Fig. 2.

Nicotine and mecamylamine (Mec) confirm nAChR effect. Ai: ACh/At-induced inward current [black trace, control (Cont) conditions] is abolished upon bath application of 5 μM Mec (red trace). Aii: the same cell as in Ai is depolarized upon ACh/At application (upper trace). The depolarization is blocked during bath application of 5 μM Mec (bottom trace). Aiii: effect of Mec on nAChR currents (Cont, ACh/At alone; +Mec, ACh/AT-induced currents in the presence of 5 μM Mec; Wash, ACh/At response after washout of the antagonist). Mec causes a reversible block of 1 mM ACh/At-induced currents (***P < 0.001). Cont: n = 5; +Mec: n = 5; Wash: n = 4. Bi and Bii: 5 μM Mec reversibly blocks the increase in sIPSC frequency in ET cells. Frequency plots from two cells are shown. Arrows denote the start of 1-s, 1 mM ACh/At applications. Black: ACh/At; red: ACh/At responses in the presence of 5 μM Mec; green: ACh/At responses after washout of the antagonist. In Bi, Mec reduced ACh/At responses by 80% of the Cont responses, which recovered to 65% of Cont values after a 15-min wash. In Bii, Mec blocked responses by 97.3%, and the response recovered to 77% of Cont values. Biii: Mec reversibly abolishes the ACh/At-induced increase in sIPSC frequency (***P < 0.001, *P < 0.05). Basal: sIPSC frequency under basal conditions; n = 10; ACh/At: n = 10; +Mec: n = 10; Wash: n = 4. Events were calculated over 10 s from the time of agonist application. Ci: a 30-s application of 5 μM nicotine (horizontal bar) results in the depolarization and increased firing of an ET cell. Cii: 5 μM nicotine application increases the mean firing rates of individual ET cells. Mean increase in frequency is represented by the green line (n = 10, *P < 0.05). Di: 5 μM nicotine application increases the average sIPSC frequency in an ET cell. Top trace, basal; bottom trace, response to nicotine. Dii: nicotine application resulted in a 14.6 ± 3.5-fold increase in sIPSC frequency (n = 9, **P < 0.01).