Effect of sex and exogenous porcine somatotropin on longissimus muscle fiber characteristics of growing pigs.

1990 ◽  
Vol 68 (4) ◽  
pp. 1176-1181 ◽  
Author(s):  
M. B. Solomon ◽  
R. G. Campbell ◽  
N. C. Steele
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Live Weight ◽  
Growing Pigs ◽  
Fiber Types ◽  
Longissimus Muscle ◽  
Meat Tenderness ◽  
Giant Fiber ◽  
Porcine Somatotropin ◽  
Dose Levels

Abstract Thirty-seven pigs with an initial live weight of 60 kg were used to investigate the effects of daily exogenous porcine somatotropin (pST) administration at two dose levels (0 and 100 µg·kg−1·d−1) for a 31-d period on muscle fiber characteristics and meat tenderness of boars, gilts and barrows. Excipient boars and gilts had more αW and fewer αR fibers than did those receiving pST. The percentage of muscle fiber type for barrows was not affected by pST treatment. The administration of pST resulted in an increase in muscle fiber size for all three fiber types in all three sexes, but these changes were of greater magnitude in barrows (31.8%) and gilts (27.8%) than in boars (9.3%). Somatotropin negated the intrinsic sex effect differences in fiber area of the pigs. There was no difference in tenderness among excipient boars, barrows and gilts; however, with the inclusion of pST, shear force decreased in boars and gilts and increased in barrows. A high proportion of the pST-treated pigs contained giant fibers in the longissimus muscle. Furthermore, a small proportion of the pST-treated pigs exhibited pale, soft, exudative muscle. Whether the giant fiber anomalies occurred through increased muscle activity or from fibers undergoing degenerative changes was not determined.

Fiber-type proportions and diameters in the longissimus muscle of beef heifers undergoing catch-up (compensatory) growth

1991 ◽  
Vol 71 (4) ◽  
pp. 1031-1035 ◽  
Author(s):  
E. Yambayamba ◽  
M. A. Price
Keyword(s):  
Muscle Fiber ◽  
Compensatory Growth ◽  
Fiber Type ◽  
Feed Restriction ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Longissimus Muscle ◽  
Slaughter Weight ◽  
Ad Libitum ◽  
Ad Libitum Feeding

Fifty-three Hereford crossbred heifers (211 ± 28(mean ± SD) kg, 197 ± 13 d of age at day 1) were used to study the effects of mild, chronic feed restriction followed by refeeding on some longissimus muscle fiber characteristics. Five animals were slaughtered on day 1 for analysis of initial muscle fiber characteristics. The remaining 48 animals were randomly penned in groups of 6 and assigned to treatments as follows: three pens to ad libitum feeding; three pens to 2 mo of feed restriction followed by refeeding, and two pens to 4 mo of feed restriction followed by refeeding. Animals in one ad libitum and one restricted pen were slaughtered after 2 mo and those in one pen from each treatment after 4 mo, and the remainder at the final slaughter weight of about 410 kg. Two months of feed restriction had no effect on the proportions of longissimus muscle fiber-types, "red" (βR), "white" (αW), and "intermediate" (αR), but fiber diameters were smaller (P < 0.05) in the restricted than in the ad-libitum-fed animals. Four months of feed restriction was associated with a relatively higher (P < 0.05) proportion of βR fibers and lower (P < 0.05) proportion of αW fibers than ad libitum feeding. Muscle fiber diameters were larger (P < 0.05) in the ad-libitum-fed than in the restricted heifers. No significant feeding treatment differences were found in fiber-type proportions or fiber diameters at the final slaughter weight. Key words: Heifers, feed restriction, realimentation, muscle fibers, fiber-type, compensatory growth

Effect of Feed Intake and Exogenous Porcine Somatotropin on Longissimus Muscle Fiber Characteristics of Pigs Weighing 55 Kilograms Live Weight

1988 ◽  
Vol 66 (12) ◽  
pp. 3279 ◽  
Author(s):  
M. B. Solomon ◽  
R. G. Campbell ◽  
N. C. Steele ◽  
T. J. Caperna ◽  
J. P. McMurtry
Keyword(s):  
Muscle Fiber ◽  
Feed Intake ◽  
Live Weight ◽  
Longissimus Muscle ◽  
Porcine Somatotropin

Blood flow to different skeletal muscle fiber types during contraction

1983 ◽  
Vol 245 (2) ◽  
pp. H265-H275 ◽  
Author(s):  
B. G. Mackie ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Oxidative Capacity ◽  
Skeletal Muscle Fiber ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Blood Flows ◽  
Fast Twitch

