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Volume :29 Issue : 1 2002
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Effect of immobilization and under-load on skeletal muscle in the Hindlimb of the Jerboa
Auther : F. A. ARYAN AND M. A. ALNAQEEB*
Department of Biological Sciences, Zoology Program, Kuwait University, P.O. Box
5969. Safat 13060, Kuwait, e-mail: anaqeeb@kuc01 .kuniv.edu.kw
ABSTRACT
The jerboa (Jaciilus jaculus) was used as a model of the bipedal mode of locomotion to study the effects of two immobilization positions on the extensor digitorum longus (EDL) and soleus muscles of the hindlimb. Cast immobilization was used to simulate the effect of disuse and hypo-activity on muscle properties. Fiber type, number and fiber diameter were examined to determine the effects of immobilization on the muscles. Immobilizing the EDL muscle in both stretched and relaxed positions caused atrophy and muscle wasting by reducing muscle fiber diameters. On the other hand, no significant changes in muscle fiber number were noted. The stretched soleus muscle, on the other hand, showed a significant increase in muscle fiber diameter, combined with a change from type I to type II fibers; furthermore, a significant decrease in the total fiber number was also noted. The relaxed soleus however, showed a significant reduction in muscle fiber diameter and number with no change in fiber type.
Keywords: Extensor digitorum longus; fiber size; fiber types; fiber number; immobilization; Juculus jaculus; soleus.