Little is known about the mechanisms responsible for the adaptation and changes in the capillary network of hindlimb unweighting (HU)-induced atrophied skeletal muscle, especially the coupling between functional and structural alterations of intercapillary anastomoses and tortuosity of capillaries. We hypothesized that muscle atrophy by HU leads to the apoptotic regression of the capillaries an...

Although estrogen loss can alter skeletal muscle recovery from disuse, the specific components of muscle regrowth that are estrogen sensitive have not been described. The primary purpose of this study was to determine the components of skeletal muscle mass recovery that are biological targets of estrogen. Intact, ovariectomized (OVX), and ovariectomized with 17beta-estradiol replacement (OVX+E2...

An accessory soleus muscle is a rare anatomical variant. Clinical awareness of this entity and the appropriate use of magnetic resonance imaging (MRI) can yield a definitive diagnosis in those patients with symptomatic accessory muscles. A case is presented in which the unique sensitivity of MRI in the evaluation of exertional muscle injuries proved useful in the detection of an accessory soleu...

Andrade SF, Skiba GH, Krueger E, Rodacki, AF. Effects of Electrostimulation with Blood Flow Restriction on Muscle Thickness and Strength of the Soleus. JEPonline 2016;19(3):59-69. The purpose of this study was to investigate the effects of low-intensity neuromuscular electrical stimulation (NMES) combined with blood flow restriction (BFR) to increase soleus muscle size and strength. Seven untra...

Post-tetanic potentiation of muscle contraction strength (PTP) occurs in cat soleus and gastrocnemius muscles. However, the mechanisms of potentiation are different in these two muscles. Soleus PTP is predominantly a neural event. The application of a high frequency stimulus to the soleus nerve regularly causes each subsequent response to a single stimulus to become repetitive. This post-tetani...

Muscle mass is decreased with advancing age, likely due to altered regulation of muscle fiber size. This study was designed to investigate cellular mechanisms contributing to this process. Analysis of male Fischer 344 X Brown Norway rats at 6, 20, and 32 mo of age demonstrated that, even though significant atrophy had occurred in soleus muscle by old age, myofiber nuclear number did not change,...

Persons with Down syndrome (DS) exhibit low muscle strength that significantly impairs their physical functioning. The Ts65Dn mouse model of DS also exhibits muscle weakness in vivo and may be a useful model to examine DS-associated muscle dysfunction. Therefore, the purpose of this experiment was to directly assess skeletal muscle function in the Ts65Dn mouse and to reveal potential mechanisms...

Djungarian hamsters (Phodopus sungorus) undergo bouts of daily torpor in response to reduced photoperiod. Metabolic rate, body temperature and energy cost are reduced during torpor. The present study exposed Djungarian hamsters to two different photoperiod regimes at a room temperature of 19-21°C: long photoperiod (control, 16 h:8 h light:dark, N=8) and short photoperiod (torpor, 8 h:16 h light...

Our aim was to analyze the role of phosphatidylinositol 3-kinase (PI3K)-AKT and MAPK signaling pathways in the regulation of muscle mass and slow-to-fast phenotype transition during hindlimb unloading (HU). For that purpose, we studied, in rat slow soleus and fast extensor digitorum longus muscles, the time course of anabolic PI3K-AKT-mammalian target of rapamycin, catabolic PI3K-AKT-forkhead b...