scholarly journals Effects of Caloric Restriction and Exercise Training on Skeletal Muscle Histochemistry in Aging Fischer 344 Rats

2006 ◽  
Vol 6 ◽  
pp. 1339-1349 ◽  
Author(s):  
David T. Lowenthal ◽  
Zebulon V. Kendrick ◽  
Joseph W. Starnes ◽  
Eli Carmeli
Keyword(s):  
Lifestyle Modification ◽  
Fiber Type ◽  
Periodic Acid ◽  
Succinic Dehydrogenase ◽  
Type I ◽  
Fischer 344 Rats ◽  
Fischer 344 ◽  
Muscle Histochemistry ◽  
Ad Libitum ◽  
Type I Fibers

The purpose of this study was to determine the effects of calorie restriction and exercise on hindlimb histochemistry and fiber type in Fischer 344 rats as they advanced from adulthood through senescence. At 10 months of age, animals were divided into sedentary fedad libitum, exercise (18 m/min, 8% grade, 20 min/day, 5 days/week) fedad libitum, and calorie restricted by alternate days of feeding. Succinic dehydrogenase, myosin adenosine triphosphatase (mATPase at pH 9.4), nicotine adenonine dinucleotide reductase, and Periodic Acid Shiff histochemical stains were performed on plantaris and soleus muscles. The results indicated that aging resulted in a progressive decline in plantaris Type I muscle fiber in sedentary animals, while exercise resulted in maintenance of these fibers. The percent of plantaris Type II fibers increased between 10 and 24 months of age. Exercise also resulted in a small, but significant, increase in the percentage of plantaris Type IIa fibers at 24 months of age. The soleus fiber distribution for Type I fibers was unaffected by increasing age in all groups of animals. The implications of these results suggest the implementation of exercise as a lifestyle modification as early as possible.

Neuromuscular adaptations to cross-reinnervation in 12- and 29-mo-old Fischer 344 rats

1991 ◽  
Vol 260 (1) ◽  
pp. C96-C103 ◽  
Author(s):  
K. I. Clark ◽  
T. P. White
Keyword(s):  
Fiber Type ◽  
Type I ◽  
Fischer 344 Rats ◽  
Nerve Section ◽  
Fischer 344 ◽  
Neuromuscular Adaptations ◽  
Slow Myosin Heavy Chain ◽  
Motor End Plates ◽  
Edl Muscle ◽  
Type I Fibers

The aim was to test hypotheses regarding the adaptive response of the extensor digitorum longus (EDL) muscle of 12- and 29-mo rats following denervation and cross-reinnervation by the soleus nerve. The mass of cross-reinnervated EDL muscle was 87 and 86% of self-reinnervated control values in 12-mo (99 +/- 3 mg) and 29-mo (74 +/- 3 mg) rats, respectively. Cross-reinnervated EDL fiber area was 56 and 67% of self-reinnervated values in 12-mo (1,733 +/- 253 microns 2) and 29-mo (1,264 +/- 71 microns 2) rats, respectively. Cross-reinnervation increased the density of neural contact 26% in 12-mo rats and decreased density by 50% in 29-mo animals. In 12-mo rats 17% of motor end plates (MEP) were void of terminal nerves following cross-reinnervation compared with 48% in 29-mo rats. In cross-reinnervated muscles, slow myosin heavy chain (MHC) was 65 +/- 9 and 25 +/- 3% of total MHC in 12- and 29-mo rats, respectively. The percentage of type I fibers derived histochemically was 65 +/- 8% in 12-mo rats and 18 +/- 1% in 29-mo rats. In conclusion, there is an age-associated decrease in the ability of neurons to reinnervate the MEP area after nerve section. The conversion of fiber type in innervated fibers in response to cross-reinnervation may not differ due to age.

Fiber type-specific muscle glycogen sparing due to carbohydrate intake before and during exercise

2007 ◽  
Vol 102 (1) ◽  
pp. 183-188 ◽  
Author(s):  
K. De Bock ◽  
W. Derave ◽  
M. Ramaekers ◽  
E. A. Richter ◽  
P. Hespel
Keyword(s):  
Muscle Glycogen ◽  
Glycogen Content ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Periodic Acid ◽  
Carbohydrate Intake ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Type I Fibers ◽  
Glycogen Sparing

