Fig. 6.

Agonist-induced Ca²⁺ influx in single pituitary cells and LβT2 gonadotrophs. Top, Characterization of Ca²⁺ influx pathway in pituitary gonadotrophs. Effects of ACh (A) and nicotine (B) on [Ca²⁺]_i in gonadotrophs bathed in Ca²⁺-containing medium. Nicotine was ineffective in cells bathed in medium containing cytisine, a specific blocker of β2-subunit-containing nAChR (B). In most of the cells, ACh induced additional rise in [Ca²⁺]_i in the presence of cytisine (C) or nicotine (D). GnRH was added at the end of recording to identify gonadotrophs. Bottom, Characterization of Ca²⁺ influx pathway in LβT2 cells. Nicotine induced a rise in [Ca²⁺]_i in cells with blocked M3-mAChR by DAU 5884 (E). Stimulatory effects of nicotine on Ca²⁺ influx was abolished in cells bathed with 4 μm cytisine (F). In a fraction of cells, ACh induced additional rise in [Ca²⁺]_i in the presence of cytisine (G) or nicotine (H).