Figure 7. .
Effect of histamine receptor subtype agonists on intracellular [Ca2+] ([Ca2+]i) in rat conjunctival goblet cells. Cultured rat goblet cells were loaded with the Ca2+ indicator dye fura 2 and either stimulated with an H1 agonist histamine dimaleate (A), an H2 agonist amthamine (B), an H3 agonist α-methylhistamine (C), or an H4 agonist 4-methylhistamine (D). Peak [Ca2+]i was calculated and shown as mean ± SEM from three independent experiments (A–D). Cultured rat goblet cells were also pre-incubated with H89 (10−6 and 10−5 M) for 30 minutes and stimulated with either amthamine (10−5 M) or VIP (10−7 M) (E). Mean ± SEM of the percent inhibition shown in (E) is from four independent experiments. *Indicates statistical significance from no addition (0). #Indicates statistical significance from amthamine alone.