(A) Nicotine, varenicline and lobeline chemical structures. (B) Varenicline and lobeline reduced nicotine upregulation of α4β2Rs for live cells, but not membranes. 125I-epibatidine binding performed …
(A) Dose dependence of varenicline upregulation. α4β2R-expressing cells were treated with increasing concentration of varenicline for 17 hr. Cells were washed with PBS prior to 125I-epibatidine …
(A) 125I-epibatidine binding on α4β2R-expressing HEK cells exposed to varenicline or lobeline 17 hr at 30 μM and then incubated twice (5 min each) with Bafilomycin A (50 nM), an inhibitor of …
(A) Schematic of the experimental details. (National Center for Chronic Disease Prevention and Health Promotion (US) Office on Smoking and Health, 2014). HEK cells stably expressing α4β2Rs were …
(A) In this and other recordings, a 17–20 hr treatment with nicotine (Nic, 10 μM) induced a robust, ~5 fold, increase in peak current amplitudes evoked by 1 mM ACh from α4β2R-expressing HEK cells. …
(A) DHβE, mecamylamine and epibatidine chemical structures. (B) NH4Cl treatment does not alter DHβE (DH) upregulation. 125I-epibatidine binding performed on live α4β2R-expressing cells without …
(A) Dose dependence of epibatidine upregulation. α4β2R-expressing cells were treated with increasing concentration of epibatidine for 17 hr. Cells were washed with PBS prior to 125I-epibatidine …
(A) The biphasic dissociation of 125I-epibatidine from α4β2R HEK cells measured at 37°C. Bound 125I-epibatidine is normalized to % bound at time 0. The line through the data represents a …
Live cells were bound with 0.1 nM 125I-epibatidine at room temperature for the indicated times. The line through the points represents a least-squares fit to the normalized 125I-epibatidine uptake …
(A) Imaging α4β2R-containing acidic vesicles and the effect of nicotine exposure. α4SEP was transfected into the α4β2R-expressing HEK cells. Image (100 x) of 3 merged slices near the cell surface …
(A) HEK cells are displayed 36 hr post transfection. Transfected α4SEP subunits (green) and DsRed ER (red) are imaged in untreated (top panel) or nicotine treated (10 μM for 17 hr; bottom panel) …
pKas and Kis for the studied weak base α4β2R ligands
Weak base | pKa (Basic) | Ki | Trapping |
---|---|---|---|
Varenicline (partial agonist) | 9.2 (Unal et al., 2012) | 0.4 nM (Rollema et al., 2010) | Yes |
Lobeline (partial agonist) | 8.8 (Drugbank, 2016) | four nM (Damaj et al., 1997) | Yes |
Epibatidine (agonist) | 9.5 (ChEMBL, 2017) | 0.01–0.05 nM (Whiteaker et al., 1998; Badio et al., 1994) | Yes |
Nicotine (agonist) | 8.0 (Barlow and Hamilton, 1962) | eight nM (Whiteaker et al., 1998) | No |
DHβE (competitive antagonist) | 7.3 (ChEMBL, 2017) | 0.3 μM (Whiteaker et al., 1998) | No |
Mecamylamine (noncompetitive antagonist) | 11.2 (Remington and Beringer, 2006; Nangia et al., 1996) | >1 mM (Whiteaker et al., 1998) | No |