. These data indicate that the impaired mitochondrial functioning associated with glucocorticoids is not observed at the COX step of electron transport. The prolonged endurance-training regimen appears to induce relatively parallel increases in COX enzyme activity and mRNA expression with coordinate changes in nuclear and mitochondrial mRNAs.

Alpha-actin and cytochrome c mRNAs in atrophied adult rat skeletal muscle

1988 ◽  
Vol 254 (5) ◽  
pp. C651-C656 ◽  
Author(s):  
P. Babij ◽  
F. W. Booth
Keyword(s):  
Skeletal Muscle ◽  
Cytochrome C ◽  
Muscle Atrophy ◽  
Weight Bearing ◽  
Skeletal Muscle Atrophy ◽  
Rna Content ◽  
Mrna Content ◽  
Fast Twitch Muscle ◽  
Alpha Actin ◽  
Fast Twitch

Specific complementary DNA (cDNA) hybridization probes were used to estimate the levels of alpha-actin and cytochrome c mRNAs and also 18S rRNA in three models of skeletal muscle atrophy. After 7 days of hindlimb suspension, or immobilization, or denervation, protein content decreased 26-32% in all muscles studied except suspended fast-twitch muscle, which lost only half as much protein. alpha-Actin mRNA content decreased 51-66% and cytochrome c mRNA content decreased 42-61% in slow- and fast-twitch muscles in all three models of atrophy. However, total RNA content did not show similar directional changes; RNA content decreased 27-44% in suspended and immobilized muscle but was unchanged in denervated fast-twitch muscle. The results were interpreted to suggest that loss of weight-bearing function of skeletal muscle is a major factor affecting the levels of alpha-actin and cytochrome c mRNAs during muscle atrophy.

Muscle blood flow during exercise in sedentary and trained hypothyroid rats

1995 ◽  
Vol 269 (6) ◽  
pp. H1949-H1954 ◽  
Author(s):  
R. M. McAllister ◽  
M. D. Delp ◽  
K. A. Thayer ◽  
M. H. Laughlin
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Citrate Synthase ◽  
Vastus Lateralis ◽  
Muscle Blood Flow ◽  
Treadmill Running ◽  
Exercise Intolerance ◽  
Vastus Lateralis Muscle ◽  
Blood Flows ◽  
Vastus Intermedius

Hypothyroidism is characterized by exercise intolerance. We hypothesized that active muscle blood flow during in vivo exercise is inadequate in the hypothyroid state. Additionally, we hypothesized that endurance exercise training would restore normal blood flow during acute exercise. To test these hypotheses, rats were made hypothyroid (Hypo) over 3-4 mo with propylthiouracil. A subset of Hypo rats was trained (THypo) on a treadmill at 30 m/min (15% grade) for 60 min/day 5 days/wk over 10-15 wk. Hypothyroidism was evidenced by approximately 80% reductions in plasma triiodothyronine levels in Hypo and THypo and by 40-50% reductions in citrate synthase activities in high oxidative muscles in Hypo compared with euthyroid (Eut) rats. Training efficacy was indicated by increased (25-100%) citrate synthase activities in muscles of THypo vs. Hypo. Regional blood flows were determined by the radiolabeled microsphere method before exercise and at 1-2 min of treadmill running at 15 m/min (0% grade). Preexercise muscle blood flows were generally similar among groups. During exercise, however, flows were lower in Hypo than in Eut for high oxidative muscles such as the red section of vastus lateralis [277 +/- 24 and 153 +/- 13 (SE) ml.min-1.100 g-1 for Eut and Hypo, respectively; P < 0.01] and vastus intermedius (317 +/- 32 and 187 +/- 20 ml.min-1.100 g-1 for Eut and Hypo, respectively; P < 0.01) muscles. Training (THypo) did not normalize these flows (168 +/- 24 and 181 +/- 24 ml.min-1.100 g-1 for red section of vastus lateralis and vastus intermedius muscles, respectively). Blood flows to low oxidative muscle, such as the white section of vastus lateralis muscle, were similar among groups (21 +/- 5, 25 +/- 4, and 34 +/- 7 ml.min-1.100 g-1 for Eut, Hypo, and THypo, respectively; P = NS). These findings indicate that hypothyroidism is associated with reduced blood flow to skeletal muscle during exercise, suggesting that impaired delivery of nutrients to and/or removal of metabolites from skeletal muscle contributes to the poor exercise tolerance characteristic of hypothyroidism.

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