[Change in the ultrastructure of the muscles in thyrotoxic periodic paralysis].

The article presents data on the clinico-morphological study of three patients suffering from thyrotoxicosis with attacks of periodic paralysis. The muscles obtained by biopsy in two patients at the moment of attack and in one patient--in the absence of attack were investigated by the electron microscopy method. The data obtained make it possible to assume that in the thyrotoxic periodic paralysis the action of the thyroid hormones causes not only impairment of the mineral metabolism, but brings about changes in the structure of the membranes of the sarcolemma and T-system, which leads to disturbances of conductance of action potential into the fibre. These changes affect the function of the end cisterns and lead to distorsion of the processes of conjugation of excitation-contraction with resulting development of paresis and paralysis of muscles. Moreover, during the attack there take place secondary disturbances of carbohydrate metabolism, which aggravates the pathological process.