Fig. 2. Histamine-induced [Ca²⁺]_i signals were inhibited by dexmedetomidine. (A) Expression levels of histamine receptors mRNA (H1R to H4R) in HeLa cells. (B) Changes in [Ca²⁺]_i induced by 100 nM histamine. (C) Changes in [Ca²⁺]_i after pretreatment with 10 ng/mL dexmedetomidine (Dex) and subsequent treatment with 100 nM histamine. (D) Changes in [Ca²⁺]_i after pretreatment with 10 µM histamine (E) Changes in [Ca²⁺]_i after pretreatment with 100 ng/mL dexmedetomidine and subsequent treatment with 10 µM histamine. The upper bars indicate the extracellular solutions applied to the cells and traces were selected randomly. Three separate experiments were performed and each point represents a mean±SEM. (-): no RNA, M: DNA ladder (bp).