Muscle membrane potentials in episodic adynamia

Abstract

1. 1. In vivo measurements of membrane potentials of human muscles (M. vastus med,; nerve block anaesthesia) have been performed in a healthy young man, a patient with periodic paralysis and a patient with episodic Adynamia (e.A.) Control measurements were performed in rats. 2. 2. The resting potentials of striated muscles of rats under general anaesthesia were − 79.9 ± 73.3 mV. In the healthy man (without general anaesthesia) the mean value was −87.4 ± 8.9 mV and in the patient with periodic paralysis it was −85.6 ± 6.1 mV in a free interval. During the attempt to provoke a paralytic attack in this patient the average dropped to −77.1 ± 8.2 mV, whereas the serum K + fell from 4.25 to 3.17 mequiv./1. The questionable significance of this slight drop of membrane potential is discussed. 3. 3. In the patient with e.A. the resting potential, even in the free interval, (serum K + 3.75 mequiv./l) was only −68.5 ± 5.9 mV. During an induced attack, with a rise in serum potassium to 6.9 mequiv./l, the average value dropped to −46.3 ± 6.6 mV and during a spontaneous attack, with a serum potassium of 5.24 mequiv./l, the mean value was −51.5 ± 6.3 mV. 4. 4. The significance of the results is discussed. The pathogenetic mechanism of e.A. can be explained by a disturbance of sodium permeability of muscle membranes.