Capillarity and fiber types in the cremaster muscle of rat and hamster

1983 ◽  
Vol 245 (2) ◽  
pp. H368-H374 ◽  
Author(s):  
I. H. Sarelius ◽  
L. C. Maxwell ◽  
S. D. Gray ◽  
B. R. Duling
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Succinic Dehydrogenase ◽  
Capillary Density ◽  
Type I ◽  
Fiber Types ◽  
Cremaster Muscle ◽  
Muscle Area ◽  
Cross Sectional

We determined muscle fiber type and capillarity in cremaster muscle samples from rats and hamsters of different ages. Histochemical estimation of oxidative capacity was made from the activity of either nicotinamide dinucleotide tetrazolium reductase (NADH-TR) or succinic dehydrogenase (SDH), and fibers were termed fast or slow from myofibrillar ATPase activity. Fibers were classified as type I (low ATPase, high NADH-TR/SDH), type IIa (high ATPase, high SDH/NADH-TR), type IIb (high ATPase, low SDH/NADH-TR), or type IIc (no acid reversal of ATPase, high NADH-TR). Type IIb fibers accounted for 60-80% of the muscle area in both species at all ages. The principal change with maturation was muscle fiber hypertrophy. Mean cross-sectional fiber area increased from 488 +/- 70 (SE) and 453 +/- 19 micron2 in young hamsters and rats, respectively, to 1,255 +/- 99 and 1,540 +/- 101 micron2 in adults. Capillary density (no. of capillaries/mm2 tissue) paralleled fiber hypertrophy; it decreased significantly with maturation from 684 +/- 60 (SE) to 228 +/- 26/mm2 in hamsters and from 341 +/- 15 to 213 +/- 15/mm2 in rats. In vitro estimates of capillary density are compared with previously obtained in vivo data (31), and sources of error are identified. We conclude that reported differences in microvascular function in the cremaster muscle in vivo during maturation or between species cannot be ascribed to changes in muscle composition.

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.

Capillary and size interrelationships in developing rat diaphragm, EDL, and soleus muscle fiber types

1989 ◽  
Vol 256 (1) ◽  
pp. C50-C58 ◽  
Author(s):  
D. Smith ◽  
H. Green ◽  
J. Thomson ◽  
M. Sharratt
Keyword(s):  
Muscle Fiber ◽  
Time Course ◽  
Fiber Type ◽  
Capillary Density ◽  
Muscle Fiber Types ◽  
Type I ◽  
Fiber Types ◽  
Fiber Area ◽  
Male Wistar Rats ◽  
Type I Fibers

The effects of maturation on the interrelationship between skeletal muscle fiber area and capillarization was investigated in specific fiber types (I, IIa, IIb, IIc) of male Wistar rats at seven developmental periods ranging from 8 to 85 days postnatal. Fiber type specific developmental properties were compared in three different muscles, the diaphragm (DIA), extensor digitorum longus (EDL), and soleus (SOL), which are known to differ widely in function. All fiber types in each of the three muscles examined exhibited large increases in area (FA), the magnitude and time course of the increase being related to both the type of fiber and the muscle in which the fiber was located. For type I fibers, areas increased from 3- to 18-fold (SOL greater than EDL greater than DIA), whereas in type IIa fibers, area increased ranged between 5- to 11-fold (SOL greater than EDL greater than DIA). Growth rates in IIb fibers were more homogeneous between muscles ranging from 11- to 14-fold. Capillarization, as indicated by the capillary contacts per fiber (CC), increased in all fiber types regardless of muscle origin. These increases ranged between 1.7- and 2.2-fold for type I fibers, between 2.4- and 2.5-fold for type IIa fibers, and between 2.0- and 3.0-fold for type IIb fibers. In general, capillary density expressed as the ratio of the number of capillary contacts divided by the fiber area (CC/FA) progressively declined in all fiber types with age. The rate of the decline in CC/FA was mediated in large part by the changes in fiber area.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle fiber hypertrophy, hyperplasia, and capillary density in college men after resistance training