The effect of carbohydrate intake before and during exercise on muscle glycogen content was investigated. According to a randomized crossover study design, eight young healthy volunteers ( n = 8) participated in two experimental sessions with an interval of 3 wk. In each session subjects performed 2 h of constant-load bicycle exercise (∼75% maximal oxygen uptake). On one occasion (CHO), they received carbohydrates before (∼150 g) and during (1 g·kg body weight−1·h−1) exercise. On the other occasion they exercised after an overnight fast (F). Fiber type-specific relative glycogen content was determined by periodic acid Schiff staining combined with immunofluorescence in needle biopsies from the vastus lateralis muscle before and immediately after exercise. Preexercise glycogen content was higher in type IIa fibers [9.1 ± 1 × 10−2 optical density (OD)/μm2] than in type I fibers (8.0 ± 1 × 10−2 OD/μm2; P < 0.0001). Type IIa fiber glycogen content decreased during F from 9.6 ± 1 × 10−2 OD/μm2 to 4.5 ± 1 × 10−2 OD/μm2 ( P = 0.001), but it did not significantly change during CHO ( P = 0.29). Conversely, in type I fibers during CHO and F the exercise bout decreased glycogen content to the same degree. We conclude that the combination of carbohydrate intake both before and during moderate- to high-intensity endurance exercise results in glycogen sparing in type IIa muscle fibers.

Extreme endurance training and fiber type adaptation in rat diaphragm

1989 ◽  
Vol 66 (4) ◽  
pp. 1914-1920 ◽  
Author(s):  
H. J. Green ◽  
M. J. Plyley ◽  
D. M. Smith ◽  
J. G. Kile
Keyword(s):  
Endurance Training ◽  
Fiber Type ◽  
Succinic Dehydrogenase ◽  
Diaphragm Muscle ◽  
Type I ◽  
Fiber Types ◽  
Rat Diaphragm ◽  
Oxidative Potential ◽  
Glycerophosphate Dehydrogenase ◽  
Type I Fibers

Extreme endurance training was used to investigate the adaptability of the rat diaphragm muscle fibers. During the final phase of the 14-wk training program, the animals were running for 240 min/day at an estimated requirement of 80% of pretraining maximal O2 consumption. Analysis of a sample of the costal diaphragm indicated that training resulted in a 34% reduction (P less than 0.05) in the percent distribution of type IIa fibers [27.7 +/- 1.1 vs. 18.3 +/- 2.6 (SE)] and a 15% increase (P less than 0.05) in the percent of type IIb fibers (40.0 +/- 1.2 vs. 46.1 +/- 2.4). No change (P greater than 0.05) was found in the distribution of the type I fibers (32.3 +/- 1.2 vs. 35.7 +/- 1.3). Oxidative potential as assessed with NADH-tetrazolium reductase and measured microphotometrically increased (P less than 0.05) by 19% in type I fibers but did not change in either the type IIa or type IIb fibers. No effect of training was found when a different oxidative marker, succinic dehydrogenase, was employed. Similarly glycolytic potential based on the activity of alpha-glycerophosphate dehydrogenase was not affected by training. Glycogen concentration was elevated by 60% (P less than 0.01) in type I fibers and 77% (P less than 0.01) in type IIb fibers with training but was not altered (P greater than 0.05) in type IIa fibers. Reductions (P less than 0.05) in fiber area ranging from 11 to 20% were observed in all fiber types as a result of training, whereas the number of capillaries per fiber remained static.(ABSTRACT TRUNCATED AT 250 WORDS)

Rostrocaudal pattern of fiber-type changes in an overloaded rat ankle extensor

1991 ◽  
Vol 71 (2) ◽  
pp. 558-564 ◽  
Author(s):  
P. F. Gardiner ◽  
B. J. Jasmin ◽  
P. Corriveau
Keyword(s):  
Fiber Type ◽  
Muscle Length ◽  
Similar Degree ◽  
Complex Nature ◽  
Type I ◽  
Fiber Types ◽  
Type Ii ◽  
Cross Sectional ◽  
Hypertrophic Response ◽  
Type I Fibers

