UPTAKE OF [H-3]-LABELED NICOTINE AND [H-3]-LABELED NORADRENALINE BY CULTURED CHROMAFFIN CELLS

Three day‐old cultured bovine adrenal chromaffin cells incubated at room temperature with Krebs‐HEPES solution containing different concentrations of [3H]‐nicotine, took up and retained increasing amounts of the drug by a mechanism that did not saturate. Concentrations of cold nicotine as high as 100 μm did not alter the amount of [3H]‐nicotine retained by cells. Imipramine, cocaine, tetracaine or mecamylamine, at concentrations (10 μm) that blocked the catecholamine secretory effects of nicotine completely, did not modify the uptake of [3H]‐nicotine. Both imipramine and cocaine drastically inhibited [3H]‐noradrenaline uptake by cells in a concentration‐dependent manner (IC50s of 0.08 and 1 μm, respectively). These data indicate that the secretory effects of nicotine are not coupled to its previous uptake into cells, and are evidence in favour of a site of action for nicotine located in or at the surface of the chromaffin cell membrane. 1984 British Pharmacological Society