FACTORS AFFECTING THE LOSS OF POTASSIUM FROM STIMULATED MUSCLES

Abstract

The loss of K resulting from stimulation of the muscles of anesthetized cats is somewhat less when the tendon is cut than when the muscle pulls against an isometric lever. Curtailment of the circulation through a stimulated muscle, thus partially asphyxiating it, decreases the loss of K but increases the gain of water. The loss of K is therefore not in proportion to the amt. of lactic acid formed. The gain of water is less after long periods of stimulation (4.5 hours) than after short periods of 30 minutes. The loss of K is increased if the no. of tetani per sec. is doubled, but it is diminished if the muscle is tetanized continuously. The loss of K, gain of H2O, and gain of chloride are all at a maximum at a frequency of stimulation of about 8 per sec. (incomplete tetanus). A complete tetanus has less effect and an inhibited tetanus at still higher frequency still less. The loss of K is proportional to the magnitude of the contraction but is particularly favored by rhythmical contractions.