1996 ◽  
Vol 81 (5) ◽  
pp. 2004-2012 ◽  
Author(s):  
G. E. McCall ◽  
W. C. Byrnes ◽  
A. Dickinson ◽  
P. M. Pattany ◽  
S. J. Fleck
Keyword(s):  
Resistance Training ◽  
Muscle Fiber ◽  
Biceps Brachii ◽  
College Men ◽  
Capillary Density ◽  
Type I ◽  
Muscle Area ◽  
Cross Sectional ◽  
Fiber Number ◽  
Muscle Groups

McCall, G. E., W. C. Byrnes, A. Dickinson, P. M. Pattany, and S. J. Fleck. Muscle fiber hypertrophy, hyperplasia, and capillary density in college men after resistance training. J. Appl. Physiol. 81(5): 2004–2012, 1996.—Twelve male subjects with recreational resistance training backgrounds completed 12 wk of intensified resistance training (3 sessions/wk; 8 exercises/session; 3 sets/exercise; 10 repetitions maximum/set). All major muscle groups were trained, with four exercises emphasizing the forearm flexors. After training, strength (1-repetition maximum preacher curl) increased by 25% ( P < 0.05). Magnetic resonance imaging scans revealed an increase in the biceps brachii muscle cross-sectional area (CSA) (from 11.8 ± 2.7 to 13.3 ± 2.6 cm2; n = 8; P < 0.05). Muscle biopsies of the biceps brachii revealed increases ( P < 0.05) in fiber areas for type I (from 4,196 ± 859 to 4,617 ± 1,116 μm2; n = 11) and II fibers (from 6,378 ± 1,552 to 7,474 ± 2,017 μm2; n = 11). Fiber number estimated from the above measurements did not change after training (293.2 ± 61.5 × 103 pretraining; 297.5 ± 69.5 × 103 posttraining; n = 8). However, the magnitude of muscle fiber hypertrophy may influence this response because those subjects with less relative muscle fiber hypertrophy, but similar increases in muscle CSA, showed evidence of an increase in fiber number. Capillaries per fiber increased significantly ( P < 0.05) for both type I (from 4.9 ± 0.6 to 5.5 ± 0.7; n = 10) and II fibers (from 5.1 ± 0.8 to 6.2 ± 0.7; n = 10). No changes occurred in capillaries per fiber area or muscle area. In conclusion, resistance training resulted in hypertrophy of the total muscle CSA and fiber areas with no change in estimated fiber number, whereas capillary changes were proportional to muscle fiber growth.

Early changes in fiber profile and capillary density in long-term stimulated muscles

1982 ◽  
Vol 243 (4) ◽  
pp. H528-H535 ◽  
Author(s):  
O. Hudlicka ◽  
L. Dodd ◽  
E. M. Renkin ◽  
S. D. Gray
Keyword(s):  
Capillary Flow ◽  
Fiber Type ◽  
Succinic Dehydrogenase ◽  
Capillary Density ◽  
Fiber Types ◽  
Type Conversion ◽  
Cross Sectional ◽  
Capillary Growth ◽  
Change In Mean

Predominantly fast skeletal muscles of rabbits [tibialis anterior (TA), extensor digitorum longus (EDL)] were stimulated at a frequency naturally occurring in nerves to slow muscles (10 Hz continuously) for 8 h/day for 2--4 days. Such stimulation is known to convert all glycolytic fibers to oxidative and to increase capillary density. Our aim was to study early stages of conversion to investigate the factors responsible for the changes. Staining of quick-frozen sections for myosin ATPase, succinic dehydrogenase, and alkaline phosphatase was used to study the distribution of different fiber types and to measure fiber cross-sectional areas, capillaries per square millimeter, and capillary-to-fiber ratios in each fiber category. TA but not EDL showed conversion of fast glycolytic to fast oxidative fibers after 2 days, more after 4 days of stimulation. In both muscles, the largest fast glycolytic fibers were diminished in number after stimulation. There was significant increase in total capillaries per square millimeter after 4 days and some increase after 2 days of stimulation. The increase in capillaries per square millimeter exceeded the increase in the number of fibers per square millimeter, and since there was no change in mean fiber area, the increase is attributed to capillary growth. In EDL, there was an increase in the number of capillaries supplying both fast glycolytic and fast oxidative fibers, suggesting that capillary growth precedes fiber type conversion. In TA, the number of capillaries supplying fast oxidative fibers was increased but that to fast glycolytic fibers, was not. This is consistent with capillary growth simultaneous with or following fiber conversion. In both TA and EDL the number of capillaries perfused after contraction was higher in stimulated muscles, suggesting that increased capillary flow contributed to capillary growth.

