Fig. 1.

Discovery of (−)-englerin A (EA) as a novel potent and efficacious TRPC4/5 channel activator. a Chemical structure of EA (Akbulut et al. 2015). b–d Measurements of the free intracellular calcium ion (Ca²⁺) concentration shown as the change (Δ) in fura-2 fluorescence. b Concentration–response data for EA in HEK cells over-expressing TRPC4 (HEK-TRPC4) indicating the 50 % maximum effect (EC₅₀) at 11.2 nM (Akbulut et al. 2015). c As for b except the cells were genetically modified HEK 293 cells induced to over-express TRPC5 (HEK-TRPC5). The fitted curve is a Hill equation indicating an EC₅₀ of 7.59 nM (Akbulut et al. 2015). d Mean responses after 4 min exposure to vehicle, 1 µM EA, or 1 µM EA in the presence of 5 µM ML204 (Akbulut et al. 2015). e Whole-cell current–voltage relationship of membrane current from a single A498 cell during ramp changes in membrane voltage from −100 to +100 mV applied every 10 s. 100 nM EA or its vehicle were bath-applied (Akbulut et al. 2015). f As (e) except with genetically modified HEK 293 cells induced to over-express TRPC4 and transiently express TRPC1 (HEK C4 + C1) (Akbulut et al. 2015)