Plantaris Muscle (plantari + muscle)

Distribution by Scientific Domains


Selected Abstracts


Changes in skeletal muscle size, fibre-type composition and capillary supply after chronic venous occlusion in rats

ACTA PHYSIOLOGICA, Issue 4 2008
S. Kawada
Abstract Aim:, We have previously shown that surgical occlusion of some veins from skeletal muscle results in muscle hypertrophy without mechanical overloading in the rat. The present study investigated the changes in muscle-fibre composition and capillary supply in hypertrophied muscles after venous occlusion in the rat hindlimb. Methods:, Sixteen male Wistar rats were randomly assigned into two groups: (i) sham operated (sham-operated group; n = 7); (ii) venous occluded for 2 weeks (2-week-occluded group; n = 9). At the end of the experimental period, specimens of the plantaris muscle were dissected from the hindlimbs and subjected to biochemical and histochemical analyses. Results:, Two weeks after the occlusion, both the wet weight of plantaris muscle relative to body weight and absolute muscle weight showed significant increases in the 2-week-occluded group (,15%) when compared with those in the sham-operated group. The concentrations of muscle glycogen and lactate were higher in the 2-week-occluded group, whereas staining intensity of muscle lipid droplets was lower in the 2-week-occluded group than those in the sham-operated group. The percentage of type I muscle fibre decreased, whereas that of type IIb fibre increased in the 2-week-occluded group when compared with the sham-operated group. Although the expression of vascular endothelial growth factor-188 mRNA increased, the number of capillaries around the muscle fibres tended to decrease (P = 0.07). Conclusion:, Chronic venous occlusion causes skeletal muscle hypertrophy with fibre-type transition towards faster types and changes in contents of muscle metabolites. [source]


Detraining losses of skeletal muscle capillarization are associated with vascular endothelial growth factor protein expression in rats

EXPERIMENTAL PHYSIOLOGY, Issue 2 2010
Moh H. Malek
The purposes of this study were as follows: (1) to examine basal vascular endothelial growth factor (VEGF) protein concentrations following 10 weeks of endurance training and after 7 days of detraining; and (2) to examine the acute VEGF protein response to a single 1 h exercise work bout in trained and detrained animals in relationship to changes in capillary indices following training and detraining. Thirty-three Sprague,Dawley rats were randomized into the following six groups: (1) control,basal; (2) control,acute exercise; (3) trained,basal; (4) trained,acute exercise; (5) detrained,basal; and (6) detrained,acute exercise. Groups 3,6 performed endurance training on a rodent treadmill three times per week for 10 weeks. Following the training intervention, rats in groups 5 and 6 remained cage confined (i.e. detrained) for 7 days. As expected, training increased soleus and plantaris muscle capillarity and attenuated the VEGF response to acute exercise. Seven days of detraining, however, resulted in a regression of capillary contacts and individual capillary-to-fibre ratio in the plantaris and soleus muscles compared with the trained group (P < 0.05). Restoration of the VEGF protein response to acute exercise was evident in both muscles, but only statistically significant in the plantaris muscle (P < 0.05). This is the first study to demonstrate the temporal relationship between VEGF protein expression and skeletal muscle capillarity within the first week of detraining. The findings of the present investigation are consistent with the hypothesis that reduced capillarity impairs oxygen availability to the working muscles. The results indicated that training-induced angiogenic remodelling was reversible following 1 week of detraining and may be modulated by VEGF. [source]


Anatomical variations of the plantaris muscle and a potential role in patellofemoral pain syndrome

