Extracellular 2‐chloroadenosine and ATP stimulate volume‐sensitive Cl− current and calcium mobilization in human tracheal 9HTEo− cells

Abstract

The perforated-patch whole-cell technique was used to record membrane currents in epithelial cells (9HTEo−) obtained from the human tracheal epithelium. Extracellular application of 2-chloroadenosine and ATP (0.01–100 μM) caused activation of Cl⁻ currents similar to those regulated by cell volume in airway and intestinal cells. This response was inhibited by increasing extracellular osmolality, by omission of extracellular Ca²⁺ or by the addition of the A₂ adenosine receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX). Fluorimetric measurements with fura-2 reveal that 2-chloroadenosine and ATP elicited both a Ca²⁺ influx through the plasma membrane and a release from intracellular stores.