The effect of Rb+, Cs+, and T1+ on the gramicidin A-induced conductance changes of the skeletal muscle cell membrane.

Abstract

The channel-forming antibiotic gramicidin A increases the K+ conductance of frog skeletal muscle fibres in isotonic K2SO4 solution. The conductance of the gramicidin channel is not affected by Rb+ or Cs+, but is reduced by T1+. In contrast, the conductance of the normal K+ channel is decreased by Rb+ and Cs+ but is nearly unaffected by 5 and 10 mM T1+. The results suggest differences in the cation permeation through the gramicidin and the K+ channel of the muscle cell membrane.