A comparison of skeletal muscle morphology with training between young and old Fischer 344 rats

Mitchell, Mary L.; Byrnes, William C.; Mazzeo, Robert S.

doi:10.1016/0047-6374(91)90117-i

Cited by 31 publications

(24 citation statements)

References 36 publications

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“…For the ET, rats were given a 1-min warm-up running period at 20 cm/s. Treadmill speed was then increased to 30 cm/s on a 20°incline, and rats ran until exhaustion, which was defined as the inability of the rat to return to and maintain the pace of the treadmill for two continuous minutes (22,40,42,85). Time to exhaustion (s) was recorded.…”

Section: Animalsmentioning

confidence: 99%

Differential effects of targeted tongue exercise and treadmill running on aging tongue muscle structure and contractile properties

Kletzien

Russell

Leverson

et al. 2013

Journal of Applied Physiology

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Section: Animalsmentioning

confidence: 99%

Differential effects of targeted tongue exercise and treadmill running on aging tongue muscle structure and contractile properties

Kletzien

Russell

Leverson

et al. 2013

Journal of Applied Physiology

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“…In contrast, structural data on muscle capacity for O 2 transfer from capillary to fiber mitochondria have been contradictory. Human and/or animal studies have shown decreased (5,12,14,38), unchanged (3,4,36), or even increased (8,19,36) capillary-to-fiber number ratios in skeletal muscles with aging. Part of the discrepancies have been attributed to the fact that differences in activity levels among subjects can offset age-related effects (4), and a greater percentage of aerobic fibers (as IIb fibers are lost) can also explain greater capillarities in specific muscles with aging (36).…”

mentioning

confidence: 99%

“…Human and/or animal studies have shown decreased (5,12,14,38), unchanged (3,4,36), or even increased (8,19,36) capillary-to-fiber number ratios in skeletal muscles with aging. Part of the discrepancies have been attributed to the fact that differences in activity levels among subjects can offset age-related effects (4), and a greater percentage of aerobic fibers (as IIb fibers are lost) can also explain greater capillarities in specific muscles with aging (36). Reductions in muscle mitochondrial volume density and function are also found with age (6), but maintenance (9) or tendency toward increased mitochondrial densities (50) have also been reported, and differential mitochondrial and glycolytic enzymatic changes are known to exist among muscles and fiber types (17).…”

mentioning

confidence: 99%

Greater capillary-fiber interface per fiber mitochondrial volume in skeletal muscles of old rats

