In the Etruscan shrew, the isometric twitch contraction times of extensor digitorum longus (EDL) and soleus muscles are shorter than in any other mammal, allowing these muscles to contract at outstandingly high contraction frequencies. This species has the highest mass-specific metabolic rate of all mammals and requires fast skeletal muscles not only for locomotion but also for effective heat p...

We used intact fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles from rats and mice to test the hypothesis that exogenous application of an oxidant would increase maximum isometric force production (P(o)) of slow-twitch muscles to a greater extent than fast-twitch skeletal muscles. Exposure to an oxidant, hydrogen peroxide (H(2)O(2); 100 microM to 5 mM, 30 min), affecte...

Oxidative capacity of muscles correlates with capillary density and with microcirculation, which in turn depend on various regulatory factors, including NO generated by endothelial nitric oxide synthase (eNOS). To determine the role of eNOS in patterns of regulation of energy metabolism in various muscles, we studied mitochondrial respiration in situ in saponin-permeabilized fibres as well as t...

January/February 2005 • Vol 95 • No 1 • Journal of the American Podiatric Medical Association Equinus deformity is defined as a limitation of dorsiflexion motion of the ankle joint. Although many authors have attempted to specify the necessary degrees of ankle dorsiflexion, normative values have been limited.1, 2 Biomechanically, the maximum amount of dorsiflexion in the stance phase of normal ...

Angiotensin-converting enzymes 1 (ACE1) and 2 (ACE2) are key enzymes of the renin-angiotensin system, which act antagonistically to regulate the levels of angiotensin II (Ang II) and Ang-(1-7). Considerable data show that ACE1 acts on normal skeletal muscle functions and architecture. However, little is known about ACE1 levels in muscles with different fiber compositions. Furthermore, ACE2 leve...

After cessation of hindlimb immobilization, which resulted in a 27-37% loss in soleus mass, the atrophied soleus muscle of young but not old rats regrows to its mass before treatment. We hypothesized that during remobilization the mRNA levels of growth potentiating factor(s) would be present in the soleus muscle of young (3- to 4-mo-old) but absent in old (30- to 31-mo-old) Fischer 344 x Brown ...

BACKGROUND Fibroblast growth factor-2 (FGF-2) protein level has been shown to be elevated in aged mice muscle compared to adult mice. It activates the satellite cell quiescence, which leads to satellite cell depletion and may accelerate aging process. The purpose of this study was to see the effect of resistance exercise on skeletal muscle FGF-2 protein level in aged mice. METHODS This study ...

This study was designed to test the hypothesis that myosin heavy (MHC) and light chain (MLC) plasticity resulting from hindlimb suspension (HS) is an age-dependent process. By using an electrophoretic technique, the distribution of MHC and MLC isoforms was quantitatively evaluated in the soleus muscles from 3- or 12-wk-old rats after 1-3 wk of HS treatment was maintained. In normal 12- and 15-w...

Several aspects of lipid metabolism in the soleus and diaphragm muscles of streptozotocin-diabetic and control rats were investigated. The triglyceride content of both muscles was elevated in the diabetic state and the presence of increased intracellular lipid was confirmed by electron microscopy. In vitro glucose and palmitate oxidation studies showed that both types of muscle from the diabeti...