To define more clearly and to treat those disorders affecting the neuromuscular apparatus which present primarily with episodic weakness or paralysis or are characterized by a significant amount of myotonia. Attention is directed toward those conditions in which evidence suggests that the main site of intermittent dysfunction is somewhere within the following portions of the muscle fiber: plasmalemma, T-system, sarcoplasmic reticulum, myofibrillar complex (i.e., the total excitation-contraction coupling mechanism). With respect to periodic paralysis syndromes, studies are done with agents which are transiently either therapeutic or provocative, with a view to obtaining more information regarding abnormalities of pertinent metabolic pathways and methods of treatment. The various myotonia disorders are studied with respect to more clearly defining the molecular abnormalities, seeking the underlying pathogenesis and treatment thereof, and finding better ways of symptomatically treating their myotonia. Induced animal-models of myotonia are also used for these purposes. BIBLIOGRAPHIC REFERENCES: Griggs, R.C., Moxley, R.T., Riggs, J.E. and Engel, W.K.: Effect of acetazolamide on myotonia. Ann. Neurol 1: 507, 1977. Reddy, N.B., Oliver, K.L. and Engel, W.K.: Alterations in the sarcolemmal (SL) adenylate cyclase activity (AC-a) in myotonia. Neurology, 27: 378, 1977.