Measurement of Rhodamine 123 in Three-Dimensional Organoids: A Novel Model for P-Glycoprotein Inhibitor Screening.

P-glycoprotein (P-gp), as the most important efflux transporter in intestines, plays the key role to determine the bioavailability of many drugs. The three-dimensional (3D) organoid model is suitable to imitate small intestinal epithelium. In this study, a rapid, sensitive and efficient method to measure rhodamine 123 (Rh123, P-gp substrate) in 3D organoids was developed to analyse P-gp-mediated drug transport. Ultrasonic cell disruptor was used to smash the organoid, and automatic microplate reader was used for detecting the concentration of Rh123 (λex /λem = 485/520 nm). Moreover, verapamil, quinidine and mitotane were used to make validation about this newly developed approach. All three P-gp inhibitors significantly inhibited the transport of Rh123 into 3D organoids. Therefore, the above-mentioned method could serve as a new model for P-gp inhibitor screening in a high-throughput way.