Correlation between the TRPC6/7 currents and the decay of PI(4,5)P₂. (A and B) Example traces of TRPC6 currents (top) and FRET of PI(4,5)P₂ sensor (CFP_mse-PHd and YFP_mse-PHd) (bottom) upon stimulation with 100 µM CCh of either endogenous (A) or overexpressed M₁R (B). (C and D) Same as in A and B, but in cells expressing TRPC7. (E) Summary of currents and FRET changes. TRPC6/7 current increase (Δ10–90%) and decay (Δ90–50%), kinetics of FRET reduction (τFR), and degree of FRET reduction (FR_min) were accelerated in a CCh concentration and M₁R expression-dependent manner. The data depicted by the stripe and the white bars show without channel expression (transfected only PI(4,5)P₂ sensor) and endogenous receptor simulation, respectively. Numbers in parentheses indicate the number of cells measured, here and throughout. (F and G) Time courses of the Δ10–90% and Δ90–50% of receptor-operated currents were plotted against the simultaneously measured τFR (F, TRPC6; G, TRPC7). These data were obtained from various concentrations of CCh or level of M₁R expression. The slope with a linear fit highlights a relationship between the time courses and τFR.