Detrimental effects of reloading recovery on force, shortening velocity, and power of soleus muscles from hindlimb-unloaded rats

Widrick, Jeffrey J.; Maddalozzo, Gianni F.; Hu, Hui; Herron, Jacquelyn C.; Iwaniec, Urszula T.; Turner, Russell T.

doi:10.1152/ajpregu.00045.2008

Cited by 31 publications

(30 citation statements)

References 45 publications

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“…Indeed, due to hanging at a 30° head down position, coughing is impaired, leading to reduced clearance of inflammatory cells (45). Extreme inactivity resulted in body weight loss as previously observed (46) but this was not due to a reduction of food intake that, in fact, increased during the period of hindlimb suspension towards the levels of active mice (46). Loss of body weight was accompanied with loss of soleus and gastrocnemius mass and a pronounced loss of fat mass, which are likely due to hypermetabolism (47).…”

Section: Discussionsupporting

confidence: 71%

Interaction between Physical Activity and Smoking on Lung, Muscle, and Bone in Mice

Cielen

Maes

Heulens

et al. 2016

Am J Respir Cell Mol Biol

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Physical inactivity is an important contributor to skeletal muscle weakness, osteoporosis and weight loss in chronic obstructive pulmonary disease. However, the effects of physical inactivity, in interaction with smoking, on lung, muscle and bone are poorly understood. To address this issue, male mice were randomly assigned into an active (daily running), moderately inactive (space restriction) or extremely inactive group (space restriction followed by hindlimb suspension to mimic bed rest) during 24 weeks and simultaneously exposed to either cigarette smoke or room air. The effects of different physical activity levels and smoking status and their respective interaction were examined on lung function, body composition, in vitro limb muscle function and bone parameters. Smoking caused emphysema, reduced food intake with subsequent loss of body weight, fat, lean and muscle mass but increased trabecular bone volume. Smoking induced muscle fiber atrophy which did not result in force impairment. Moderate inactivity only affected lung volumes and compliance, whereas extreme inactivity increased lung inflammation, lowered body and fat mass, induced fiber atrophy with soleus muscle dysfunction and reduced exercise capacity and all bone parameters. When combined with smoking, extreme inactivity also aggravated lung inflammation and emphysema, and accelerated body and muscle weight loss. This study shows that extreme inactivity, especially when imposed by absolute rest, accelerates lung damage and inflammation. When combined with smoking, extreme inactivity is deleterious for muscle bulk, bone and lungs. These data highlight that the consequences of physical inactivity during the course of COPD should not be neglected.

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Section: Discussionsupporting

confidence: 71%

Interaction between Physical Activity and Smoking on Lung, Muscle, and Bone in Mice

Cielen

Maes

Heulens

et al. 2016

Am J Respir Cell Mol Biol

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“…Exposure of soleus muscle to conditions of microgravity for long periods of time has been shown to result in significant weight loss and atrophic changes [2], [3], [4]. Moreover, a decrease in functional capacity has been reported for the whole muscle [5], [6] and for its isolated fibers [7]. The adverse changes developing in the soleus muscle are mainly due to disturbances in its electrical activity.…”

Section: Introductionmentioning

confidence: 99%

Possible Role of Non-Muscle Alpha-Actinins in Muscle Cell Mechanosensitivity

2014

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The main hypothesis suggested that changes in the external mechanical load would lead to different deformations of the submembranous cytoskeleton and, as a result, dissociation of different proteins from its structure (induced by increased/decreased mechanical stress). The study subjects were fibers of the soleus muscle and cardiomyocytes of Wistar rats. Changes in external mechanical conditions were reconstructed by means of antiorthostatic suspension of the animals by their tails for 6, 12, 18, 24 and 72 hours. Transversal stiffness was measured by atomic force microscopy imaging; beta-, gamma-actin, alpha-actinin 1 and alpha-actinin 4 levels in membranous and cytoplasmic fractions were quantified by Western blot analysis; expression rates of the corresponding genes were studied using RT-PCR. Results: In 6 hours, alpha-actinin 1 and alpha-actinin 4 levels decreased in the membranous fraction of proteins of cardiomyocytes and soleus muscle fibers, respectively, but increased in the cytoplasmic fraction of the abovementioned cells. After 6–12 hours of suspension, the expression rates of beta-, gamma-actin, alpha-actinin 1 and alpha-actinin 4 were elevated in the soleus muscle fibers, but the alpha-actinin 1 expression rate returned to the reference level in 72 hours. After 18–24 hours, the expression rates of beta-actin and alpha-actinin 4 increased in cardiomyocytes, while the alpha-actinin 1 expression rate decreased in soleus muscle fibers. After 12 hours, the beta- and gamma-actin content dropped in the membranous fraction and increased in the cytoplasmic protein fractions from both cardiomyocytes and soleus muscle fibers. The stiffness of both cell types decreased after the same period of time. Further, during the unloading period the concentration of nonmuscle actin and different isoforms of alpha-actinins increased in the membranous fraction from cardiomyocytes. At the same time, the concentration of the abovementioned proteins decreased in the soleus muscle fibers.