Mathieu-Costello¹,

Yan²,

Trejo-Morales³

et al. 2005

Journal of Applied Physiology

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The objective was to examine whether muscle structural capacity for O2 flux (i.e., capillary-to-fiber surface ratio) relative to fiber mitochondrial volume deteriorates with the muscle atrophy of aging in predominantly slow-(soleus, S) and fast-twitch (extensor digitorum longus, EDL) muscles of old (24 mo) and very old (35 mo) F344BN rats compared with adult (12 mo old). Wet muscle mass decreased 29% (196 Ϯ 4 to 139 Ϯ 5 mg) in S and 22% (192 Ϯ 3 to 150 Ϯ 3 mg) in EDL between 12 and 35 mo of age, without decline in body mass. Capillary density increased 65% (1,387 Ϯ 54 to 2,291 Ϯ 238 mm Ϫ2 ) in S and 130% (964 Ϯ 95 to 2,216 Ϯ 311 mm Ϫ2 ) in EDL, because of the muscle fiber atrophy, whereas capillary per fiber number remained unchanged. Altered capillary geometry, i.e., lesser contribution of tortuosity and branching to capillary length, was found in S at 35 compared with 12 and 24 mo, and not in EDL. Accounting for capillary geometry revealed 55% (1,776 Ϯ 78 to 2,750 Ϯ 271 mm Ϫ2 ) and 113% (1,194 Ϯ 112 to 2,540 Ϯ 343 mm Ϫ2 ) increases in capillary length-to-fiber volume ratio between 12 and 35 mo of age in S and EDL, respectively. Fiber mitochondrial volume density was unchanged over the same period, causing mitochondrial volume per micrometer fiber length to decrease in proportion to the fiber atrophy in both muscles. As a result of the smaller fiber mitochondrial volume in the face of the unchanged capillary-to-fiber number ratio, capillaryto-fiber surface ratio relative to fiber mitochondrial volume not only did not deteriorate, but in fact increased twofold in both muscles between 12 and 35 mo of age, independent of their different fiber type. capillary anisotropy; morphometry; ultrastructure; sarcopenia THE REDUCTION IN MUSCLE MAXIMAL capacity for aerobic work with aging is well known, and previous studies have shown alterations in both convective and diffusive components of O 2 transport in muscles. For example, reduced leg blood flow and increased leg O 2 extraction were found in older (63 Ϯ 2 yr old) compared with younger (27 Ϯ 1 yr old) endurance-trained men during submaximal exercise (42), and blood flow redistribution from highly oxidative to highly glycolytic muscles was recently demonstrated in the hindlimb of old (27-29 mo old) compared with young (6 -8 mo old) F344BN rats during submaximal exercise (37). Using an in situ pump-perfused hindlimb preparation to match convective O 2 delivery and eliminate age-related decline in blood flow, Hepple et al. (15) found a 22% decrease in the mass-specific O 2 uptake of the distal hindlimb in late middle aged (28 -39 mo) compared with young adult (8 mo) F344BN rats. In contrast, structural data on muscle capacity for O 2 transfer from capillary to fiber mitochondria have been contradictory. Human and/or animal studies have shown decreased (5, 12, 14, 38), unchanged (3, 4, 36), or even increased (8, 19, 36) capillary-to-fiber number ratios in skeletal muscles with aging. Part of the discrepancies have been attributed to the fact that differences in activit...

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“…However, endurance training failed to cause capillary growth, which was classified as no increase in the capillary-to-fiber ratio, in middle-aged 40) and old rats 41) Fig when the intensity of training was moderate. In middleaged rats, moderate intensity endurance training for 6 weeks did not cause capillary growth, whereas training with L-arginine supplementation caused marked exerciseinduced capillary growth in the hind-leg muscle and heart by promoting VEGF and eNOS protein expression (Fig.…”

Section: )mentioning

confidence: 99%

Influence of amino acid supplementation on capillary growth in the heart and skeletal muscles

Suzuki

2013

JPFSM

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In recent years, many experiments have investigated the impact of dietary amino acid supplementation on improvements in muscle strength and endurance capacity. However, it is unclear whether this supplementation causes vascular remodelling in skeletal muscle. This review focused on the effects of L-arginine and/or L-ornithine supplementation on capillary growth in cardiac and skeletal muscles. Although the chronic administration of 4% L-arginine did not improve capillarization in rat cardiac and hind-leg muscles, it facilitated exerciseinduced capillary growth via vascular endothelial growth factor (VEGF) protein upregulation. In middle-aged rats, moderate intensity endurance training for 6 weeks did not cause capillary growth, whereas training with L-arginine supplementation led to an improvement in capillarization in the hind-leg muscle and left ventricle by promoting VEGF and endothelial nitric oxide synthase (eNOS) protein expression. The administration of L-arginine and L-ornithine for 6 weeks caused a marked increase in capillarization in rat skeletal muscle via the downregulation of endostatin and upregulation of VEGF-R2 protein expression. Moreover, this supplementation facilitated exercise-induced improvements in capillarization in the hind-leg muscles via the downregulation of endostatin and upregulation of VEGF and eNOS protein levels. The evidence presented in this review indicates that L-arginine and/or L-ornithine administration may facilitate capillary growth and endurance exercise capacity. Furthermore, this supplementation may be a useful therapeutic intervention for ischemic-related diseases.

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A comparison of skeletal muscle morphology with training between young and old Fischer 344 rats

Cited by 31 publications

References 36 publications

Differential effects of targeted tongue exercise and treadmill running on aging tongue muscle structure and contractile properties

Differential effects of targeted tongue exercise and treadmill running on aging tongue muscle structure and contractile properties

Greater capillary-fiber interface per fiber mitochondrial volume in skeletal muscles of old rats

Influence of amino acid supplementation on capillary growth in the heart and skeletal muscles

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