2.2. Pharmacological chemicals
Fentanyl (purity, >99%) was obtained from the National
Institute of Food and Drug Control (Beijing, China). Morphine
hydrochloride was purchased from Qinghai Pharmaceutical Factory (Xining,
China). A GRK2 inhibitor was
purchased from Sigma-Aldrich (St. Louis, MO, USA). All chemicals were
dissolved in distilled water. DAPI was purchased from ServiceBio
Technology Co., Ltd. (Wuhan, China), and 4% paraformaldehyde-fixed
solution was purchased from ApplyGen Technology Co., Ltd. (Beijing,
China). Triton X-100 was purchased from SeaskyBio Innovation Technology
Co., Ltd. (Beijing, China). Fetal bovine serum was purchased from Excell
Bio-Technology Co., Ltd. (Taicang, China).