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. 2022 Aug 9;67(5):550–561. doi: 10.1165/rcmb.2021-0320OC

Figure 1.

Figure 1.

 β-arrestin recruitment and calcium mobilization by muscarinic ligands. (A) Methacholine (MCh) (0.1, 1, 10, or 100 μM) and (B) PD 102807 (1, 10, or 100 μM) induce M3-mediated β-arrestin recruitment as assessed by bioluminescence resonance energy transfer (BRET) signal in HEK293 cells. (C) PD 102807 is a competitive antagonist of the M3 mAChR. Calcium mobilization in airway smooth muscle (ASM) cells by different concentrations of MCh in the presence or absence of PD 102807 (1, 10, or 100 μM; 15 min pretreatment) using Flexstation. (D) Maximal increase in β-arrestin recruitment BRET signal by mAChR ligands (100 μM) in HEK293 cells. (E) Net maximal calcium mobilization by mAChR ligands (100 μM) in human ASM cells stably expressing telomerase reverse transcriptase (hTERT) ASM cells. (F) Relationship between net maximal calcium mobilization and β-arrestin recruitment for each of the characterized mAChR ligands. Data are means ± SEM from two to four experiments. CCh = carbachol; MCh = methacholine; Musc = muscarine; OXO = oxotremorine sesquifumarate; OXO-M = oxotremorine-M; Pilo = pilocarpine; PD = PD 102807; Veh = vehicle.