Proposed contribution of PI(4,5)P₂ reduction in receptor-operated TRPC6/7 currents. (A) Representative SPD model simulations for receptor-operated TRPC6 currents (top) and FRET by PI(4,5)P₂ sensor (bottom) from various PLC activities (k_i). k_i varied from 0.03 to 1.0 (s⁻¹). The same color curves displayed in each panel were calculated from the same k_i value. (B) The various kinetics of PI(4,5)P₂ reduction (τFR) according to the changes in PLC activity (k_i) impact activation (left; Δ10–90%) and inactivation (right; Δ90–50%) of TRPC6/7 channel currents. Shown are the prediction made by the DG model (black) and the SPD model (red) for TRPC6 (circles) and TRPC7 channels (triangles). The star in the panels indicates the result from the k_i setting of 0.7. The solid and dashed lines indicate the current–τFR relationships experimentally observed in TRPC6 and TRPC7, respectively. The direction of the arrows and its size indicate the gap from the DG to SPD model. (C) Simulation results of PLC-dependent characteristics of TRPC6/7 channels by DG (black) and SPD (red) models. (Left) The relationship between maximum open probability (P_omax) and k_i. (Middle) The time required to peak currents (s) and k_i. (Right) The total ionic influx and k_i. t = 30 s.