Effect of denervation on the permeability of acetylcholine-activated channels to organic cations.

Experiments were perfomed on chronically denervated frog sartorius muscles to determine the permeability of the acetylcholine-activated channels to organic cations. The membrane voltage response to bath-applied acetylcholine was measured with the moving electrode when the muscles were bathed in normal Ringer and in Ringer in which all of the Na+ had been replaced with an organic cation. The magnitude of the maximum voltage response was used to estimate the permeability of the channel to the organic cation. These results were compared with those which have been reported for innervated frog sartorius muscles (Maeno, Edwards, and Anraku, 1977). It is concluded that the permeability to a wide range of organic cations is virtually identical for the extrajunctional channels which develop following denervation and the channels with are localized at the junctional region of innervated muscles.