Electrical phenomena associated with the activity of the membrane-bound acetylcholinesterase.

Treatment of isolated electroplax with physiological solutions supplemented with either 1 molar sodium chloride, 2 molar urea, or 2 molar sucrose renders the cell insensitive to carbamylcholine, phenyltrimethylammonium, or decamethonium even at high concentrations. The treated cells have a residual resting potential of -20 +/- 10 millivolts (negative inside) and are depolarized by acetylcholine at concentrations larger than 10(-3) mole per liter. This response is not affected by d-tubocurarine but is blocked by physostigmine, diisopropylphosphorofluoridate, or strong buffers and thus depends on the catalytic activity of the membrane-bound acetylcholinesterase.