Effect of acetylcholine on the electrical activity of somatic nerves of the lobster.

The effects of acetylcholine (ACh) on axons of the walking leg of lobster have been investigated. In 10(-2)M concentration the ester lowers the resting potential by approximately 7 mv within 10 minutes. Simultaneously, the spike height is decreased. Complete but reversible block ensues in 10 to 15 minutes. At lower concentrations essentially similar but smaller effects are observed. Choline chloride and sodium acetate, at concentrations of 10(-2)M, are without any effect. In conjunction with the evidence accumulated for the essential role of acteylcholine in the control of ion movements, the demonstration of the ability of acetylcholine to reversibly depolarize axons of somatic nerve fibers appears pertinent.