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“…To determine single-muscle fiber power generation, the isotonic load-clamping test was utilized (45). Briefly, when each fiber was fully activated in activating solution, the fiber was subjected to three successive submaximal isotonic load steps.…”

Section: Determination Of Powermentioning

confidence: 99%

“…Previously, the inactivity-induced decline in peak power, at the whole muscle level (soleus) (17,45) and at the single-fiber level (type I) (3,21), was investigated in rats with specific body masses (i.e., 250 -275 or 300 -350 g in Sprague-Dawley) or rats with specific ages (i.e., adult). Although our finding is consistent with previous data showing that 2 wk of inactivity reduced absolute peak power of type I fibers in the adult rats (3,21), our comprehensive evaluation shows a period of inactivity is detrimental to power generation, regardless of the age of the animal, young or old.…”

Section: Absolute Peak Powermentioning

confidence: 99%

Differential effects of mild therapeutic exercise during a period of inactivity on power generation in soleus type I single fibers with age

Kim

Thompson

2012

Journal of Applied Physiology

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Kim JH, Thompson LV. Differential effects of mild therapeutic exercise during a period of inactivity on power generation in soleus type I single fibers with age. J Appl Physiol 112: 1752-1761, 2012. First published March 15, 2012 doi:10.1152/japplphysiol.01077.2011.-The purpose of this study was to investigate the effects of mild therapeutic exercise (treadmill) in preventing the inactivity-induced alterations in contractile properties (e.g., power, force, and velocity) of type I soleus single fibers in three different age groups. Young adult (5-to 12-mo-old), middle-aged (24-to 31-mo-old), and old (32-to 40-mo-old) F344BNF1 rats were randomly assigned to three experimental groups: weightbearing control (CON), non-weight bearing (NWB), and NWB with exercise (NWBX). NWB rats were hindlimb suspended for 2 wk, representing inactivity. The NWBX rats were hindlimb suspended for 2 wk and received therapeutic exercise on a treadmill four times a day for 15 min each. Peak power and isometric maximal force were reduced following hindlimb suspension (HS) in all three age groups. HS decreased fiber diameter in young adult and old rats (Ϫ21 and Ϫ12%, respectively). Specific tension (isometric maximal force/cross-sectional area) was significantly reduced in both the middle-aged (Ϫ36%) and old (Ϫ23%) rats. The effects of the mild therapeutic exercise program on fiber diameter and contractile properties were age specific. Mild treadmill therapeutic exercise attenuated the HS-induced reduction in fiber diameter (ϩ17%, 93% level of CON group) and peak power (N·fiber length·s Ϫ1 ) (ϩ46%, 63% level of CON group) in young adult rats. In the middle-aged animals, this exercise protocol improved peak power (ϩ60%, 100% level of CON group) and normalized power (kN·m Ϫ2 ·fiber length·s Ϫ1 ) (ϩ45%, 108% level of CON group). Interestingly, treadmill exercise resulted in a further reduction in shortening velocity (Ϫ42%, 67% level of CON group) and specific tension (Ϫ29%, 55% level of CON group) in the old animals. These results suggest that mild treadmill exercise is beneficial in attenuating and preventing inactivity-induced decline in peak power of type I soleus single fibers in young adult and middle-aged animals, respectively. However, this exercise program does not prevent the HS-induced decline in muscle function in the old animals.

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Detrimental effects of reloading recovery on force, shortening velocity, and power of soleus muscles from hindlimb-unloaded rats

Cited by 31 publications

References 45 publications

Interaction between Physical Activity and Smoking on Lung, Muscle, and Bone in Mice

Interaction between Physical Activity and Smoking on Lung, Muscle, and Bone in Mice

Possible Role of Non-Muscle Alpha-Actinins in Muscle Cell Mechanosensitivity

Differential effects of mild therapeutic exercise during a period of inactivity on power generation in soleus type I single fibers with age

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