Our aim was to quantify the overload-induced hypertrophy and conversion of fiber types (type II to I) occurring in the medial head of the gastrocnemius muscle (MG). Overload of MG was induced by a bilateral tenotomy/retraction of synergists, followed by 12–18 wk of regular treadmill locomotion (2 h of walking/running per day on 3 of 4 days). We counted all type I fibers and determined type I and II mean fiber areas in eight equidistant sections taken along the length of control and overloaded MG. Increase in muscle weights (31%), as well as in total muscle cross-sectional areas (37%) and fiber areas (type I, 57%; type II, 34%), attested to a significant hypertrophic response in overloaded MG. An increase in type I fiber composition of MG from 7.0 to 11.5% occurred as a result of overload, with the greatest and only statistically significant changes (approximately 70–100%) being found in sections taken from the most rostral 45% of the muscle length. Results of analysis of sections taken from the largest muscle girth showed that it significantly underestimated the extent of fiber conversion that occurred throughout the muscle as a whole. These data obtained on the MG, which possesses a compartmentalization of fiber types, support the notion that all fiber types respond to this model with a similar degree of hypertrophy. Also, they emphasize the complex nature of the adaptive changes that occur in these types of muscles as a result of overload.

Genetic and other determinants of AMP deaminase activity in healthy adult skeletal muscle

1998 ◽  
Vol 85 (4) ◽  
pp. 1273-1278 ◽  
Author(s):  
Barbara Norman ◽  
Donna K. Mahnke-Zizelman ◽  
Amy Vallis ◽  
Richard L. Sabina
Keyword(s):  
Skeletal Muscle ◽  
Enzyme Activity ◽  
Mutant Allele ◽  
Fiber Type ◽  
Type I ◽  
Training Status ◽  
Amp Deaminase ◽  
Normal Allele ◽  
Relative Percentage ◽  
Type I Fibers

AMPD1 genotype, relative fiber type composition, training status, and gender were evaluated as contributing factors to the reported variation in AMP deaminase enzyme activity in healthy skeletal muscle. Multifactorial correlative analyses demonstrate that AMPD1 genotype has the greatest effect on enzyme activity. An AMPD1 mutant allele frequency of 13.7 and a 1.7% incidence of enzyme deficiency was found across 175 healthy subjects. Homozygotes for the AMPD1 normal allele have high enzyme activities, and heterozygotes display intermediate activities. When examined according to genotype, other factors were found to affect variability as follows: AMP deaminase activity in homozygotes for the normal allele exhibits a negative correlation with the relative percentage of type I fibers and training status. Conversely, residual AMP deaminase activity in homozygotes for the mutant allele displays a positive correlation with the relative percentage of type I fibers. Opposing correlations in different homozygous AMPD1 genotypes are likely due to relative fiber-type differences in the expression of AMPD1 and AMPD3 isoforms. Gender also contributes to variation in total skeletal muscle AMP deaminase activity, with normal homozygous and heterozygous women showing only 85–88% of the levels observed in genotype-matched men.

scholarly journals Phrenic motor neuron loss in aged rats

2018 ◽  
Vol 119 (5) ◽  
pp. 1852-1862 ◽  
Author(s):  
Matthew J. Fogarty ◽  
Tanya S. Omar ◽  
Wen-Zhi Zhan ◽  
Carlos B. Mantilla ◽  
Gary C. Sieck
Keyword(s):  
Motor Neuron ◽  
Surface Area ◽  
Motor Neurons ◽  
Fiber Type ◽  
Dendritic Morphology ◽  
Diaphragm Muscle ◽  
Specific Force ◽  
Fischer 344 Rats ◽  
Fischer 344 ◽  
Age Related

Sarcopenia is the age-related reduction of muscle mass and specific force. In previous studies, we found that sarcopenia of the diaphragm muscle (DIAm) is evident by 24 mo of age in both rats and mice and is associated with selective atrophy of type IIx and IIb muscle fibers and a decrease in maximum specific force. These fiber type-specific effects of sarcopenia resemble those induced by DIAm denervation, leading us to hypothesize that sarcopenia is due to an age-related loss of phrenic motor neurons (PhMNs). To address this hypothesis, we determined the number of PhMNs in young (6 mo old) and old (24 mo old) Fischer 344 rats. Moreover, we determined age-related changes in the size of PhMNs, since larger PhMNs innervate type IIx and IIb DIAm fibers. The PhMN pool was retrogradely labeled and imaged with confocal microscopy to assess the number of PhMNs and the morphometry of PhMN soma and proximal dendrites. In older animals, there were 22% fewer PhMNs, a 19% decrease in somal surface area, and a 21% decrease in dendritic surface area compared with young Fischer 344 rats. The age-associated loss of PhMNs involved predominantly larger PhMNs. These results are consistent with an age-related denervation of larger, more fatigable DIAm motor units, which are required primarily for high-force airway clearance behaviors. NEW & NOTEWORTHY Diaphragm muscle sarcopenia in rodent models is well described in the literature; however, the relationship between sarcopenia and frank phrenic motor neuron (MN) loss is unexplored in these models. We quantify a 22% loss of phrenic MNs in old (24 mo) compared with young (6 mo) Fischer 344 rats. We also report reductions in phrenic MN somal and proximal dendritic morphology that relate to decreased MN heterogeneity in old compared with young Fischer 344 rats.