Blood flow to fast-twitch red (FTR), fast-twitch white (FTW), and slow-twitch red (STR) muscle fiber sections of the gastrocnemius-plantaris-soleus muscle group was determined using 15 +/- 3-microns microspheres during in situ stimulation in pentobarbital-anesthetized rats. Steady-state blood flows were assessed during the 10th min of contraction using twitch (0.1, 0.5, 1, 3, and 5 Hz) and tetanic (7.5, 15, 30, 60, and 120/min) stimulation conditions. In addition, an earlier blood flow determination was begun at 3 min (twitch series) or at 30 s (tetanic series) of stimulation. Blood flow was highest in the FTR (220-240 ml X min-1 X 100 g-1), intermediate in the STR (140), and lowest in the FTW (70-80) section during tetanic contraction conditions estimated to coincide with the peak aerobic function of each fiber type. These blood flows are fairly proportional to the differences in oxidative capacity among fiber types. Further, their absolute values are similar to those predicted from the relationship between blood flow and oxidative capacity found by others for dog and cat muscles. During low-frequency contraction conditions, initial blood flow to the FTR and STR sections were excessively high and not dependent on contraction frequency. However, blood flows subsequently decreased to values in keeping with the relative energy demands. In contrast, FTW muscle did not exhibit this time-dependent relative hyperemia. Thus, besides the obvious quantitative differences between skeletal muscle fiber types, there are qualitative differences in blood flow response during contractions. Our findings establish that, based on fiber type composition, a heterogeneity in blood flow distribution can occur within a whole muscle during contraction.

scholarly journals Influence of feeding regime and finishing system on lamb muscle fiber and meat quality

2009 ◽  
Vol 38 (11) ◽  
pp. 2204-2210 ◽  
Author(s):  
Sarita Bonagurio Gallo ◽  
Edson Ramos de Siqueira ◽  
Eduardo Francisquine Delgado ◽  
Maeli Dal Pai Silva ◽  
Gilberto Teixeira da Rosa
Keyword(s):  
Meat Quality ◽  
Muscle Fiber ◽  
Live Weight ◽  
Nutritional Supplement ◽  
Fiber Types ◽  
Post Mortem ◽  
Fiber Morphology ◽  
Complete Diet ◽  
Weaning Age ◽  
Meat Ph

The study verified the influence of different nutritional levels of the dams, before parturition, the weaning age of the lambs and the finishing system on lamb muscle fiber morphology and meat quality. Ile-de-France × Bergamacia crossbred dams grazing on natural grassland were divided into two groups: 1) nutritional supplement 30 days before the parturition (SUPL), and 2) no nutritional supplement (NS). These groups were further subdivided by weaning age of the lambs, which corresponded to either 45 or 60 days. The weaned lambs from each of the previous groups were also divided into different finishing systems: confined and fed a complete diet (CD), confined and fed hay (H) and kept on grassland (P). The lambs were slaughtered at 30 kg live weight (CD and P), or at 150 days of age (H). The carcasses were cooled at 4ºC/24h. The analyzed variables were: longissimus dorsi muscle fiber morphophysiology, post mortem myofibrillar fragmentation (at 0, 3 and 7 days post mortem), meat pH and temperature. There was no effect of supplementation of dams or weaning age of the lambs for the evaluated variables. The frequency of slow-oxidative (SO), fast-oxidative-glycolytic (FOG) and fast-glycolytic (FG) muscle fiber types was not altered by the treatments, but the fiber cross-sectional area was smaller for the lambs finished only on hay, and the meat pH values and temperature were lower and the myofibrill fragment dimensions were smaller. As time maturation increased from 0 to 3 and 7 days post mortem, there was a decrease in the length of the myofibrill fragments. The diet of the lambs which were maintained confined and fed only with hay was nutritionally inferior when compared with all the others, and this changed the quality of the meat compared to the finishing systems on grassland or confined and fed complete diet.

