Fig. 4.

Chronic nicotine exposure mimics αBTX in inhibiting PHA 568487-induced α7 nAChR activation-dependent increases of [Ca²⁺]_i and [cAMP]_i in human airway epithelial cells. Air–liquid interface HAEC cultures were apically incubated for 3 h with αBTX (0–10 µM) or overnight with nicotine (0–10 µM). Three minutes after the addition of PHA 568487 (10 µM), [Ca²⁺]_i (A) and [cAMP]_i (B) were measured (Fig. 3 A and B). Results correspond to five HAEC cultures derived from different patients and were compared with the corresponding control exposed to only 10 µM PHA 568487.