Changes in skeletal muscle biochemistry and histology relative to fiber type in rats with heart failure

1997 ◽  
Vol 83 (4) ◽  
pp. 1291-1299 ◽  
Author(s):  
Michael D. Delp ◽  
Changping Duan ◽  
John P. Mattson ◽  
Timothy I. Musch
Keyword(s):  
Myocardial Infarction ◽  
Heart Failure ◽  
Skeletal Muscle ◽  
Enzyme Activities ◽  
Fiber Type ◽  
Left Ventricular ◽  
Type I ◽  
Fiber Composition ◽  
Muscle Biochemistry ◽  
Type I Fibers

Delp, Michael D., Changping Duan, John P. Mattson, and Timothy I. Musch. Changes in skeletal muscle biochemistry and histology relative to fiber type in rats with heart failure. J. Appl. Physiol. 83(4): 1291–1299, 1997.—One of the primary consequences of left ventricular dysfunction (LVD) after myocardial infarction is a decrement in exercise capacity. Several factors have been hypothesized to account for this decrement, including alterations in skeletal muscle metabolism and aerobic capacity. The purpose of this study was to determine whether LVD-induced alterations in skeletal muscle enzyme activities, fiber composition, and fiber size are 1) generalized in muscles or specific to muscles composed primarily of a given fiber type and 2) related to the severity of the LVD. Female Wistar rats were divided into three groups: sham-operated controls ( n = 13) and rats with moderate ( n = 10) and severe ( n = 7) LVD. LVD was surgically induced by ligating the left main coronary artery and resulted in elevations ( P < 0.05) in left ventricular end-diastolic pressure (sham, 5 ± 1 mmHg; moderate LVD, 11 ± 1 mmHg; severe LVD, 25 ± 1 mmHg). Moderate LVD decreased the activities of phosphofructokinase (PFK) and citrate synthase in one muscle composed of type IIB fibers but did not modify fiber composition or size of any muscle studied. However, severe LVD diminished the activity of enzymes involved in terminal and β-oxidation in muscles composed primarily of type I fibers, type IIA fibers, and type IIB fibers. In addition, severe LVD induced a reduction in the activity of PFK in type IIB muscle, a 10% reduction in the percentage of type IID/X fibers, and a corresponding increase in the portion of type IIB fibers. Atrophy of type I fibers, type IIA fibers, and/or type IIB fibers occurred in soleus and plantaris muscles of rats with severe LVD. These data indicate that rats with severe LVD after myocardial infarction exhibit 1) decrements in mitochondrial enzyme activities independent of muscle fiber composition, 2) a reduction in PFK activity in type IIB muscle, 3) transformation of type IID/X to type IIB fibers, and 4) atrophy of type I, IIA, and IIB fibers.

Gene Polymorphisms and Fiber-Type Composition of Human Skeletal Muscle

2012 ◽  
Vol 22 (4) ◽  
pp. 292-303 ◽  
Author(s):  
Ildus I. Ahmetov ◽  
Olga L. Vinogradova ◽  
Alun G. Williams
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Fiber Types ◽  
Fiber Type Composition ◽  
Type Composition ◽  
Type I Fibers

The ability to perform aerobic or anaerobic exercise varies widely among individuals, partially depending on their muscle-fiber composition. Variability in the proportion of skeletal-muscle fiber types may also explain marked differences in aspects of certain chronic disease states including obesity, insulin resistance, and hypertension. In untrained individuals, the proportion of slow-twitch (Type I) fibers in the vastus lateralis muscle is typically around 50% (range 5–90%), and it is unusual for them to undergo conversion to fast-twitch fibers. It has been suggested that the genetic component for the observed variability in the proportion of Type I fibers in human muscles is on the order of 40–50%, indicating that muscle fiber-type composition is determined by both genotype and environment. This article briefly reviews current progress in the understanding of genetic determinism of fiber-type proportion in human skeletal muscle. Several polymorphisms of genes involved in the calcineurin–NFAT pathway, mitochondrial biogenesis, glucose and lipid metabolism, cytoskeletal function, hypoxia and angiogenesis, and circulatory homeostasis have been associated with fiber-type composition. As muscle is a major contributor to metabolism and physical strength and can readily adapt, it is not surprising that many of these gene variants have been associated with physical performance and athlete status, as well as metabolic and cardiovascular diseases. Genetic variants associated with fiber-type proportions have important implications for our understanding of muscle function in both health and disease.

