Effects of acetylcholine and other medullary secretagogues and antagonists on the membrane potential of adrenal chromaffin cells: an analysis employing techniques of tissue culture.

1. A method has been devised for isolating adrenal chromaffin cells (from gerbils) and maintaining them in vitro. Transmembrane potentials of these cells were recorded with intracellular micro-electrodes.2. Acetylcholine depolarized the chromaffin cells and so did various other substances known to evoke catecholamine secretion: nicotine, pilocarpine, histamine, 5-hydroxytryptamine, angiotensin, and bradykinin.3. The depolarizing effect of acetylcholine was partially antagonized by hexamethonium and was blocked completely by hexamethonium in combination with atropine.4. Hexamethonium alone completely blocked the response to nicotine; and atropine alone abolished the response to pilocarpine. Thus both nicotinic and muscarinic receptors are present in gerbil chromaffin cells.5. The experiments demonstrate that the various secretagogues and antagonists tested act on the plasma membrane of the chromaffin cell and raise the question whether depolarization may be an important event in stimulus-secretion coupling.