Characterization of interactions between local anesthetics and histamine H₁ receptor by cell membrane chromatography...

Local anesthetic has a wide application in clinical practice. However, angioedema, an adverse reaction caused by local anesthetics, has been reported to be related to histamine H₁ receptor (H₁R). Hence, an effective and practical method for investigating the interaction characteristics between local anesthetics and H₁R is needed. In this work, the competition binding assay and the relative standard method based on H₁R-HEK293/cell membrane chromatography (CMC) were developed to analyze the equilibrium dissociation constant (K_D) values of local anesthetics with H₁R. The activity of drugs toward H₁R was evaluated by intracellular Ca²⁺ imaging assay. Molecular docking was used to verify the interaction modes that occurred at the activate pocket of H₁R protein. Results showed that the local anesthetics can directly occupy histamine binding sites on H₁R, and the K_D values obtained from different CMC methods exhibited positive correlations with each other (p < 0.01). The K_D values of tetracaine, procaine, and lidocaine were much closer to that of histamine than bupivacaine and ropivacaine. This was not only in line with the Ca²⁺ responses in activating H₁R, but also consistent with the same amino acid residues shared with histamine in the H₁R active site. In conclusion, this study provided new insight into the interactions between local anesthetics and H₁R. The H₁R-HEK293/CMC methods developed in this study could be used to evaluate the interaction characteristics of those compounds acting on H₁R.