Carnitine metabolism in human muscle fiber types during submaximal dynamic exercise

1996 ◽  
Vol 80 (3) ◽  
pp. 1061-1064 ◽  
Author(s):  
D. Constantin-Teodosiu ◽  
S. Howell ◽  
P. L. Greenhaff
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Group Formation ◽  
Free Carnitine ◽  
Muscle Fiber Types ◽  
Type I ◽  
Fiber Types ◽  
Carnitine Metabolism ◽  
Type I Fibers

The effect of prolonged exhaustive exercise on free carnitine and acetylcarnitine concentrations in mixed-fiber skeletal muscle and in type I and II muscle fibers was investigated in humans. Needle biopsy samples were obtained from the vastus lateralis of six subjects immediately after exhaustive one-legged cycling at approximately 75% of maximal O2 uptake from both the exercised and nonexercised (control) legs. In the resting (control) leg, there was no difference in the free carnitine concentration between type I and II fibers (20.36 +/- 1.25 and 20.51 +/- 1.16 mmol/kg dry muscle, respectively) despite the greater potential for fat oxidation in type I fibers. However, the acetylcarnitine concentration was slightly greater in type I fibers (P < 0.01). During exercise, acetylcarnitine accumulation occurred in both muscle fiber types, but accumulation was greatest in type I fibers (P < 0.005). Correspondingly, the concentration of free carnitine was significantly lower in type I fibers at the end of exercise (P < 0.001). The sum of free carnitine and acetylcarnitine concentrations in type I and II fibers at rest was similar and was unchanged by exercise. In conclusion, the findings of the present study support the suggestion that carnitine buffers excess acetyl group formation during exercise and that this occurs in both type I and II fibers. However, the greater accumulation of acetylcarnitine in type I fibers during prolonged exercise probably reflects the greater mitochondrial content of this fiber type.

Fiber type-specific determinants of V maxfor insulin-stimulated muscle glucose uptake in vivo

2003 ◽  
Vol 284 (3) ◽  
pp. E541-E548 ◽  
Author(s):  
Hilary Ann Petersen ◽  
Patrick T. Fueger ◽  
Deanna P. Bracy ◽  
David H. Wasserman ◽  
Amy E. Halseth
Keyword(s):  
Glucose Uptake ◽  
Fiber Type ◽  
Type I ◽  
Fiber Types ◽  
Maximal Velocity ◽  
Glucose Flux ◽  
Steady State Levels ◽  
Type I Fibers ◽  
Relationship Of

The aim of this study was to determine barriers limiting muscle glucose uptake (MGU) during increased glucose flux created by raising blood glucose in the presence of fixed insulin. The determinants of the maximal velocity ( V max) of MGU in muscles of different fiber types were defined. Conscious rats were studied during a 4 mU · kg−1 · min−1insulin clamp with plasma glucose at 2.5, 5.5, and 8.5 mM. [U-14C]mannitol and 3- O-methyl-[3H]glucose ([3H]MG) were infused to steady-state levels ( t = −180 to 0 min). These isotope infusions were continued from 0 to 40 min with the addition of a 2-deoxy-[3H]glucose ([3H]DG) infusion. Muscles were excised at t = 40 min. Glucose metabolic index (Rg) was calculated from muscle-phosphorylated [3H]DG. [U-14C]mannitol was used to determine extracellular (EC) H2O. Glucose at the outer ([G]om) and inner ([G]im) sarcolemmal surfaces was determined by the ratio of [3H]MG in intracellular to EC H2O and muscle glucose. Rg was comparable at the two higher glucose concentrations, suggesting that rates of uptake near V max were reached. In summary, by defining the relationship of arterial glucose to [G]om and [G]im in the presence of fixed hyperinsulinemia, it is concluded that 1) V max for MGU is limited by extracellular and intracellular barriers in type I fibers, as the sarcolemma is freely permeable to glucose; 2) V max is limited in muscles with predominantly type IIb fibers by extracellular resistance and transport resistance; and 3) limits to Rg are determined by resistance at multiple steps and are better defined by distributed control rather than by a single rate-limiting step.

Sign in / Sign up

Export Citation Format

Share Document