Muscarinic acetylcholine receptor subtype 3 (M3 receptor) is a G Protein-Coupled Receptor (GPCR) that mediates many important physiological functions. Currently, most M3 receptor drugs also have high affinity for other subtypes of muscarinic acetylcholine receptors (mAChRs) and produce the risk of side effects. Therefore, in order to find M3 receptor drugs with high specificity, high activity and low side effects, we established a cell model and method for efficient and sensitive screening of M3 receptor based on calcium-activated chloride channels (CaCCs), and this method is also suitable for the screening of other GPCR drugs. This screening model consists of Fischer rat thyroid follicular epithelial (FRT) cells that endogenously express M3 receptors, CaCCs, and the indicator YFP-H148Q/I152L. We verified that the model can sensitively detect changes in intracellular Ca²⁺ concentration using fluorescence quenching kinetics experiments, confirmed the screening function of the model by applying available M3 receptor drugs, and also evaluated the good performance of the model in high-throughput screening.

毒蕈碱性乙酰胆碱受体亚型 3（M3 受体）是一种 G 蛋白偶联受体 (GPCR)，可介导许多重要的生理功能。目前，大多数M3受体药物还对毒蕈碱型乙酰胆碱受体（mAChRs）的其他亚型具有高亲和力，并有产生副作用的风险。因此，为寻找高特异性、高活性、低副作用的M3受体药物，我们建立了基于钙激活氯离子通道（CaCCs）的高效灵敏筛选M3受体的细胞模型和方法，该方法是也适用于其他GPCR药物的筛选。该筛选模型由内源性表达 M3 受体、CaCC 和指示剂 YFP-H148Q/I152L 的 Fischer 大鼠甲状腺滤泡上皮 (FRT) 细胞组成。²⁺浓度使用荧光猝灭动力学实验，通过应用现有的M3受体药物证实了模型的筛选功能，也评价了模型在高通量筛选方面的良好性能。