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.

Regulation of fiber size, oxidative potential, and capillarization in human muscle by resistance exercise

1999 ◽  
Vol 276 (2) ◽  
pp. R591-R596 ◽  
Author(s):  
H. Green ◽  
C. Goreham ◽  
J. Ouyang ◽  
M. Ball-Burnett ◽  
D. Ranney
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Succinic Dehydrogenase ◽  
Quadriceps Muscle ◽  
Cellular Tissue ◽  
Cross Sectional Area ◽  
Fiber Types ◽  
Sectional Area ◽  
Oxidative Potential ◽  
Cross Sectional

To examine the hypothesis that increases in fiber cross-sectional area mediated by high-resistance training (HRT) would result in a decrease in fiber capillarization and oxidative potential, regardless of fiber type, we studied six untrained males (maximum oxygen consumption, 45.6 ± 2.3 ml ⋅ kg−1 ⋅ min−1; mean ± SE) participating in a 12-wk program designed to produce a progressive hypertrophy of the quadriceps muscle. The training sessions, which were conducted 3 times/wk, consisted of three sets of three exercises, each performed for 6–8 repetitions maximum (RM). Measurements of fiber-type distribution obtained from tissue extracted from the vastus lateralis at 0, 4, 7, and 12 wk indicated reductions ( P < 0.05) in type IIB fibers (15.1 ± 2.1% vs. 7.2 ± 1.3%) by 4 wk in the absence of changes in the other fiber types (types I, IIA, and IIAB). Training culminated in a 17% increase ( P < 0.05) in cross-sectional area by 12 wk with initial increases observed at 4 wk. The increase was independent of fiber type-specific changes. The number of capillaries in contact with each fiber type increased by 12 wk, whereas capillary contacts-to-fiber area ratios remained unchanged. In a defined cross-sectional field, HRT also increased the capillaries per fiber at 12 wk. Training failed to alter cellular oxidative potential, as measured by succinic dehydrogenase (SDH) activity, regardless of fiber type and training duration. It is concluded that modest hypertrophy induced by HRT does not compromise cellular tissue capillarization and oxidative potential regardless of fiber type.

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.

Histochemical and Morphometric Evaluation of Skeletal Muscle of Cachectic Sheep

1981 ◽  
Vol 18 (3) ◽  
pp. 279-298 ◽  
Author(s):  
T. J. Hulland
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Succinic Dehydrogenase ◽  
Adult Life ◽  
Biological Behavior ◽  
Type I ◽  
Fiber Types ◽  
Type Ii ◽  
Atrophy And Hypertrophy ◽  
Type I Fibers

Skeletal muscle of sheep was examined histochemically in an attempt to define muscle fiber populations capable of distinctive biological behavior. ATPase at alkaline and acid pH, NADH-TR, and succinic dehydrogenase showed at least 12 fiber types, but only three often enough to be considered biologically important muscle fiber populations. The proportions of the three major types altered during early life, but not perceptibly during adult life. Proportions of Type I and Type II fibers were different, sometimes significantly, from breed to breed. Histochemical techniques and morphometric analyses of fiber cross-sectional area were used to study muscle fiber changes in moderate to marked cachectic atrophy. Progressive reduction of gross muscle volume was attended by complex interrelationships between the two major muscle fiber types, including alternate episodes of atrophy and hypertrophy, resulting in marked inequality of mean fiber size between the fiber types. The patterns appeared to be different but characteristic for each muscle. The usual pattern of cachectic atrophy shows atrophy resistance of Type I fibers, but here a Type II-dominant atrophy also was seen. It is concluded that the large muscle fibers often seen in advanced cachectic atrophy are those Type I fibers that are more labile in both atrophy and hypertrophy than most.

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