Effects of compensatory hypertrophy on dystrophic (Bio 14.6) hamster muscle : changes in collagen and myofibrillar protein content

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Authors
Fair, Jeanette L.
Advisor
Craig, Bruce W.
Issue Date
1987
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Degree
Thesis (M.A.)
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Abstract

Compensatory hypertrophy was induced on the plantaris (PL) and soleus (SOL) muscles of five week old normal and dystrophic (strain 14.6) hamsters. This was done to indicate whether submaximal exercise would be beneficial in reducing the progression of the muscular dystrophy (i.e., by causing muscle hypertrophy, reducing the total collagen content, and increasing the total protein content of the diseased muscle to approximate that of normal tissue).The hamsters were divided into four groups: 1) dystrophic overload (DO), 2) dystrophic control (DC), 3) normal overload (NO), and 4) normal control (NC). Eight weeks of overload of the PL and SOL muscles was induced by surgical ablation of the synergistic gastrocnemius muscle. Muscle wet weight data indicated significant muscle hypertrophy of 125% and 92% in the NO and DO PL respectively, and 60% in the NO SOL. Dry muscle weight data was comparable to the above results. There was no significant difference in the muscle collagen content between the NC and DC groups. Collagen content increased significantly in the NO and DO PL by 81% and 41% respectively, and in the NO and DO SOL by 127% and 57% respectively. The DC muscle was significantly lower in protein content than the NC muscle (180.2mg/g and 210.1 mg/g respectively) when expressed per g of wet muscle weight. This significance disappears when expressed per g dry muscle weight. The overload caused a significant decrease in the protein content of only the NO group when expressed by both wet and dry tissue weights (171.7mg/g and 678.3mg/g rrespectively). The hydration of the DC group was significantly higher than the NC group. The overload resulted in a significant increase in the water content of only the NO muscle.The results of this study indicate that dystrophic muscle will hypertrophy as indicated by muscle weight data. However, the significance of the data from the total collagen and total protein determination of the overload groups was inconclusive due to the formation of scar tissue. This scar tissue resulted in high collagen content. The high glycine content in this collagen in turn resulted in low protein values.

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