Nitrate ions: Potentiation of increased permeability to sugar associated with muscle contraction.

Nitrate ions potentiate twitch tension and enhance the increase in permeability to sugar which occurs in electrically stimulated frog sartorius muscles. However, the potentiating effect of nitrate ions on permeability is not dependent upon an increase in twitch tension. The possible relation of changes in permeability to alterations of the concentration of calcium ions in the cell is discussed.