Experimental thyrotoxic myopathy: radioautography of protein synthesis in skeletal muscle and motor neurons of spinal cord.

The total protein synthesis was studied in skeletal muscle and spinal motor neurons in experimental thyrotoxic myopathy (TM) mice by using radioautography with 3H-methionine. A significant increase of mean specific radioactivity was found in motor neurons of mice with TM. No statistical differences were established in the level of 3H-methionine inclusions into muscle fibre proteins of experimental and control animals. Thus, the total protein synthesis in motor neurons is significantly increased with TM, while there is no change in the skeletal muscle. Our data suggest that muscular weakness in TM is not the consequence of protein metabolism disorders in skeletal muscle fibres.