Elevated interstitial fluid volume in rat soleus muscles by hindlimb unweighting

Kandarian, Susan C.; Boushel, Robert; Schulte, Lars

doi:10.1152/jappl.1991.71.3.910

Cited by 36 publications

(24 citation statements)

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“…For example; the soleus muscle wet weight was 56% of control while the soleus slow fibres were 44% of control, the plantaris muscle wet weight was within control range while the plantaris fast fibres were 70% of control values. These differences may be due to an increase in the interstitial fluid of the muscle (Kandarian et al, 1991) and/or an increase in the amount of muscle connective tissue (Hauschka et al, 1987), both of which have been reported following suspension. Because of such changes, the whole muscle wet weight will not accurately reflect the degree of atrophy in the individual fibres.…”

Section: Discussionmentioning

confidence: 95%

Cytoplasm-to-myonucleus ratios in plantaris and soleus muscle fibres following hindlimb suspension

Kasper

Lin

1996

J Muscle Res Cell Motil

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In multinucleated skeletal muscle fibres the size of the cytoplasmic volume-to-myonucleus ratio is related to the myosin heavy chain phenotype, with the ratio being larger in those fibres expressing the fast myosin heavy chain phenotype. It is unknown, however, whether this ratio is modulated during muscle fibre adaptation, such as that which occurs following muscle unloading. In this study the relationship between cross sectional area, myonuclear number and myosin type, in single fibres from the plantaris and soleus muscles of adult rats following 28 days of hindlimb suspension was examined. Each fibre was cut transversely into two segments; one segment was used for immunohistochemical identification of myosin type, the other for determination of cross sectional area and myonuclei number. Single fibre analysis revealed significant atrophy of both plantaris fast and soleus slow fibres; the mean cross sectional area (microns2) of these fibres, 3104 +/- 183 and 2082 +/- 107 (mean +/- SE), being 70 and 45%, respectively, of control means. The decreases in cross sectional area were not accompanied by corresponding decreases in the number of myonuclei (myonuclei/mm); in plantaris fast fibres the mean myonuclei counts were within the control range (88 +/- 8 (hindlimb suspension), 76 +/- 7 (control), in soleus slow fibres the counts were significantly increased (185 +/- 12 (hindlimb suspension), 154 +/- 11 (control)). The changes resulted in a significant decrease in the cytoplasmic volume-to-myonucleus ratio (microns3 x 10(3) for both fibre types; the mean ratios of 39 +/- 3 and 12 +/- 1, were 60% and 36% of control means for the plantaris fast and soleus slow fibres, respectively. These results indicate that following hindlimb suspension atrophy of muscle fibres the myonuclei numbers remain constant or increase and, hence, the effective cytoplasmic-to-myonucleus ratio is decreased. Further, the decreased changes are significantly greater in soleus slow than plantaris fast fibres.

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Section: Discussionmentioning

confidence: 95%

Cytoplasm-to-myonucleus ratios in plantaris and soleus muscle fibres following hindlimb suspension

Kasper

Lin

1996

J Muscle Res Cell Motil

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“…Increased extramyocyte space with aging may be caused by increased connective tissue, increased fat, and increased fluid volume in both rodents and humans (Hatakenaka et al, 2001;Kandarian et al, 1991;Lexell et al, 1988;Payne et al, 2003). While increased connective tissue, water, and fat are all potential contributors in increased extramyocyte space, the large degree (3.9 fold) of elevated extramyocyte space in OAL compared with YAL suggests a potential contribution of connective tissue including the endomysium and perimysium.…”

Section: Discussionmentioning

confidence: 99%

Lifelong exercise and mild (8%) caloric restriction attenuate age-induced alterations in plantaris muscle morphology, oxidative stress and IGF-1 in the Fischer-344 rat

