CHANGES IN PROTEIN CONTENT AND IN SOME PHYSICOCHEMICAL PROPERTIES OF THE PROTEIN DURING MUSCULAR ATROPHIES OF VARIOUS TYPES

Abstract

The total protein concn. in gas-trocnemii of rabbits diminishes by about 14% during atrophy due to denervation or due to tenotomy of 22-30 days duration. In atrophy due to cast in extended limb position, the wt. loss is nearly as large as in the 2 other atrophies, but the loss in total protein is only about 1/3 of the loss in the other atrophies. Collagen concn. increases in all 3 types of atrophy about reciprocally with the wt. loss, but the total amt. of collagen present in the whole muscle diminishes somewhat. Non-collagenous protein content is decreased by 13, 25 and 29% for immobilization, tenotomy, and denervation. The amt. of precipitable myosin is diminished 11% for immobilization, but 69 and 78% for tenotomy and denervation. This large decrease in myosin is due to the fact that in comparison with normal muscle a much smaller proportion of the protein can be extracted, and that only a smaller fraction of the latter can be precipitated as myosin. The hydrophylic power of the muscle mash is increased about 35% for immobilization and denervation, but decreased by about 13% for tenotomy. The neutralization power of the muscle extract is not altered by immobilization, but 22% and 72% increased by denervation and tenotomy.