Movement of Potassium Into Skeletal Muscle During Spontaneous Attack in Family Periodic Paralysis 1

It has been appreciated since the classical stud- ies of Biemond and Daniels (1) and Aitken, Allott, Castleden, and Walker (2) that the concentration of potassium in serum falls during attacks in pa- tients with typical family periodic paralysis.Allott and McArdle (3), Pudenz, McIntosh, and McEachern (4) and Ferrebee, Atchley, and Loeb (5) showed that the quantity of potassium ex- creted in urine was reduced during attacks of paralysis.These observations implied that during attacks potassium shifted from extracellular to some intracellular space.Metabolic balance stud- ies by Danowski, Elkinton, Burrows, and Winkler (6) confirmed this hypothesis.The question of which intracellular space accepted the potassium that shifted during attacks remained unanswered.Recently it has been reported from this labora- tory that there is a diurnal variation in normal man in exchange of potassium between skeletal muscle and extracellular water (7).During the hours between 10 P.M. and 12 noon, that is, 4 to 18 hours after the last meal, with the subject at rest, potassium moves from muscle to blood, the rate declining to a minimum or even reversing slightly (potassium moves from blood to muscle) between the hours of midnight and 7 A. M., and then rising again to a peak between 10 A.M. and noon.It is characteristic of family periodic paralysis that most attacks begin during the middle of the night (8).This suggested that in patients with this disease there may be an exaggeration of the diurnal variation in potassium movement, and that movement of potassium from extracellular fluid into skeletal muscle during the night might be re- ' This work was performed under a contract between the Office of Naval Research, Department of the Navy, and The Johns Hopkins University (NR 113-241) and was further supported by grants-in-aid from the National Institutes of Health, Department of Health, Education, and Welfare (A-750) and the Muscular Dystrophy As- sociations of America, Inc.sponsible for the attacks.It is the purpose of this report to present data indicating that this is the case.