Kim

Kwak

Leeuwenburgh

et al. 2008

Experimental Gerontology

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Muscle atrophy is a highly prevalent condition among older adults, and results from reduced muscle mass and fiber cross-sectional area. Resistive exercise training and moderate (30-40%) caloric restriction may reduce the rate of sarcopenia in animal models. We tested the hypothesis that lifelong, voluntary exercise combined with mild (8%) caloric restriction would attenuate the reduction of muscle fiber cross-sectional area in the rat plantaris. Fischer-344 rats were divided into: young adults (6 mo.) fed ad libitum (YAL); 24 mo. old fed ad libitum (OAL); 24 mo. old on 8% caloric restriction (OCR); lifelong wheel running with 8% CR (OExCR). Plantaris fiber cross-sectional area was significantly lower in OAL than YAL (−27%), but protected in OCR and OExCR, while mass/body mass ratio was preserved in OExCR only. Furthermore, 8% CR and lifelong wheel running attenuated the age-induced increases in extramyocyte space and connective tissue. Citrate synthase activity decreased with age, but was not significantly protected in OCR and OExCR. Total hydroperoxides were higher in OAL than YAL, but were not elevated in OExCR, with no change in MnSOD. IGF-1 levels were lower in OAL (−57%) than YAL, but partially protected in the OExCR group (+51%).

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“…PLAN) versus dorsiflexor muscles (e.g. EDL) [Riley et al, 1990a;Steffen et al, 1990;Diffee et al, 1991;Kandarian et al, 1991;Apseloff et al, 1993;Stump et al, 1997;Thompson et al, 1998]. Younger animals appear to have faster rates of atrophy in response to HLS.…”

Section: Effects Of Hindlimb Suspension In Mature Male Ratsmentioning

confidence: 99%

Muscle-Specific Effects of Hindlimb Suspension and Clenbuterol in Mature Male Rats

Wineski

Deutsch²,

Abukhalaf³

et al. 2002

Cells Tissues Organs

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Anabolic agents are useful tools for probing the mechanisms by which muscle fibers perceive and respond to disuse. β₂-Adrenergic agonists exert protective, and/or reparative, effects on atrophying muscle tissue. The effects of one such agent, clenbuterol (Cb), were examined on muscle mass, total protein content, and myofibrillar protein content in selected hindlimb muscles [adductor longus (ADL), extensor digitorum longus (EDL), plantaris (PLAN), soleus (SOL)] of mature male rats, under different loading conditions. Pair-fed rats were divided into four experimental groups: vehicle- and Cb-treated nonsuspended, vehicle- and Cb-treated hindlimb suspended (HLS). Experiments lasted 14 days, during which the rats received subcutaneous injections of 1 mg/kg Cb or 1 ml/kg vehicle. HLS induced significant atrophy in all muscles, except the EDL, in a generally fiber type-related pattern. However, myofibrillar protein content was affected in a more regional pattern. Cb treatment of nonsuspended rats induced hypertrophy in all muscles, in a generally uniform pattern. However, myofibrillar protein content was affected in a more fiber type-related pattern. Cb treatment of HLS rats reduced or eliminated HLS-induced atrophy in all muscles, in a muscle-specific pattern. Overall, the ADL and SOL were most susceptible to HLS-induced atrophy. The PLAN had the greatest magnitude of Cb-induced sparing of atrophy. The results show that, in mature male rats, Cb exerts anabolic effects that are load-dependent and muscle-specific. Responses to this drug cannot be reliably predicted by fiber-type composition alone.

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Elevated interstitial fluid volume in rat soleus muscles by hindlimb unweighting

Cited by 36 publications

References 0 publications

Cytoplasm-to-myonucleus ratios in plantaris and soleus muscle fibres following hindlimb suspension

Cytoplasm-to-myonucleus ratios in plantaris and soleus muscle fibres following hindlimb suspension

Lifelong exercise and mild (8%) caloric restriction attenuate age-induced alterations in plantaris muscle morphology, oxidative stress and IGF-1 in the Fischer-344 rat

Muscle-Specific Effects of Hindlimb Suspension and Clenbuterol in Mature Male Rats

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