Fig 8. Spilanthol-induced inhibition of cAMP production is sensitive to [Ca²⁺]_i.

(A) After pretreatment with BAPTA-AM (30 min, 40 μM) neither exposure to spilanthol 100 μg/ml nor to ATP (100 μM) were able to increase intracellular Ca²⁺ level as measured in Fura-2 loaded NKCC2-HEK293 cells. Representative trace of n = 72 cells in 4 different experiments. (B) Under the same experimental condition (BAPTA-AM, 30 min, 40 μM) spilanthol did not inhibit cAMP production induced by either 10 μM isoproterenol or 10 μM forskolin as measured by the 480/535 nm emission ratio of the cAMP/FRET probe. Representative trace of n = 23 cells in 4 different experiments.