Human Skeletal Muscle Fiber Types: Delineation, Development, and Distribution

1997 ◽  
Vol 22 (4) ◽  
pp. 307-327 ◽  
Author(s):  
Robert S. Staron
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Skeletal Muscle Fiber ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Key Words Aging ◽  
Fiber Number ◽  
Human Limb

This brief review attempts to summarize a number of studies on the delineation, development, and distribution of human skeletal muscle fiber types. A total of seven fiber types can be identified in human limb and trunk musculature based on the pH stability/ability of myofibrillar adenosine triphosphatase (mATPase). For most human muscles, mATPase-based fiber types correlate with the myosin heavy chain (MHC) content. Thus, each histochemically identified fiber has a specific MHC profile. Although this categorization is useful, it must be realized that muscle fibers are highly adaptable and that innumerable fiber type transients exist. Also, some muscles contain specific MHC isoforms and/or combinations that do not permit routine mATPase-based fiber typing. Although the major populations of fast and slow are, for the most part, established shortly after birth, subtle alterations take place throughout life. These changes appear to relate to alterations in activity and/or hormonal levels, and perhaps later in life, total fiber number. Because large variations in fiber type distribution can be found within a muscle and between individuals, interpretation of data gathered from human muscle is often difficult. Key words: aging, myosin heavy chains, myogenesis, myofibrillar adenosine triphosphate

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.

Metabolic variation among alpha-motoneurons innervating different muscle-fiber types. I. Oxidative enzyme activity

1984 ◽  
Vol 51 (3) ◽  
pp. 529-537 ◽  
Author(s):  
D. W. Sickles ◽  
T. G. Oblak
Keyword(s):  
Optical Density ◽  
Muscle Fiber ◽  
Enzyme Activities ◽  
Tibialis Anterior ◽  
Fiber Type ◽  
Ventral Horn ◽  
Oxidative Enzyme ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Fast Twitch

We have examined the oxidative metabolism of rat alpha-motoneurons innervating muscles composed predominantly of one muscle-fiber type. Intramuscular injections of horseradish peroxidase (HRP) into the tensor fasciae latae (TFL) (approximately 94% fast-twitch glycolytic fibers, FG), tibialis anterior (TA) (approximately 66% fast-twitch oxidative-glycolytic, FOG; 32% FG), and soleus (SOL) (approximately 84% slow-twitch oxidative, SO) muscles permitted identification of motoneurons innervating these muscles. gamma-Motoneurons (less than 25-micron average soma diameter) were eliminated from the sampling. The alpha-motoneurons innervating the TFL were considered as FG, those innervating the tibialis anterior as FOG, and those of the soleus as SO. Alternate 5-micron serial cryostat sections were processed for HRP and nicotinamide adenine dinucleotide-diapharase (NADH-D) (oxidative enzyme) activities. Controls were included to assure reliability of reaction product quantitation. Motoneuron pools of each muscle were characterized by their shape and location within the ventral horn. Cells identified on HRP sections as innervating each of the muscles were located on sections processed for NADH-D activity. The optical density of motoneurons in sections processed for NADH-D activity was measured with a Zeiss Zonax MPM 03 microdensitometer. The mean relative NADH-D activities (optical density) of alpha-motoneurons innervating the TFL (FG), TA (FOG), and SOL(SO) muscles were 0.261, 0.305, and 0.447, respectively. Although some overlap in distribution of enzyme activities was observed, statistical analysis indicated significant differences between the NADH-D activities of each type of alpha-motoneuron. This is the first report of any metabolic difference in alpha-motoneurons belonging to different motor-unit types.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle fiber types and size in trained and untrained muscles of elite athletes

1985 ◽  
Vol 59 (6) ◽  
pp. 1716-1720 ◽  
Author(s):  
P. A. Tesch ◽  
J. Karlsson
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Deltoid Muscle ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Relative Distribution ◽  
Long Distance ◽  
Tissue Samples ◽  
Greco Roman

Tissue samples were obtained from vastus lateralis and deltoid muscles of physical education students (n = 12), Greco-Roman wrestlers (n = 8), flat-water kayakers (n = 9), middle- and long-distance runners (n = 9), and olympic weight and power lifters (n = 7). Histochemical stainings for myofibrillar adenosinetriphosphatase and NADH-tetrazolium reductase were applied to assess the relative distribution of fast-twitch and slow-twitch (ST) muscle fiber types and fiber size. The %ST was not different in the vastus (mean SD 48 +/- 14) and deltoid (56 +/- 13) muscles. The %ST was higher (P less than 0.001), however, in the deltoid compared with vastus muscle of kayakers. This pattern was reversed in runners (P less than 0.001). The %ST of the vastus was higher (P less than 0.001) in runners than in any of the other groups. The %ST of the deltoid muscle was higher in kayakers than in students, runners (P less than 0.001), and lifters (P less than 0.05). The mean fiber area and the area of ST fibers were greater (P less than 0.01) in the vastus than the deltoid muscle. Our data show a difference in fiber type distribution between the trained and nontrained muscles of endurance athletes. This pattern may reflect the adaptive response to long-term endurance training.

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