Résumé :
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CHF147 hamster strain is an animal model of delta-sarcoglycan deficiency. Skeletal muscular dystrophy features observed in this model are very similar to those described in humans with more severe disease in proximal than distal muscles. Muscle activation in this limb girdle muscular dystrophy has not yet been studied. Our goal was to develop a standardized protocol for electromyography (EMG) study during either voluntary or electrically elicited contractions. Prior to surgery hamsters were trained to run at different speeds on a motor-driven treadmill. Tibialis anterior (TA) and vastus lateralis (VL) were instrumented in CHF147 and control animals during global anesthesia. In each muscle, electrodes were made up of two teflon insulated multistranded stainless wires (diameter = 110 µm). Recording surfaces were made by removing 1 mm of insulation and the distance between bared regions let to 2-2.5 mm centre-to-centre. The first recordings started at day 6 after surgery. Two kinds of measurements were performed. First, global EMG activity of TA and VL for each animal was recorded during 10-seconds runs at increasing treadmill velocities (from 15 to 35 cm.s-1). Secondly, electrical stimulation on anesthetized animals was performed in order to analyze muscle response during recruitment and fatigue. The methodology used in the present work generally yields EMG signals of good quality either during voluntary or during electrically elicited contractions. Intramuscular wires do not influence leg movements in hamsters. Various results in both contraction modes can be depicted. For example, during repeated stimulation at 20 Hz, compound muscle action potential amplitude decreased while its duration increased associated to spectral compression. The rate of change of such parameters can be used to assess muscle fatigability. This standardized procedure associated to reliable electrophysiological parameters may be useful for the follow-up of animals during the natural progression of the disease or during therapeutic trials.
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