Figure 4.

Histamine (HA)-induced internalization of H₁R. BRET measurements in HEK293T cells transiently co-expressing H₁R-Rluc8 (0.5 µg plasmid/dish) in combination with the early endosome marker Venus-Rab5a (2 µg plasmid/dish) in real time upon stimulation with 10 µM histamine (A). Data are shown as mean ± SD from at least three independent experiments performed in triplicate. Area under the curve (AUC) of 1-h BRET traces in response to 10 µM histamine following 30-min pretreatment of the cells with vehicle (control), 1 µM UBO-QIC, 3 µM cmpd101, or 0.16 µM sucrose, or co-transfection with dominant negative dynamin mutant K⁴⁴A or β-arrestin1/2 siRNA. AUC of the BRET experiments are presented as mean ± SD from three independent experiments performed in triplicate, with scatter plots (gray dots) showing the individual AUC values (B). Statistical differences (p < 0.05) compared to vehicle-pretreated (i.e., control) cells were determined using one-way ANOVA with Dunnett’s multiple comparison test and are indicated by an asterisk.