[Effect of thyroxine on skeletal muscles in hereditary myodystrophia]

The influence of 3-week L-thyroxin administration on contractility and histochemical composition of skeletal muscles was studied in 129Rj mice of normal and dystrophic genotypes. The rise in speed characteristics of isometric contraction and percentage of type II "fast" fibers was established in both types of animals. Contractile properties in dystrophic animals, receiving L-thyroxin, showed a tendency towards normalization and were comparable to those of normal animals.