Figure 1.

Apigenin stimulates TRPV4-mediated cation current in TRPV4-over-expressing HEK cells. (A) Representative immunoblot probed with anti-TRPV4 and anti-β-tubulin (n = 3). Left, vector-transfected HEK cells; right, TRPV4-transfected HEK cells. (B) upper panel, representative time course of whole-cell current in a TRPV4-over-expressing HEK cell. Current was sampled every 10 s at +80 and −80 mV. Apigenin and ruthenium red (RuR) were applied to the bath at the time points indicated by the filled circles and the arrow. Lower panel, representative traces showing voltage protocol and corresponding whole-cell currents of apigenin in HEK cells over-expressing TRPV4. (C) Left panel, current–voltage relationships as in (B). Right panel, plot of concentration–response with curve fitting to determine the apigenin EC₅₀. (D) Summary data showing the whole-cell current in response to apigenin in the presence of TRPV4 blockers RuR (5 µM) or RN1734 (6 µM) or HC067047 (0.5 µM) (15–30 min incubation before apigenin application). Vehicle, 0.1% DMSO. (E) Current–voltage relationships in vector-transfected HEK cells. Values are presented as mean ± SEM (n = 5–8). ^#P < 0.05 compared with apigenin. *P < 0.05 compared with vehicle.