CLINICAL ANATOMY, Issue 2 2008
A. Jay Freeman
Abstract The plantaris muscle has been given little attention in the reviewed literature. It is most commonly mentioned only when absent from a specimen. This study aimed to document the anatomy of the plantaris muscle and to discuss the clinical significance of the observations. Cadaveric knees (n = 46) were dissected to identify the possible variations of the plantaris muscle. The muscle conformed with standard descriptions (n = 26; 56.52%), was present but varied from previous descriptions (n = 14; 30.44%), or was absent (n = 6; 13.04%). The variations consisted of distinct interdigitations with the lateral head of the gastrocnemius muscle (n = 9; 19.57%) and a strong fibrous extension of the plantaris muscle to the patella (n = 5; 10.87%). The presence of interdigitations strengthen the argument that the plantaris muscle supplement the activity of the lateral head of the gastrocnemius muscle whereas the patellar extension suggests an involvement with patellofemoral dynamics and may play a role in the various presentations of patellofemoral pain syndrome. Greater understanding of the relationship between these and other posterior knee structures will facilitate more precise interpretation and treatment of knee injuries. Clin. Anat. 21:178,181, 2008. © 2008 Wiley-Liss, Inc. [source]


Ageing influences myonuclear domain size differently in fast and slow skeletal muscle of rats

ACTA PHYSIOLOGICA, Issue 1 2009
N. E. Brooks
Abstract Aim:, In multinucleated skeletal muscle, a myonuclear domain is the region of cytoplasm governed by one nucleus, and myofibres are mosaics of overlapping myonuclear domains. Association of ageing and myonuclear domain is important in the understanding of sarcopenia and with prevention or combating age-related muscle declines. This study examined the effects of age, fibre type and muscle on nucleo-cytoplasmic (N/C) relationships as reflecting myonuclear domain size. Methods:, The N/C was compared in fibre types of soleus and plantaris muscles from young (n = 6) and ageing (n = 8) male Fisher 344 rats. Results:, There were no significant differences in fibre type composition or cross-sectional area of the soleus across ages. The old soleus had significantly more myonuclei, resulting in a significantly smaller myonuclear domain size. The plantaris muscle showed a higher percentage of slow fibres in old compared with young fibres. There were no differences in the number of myonuclei or in myonuclear domain size between young and older animals. Conclusion:, We found muscle-specific differences in the effects of ageing on myonuclear domain, possibly as a result of reduced efficiency of the myonuclei in the slow muscles. [source]


Exercise training in late middle-aged male Fischer 344 × Brown Norway F1-hybrid rats improves skeletal muscle aerobic function

EXPERIMENTAL PHYSIOLOGY, Issue 7 2008
Andrew C. Betik
The Fischer 344 × Brown Norway F1-hybrid (F344BN) rat has become an increasingly popular and useful strain for studying age-related declines in skeletal muscle function because this strain lives long enough to experience significant declines in muscle mass. Since exercise is often considered a mechanism to combat age-related declines in muscle function, determining the utility of this strain of rat for studying the effects of exercise on the ageing process is necessary. The purpose of this study was to evaluate the plasticity of skeletal muscle aerobic function in late middle-aged male rats following 7 weeks of treadmill exercise training. Training consisted of 60 min per day, 5 days per week with velocity gradually increasing over the training period according to the capabilities of individual rats. The final 3 weeks involved 2 min high-intensity intervals to increase the training stimulus. We used in situ skeletal muscle aerobic metabolic responses and in vitro assessment of muscle mitochondrial oxidative capacity to describe the adaptations of aerobic function from the training. Training increased running endurance from 11.3 ± 0.6 to 15.5 ± 0.8 min, an improvement of ,60%. Similarly, distal hindlimb muscles from trained rats exhibited a higher maximal oxygen consumption in situ (23.2 ± 1.3 versus 19.7 ± 0.8 ,mol min,1 for trained versus sedentary rats, respectively) and greater citrate synthase and complex IV enzyme activities in gastrocnemius (29 and 19%, respectively) and plantaris muscles (24 and 28%, respectively) compared with age-matched sedentary control animals. Our results demonstrate that skeletal muscles from late middle-aged rats adapt to treadmill exercise by improving skeletal muscle aerobic function and mitochondrial enzyme activities. This rat strain seems suitable for further investigations using exercise as an intervention to combat ageing-related declines of skeletal muscle aerobic function. [source]