Figure 4.

Functional expression of transfected TRPP2/TRPC1 in mIMCD3 kidney cells. (A–D) Oxo-M-induced normalized currents in (A) untransfected cells and in cells expressing (B) m1AChR/TRPP2, (C) m1AChR/TRPC1 and (D) m1AChR/TRPP2/TRPC1. Currents were recorded using a voltage clamp ramp protocol. Oxo-M, 10 μM; amiloride, 500 μM. Each panel represents the mean±SEM of 5–7 cells. (E–H) Mean I–V relationships for basal currents (black), Oxo-M-induced current (green) and post-amiloride current (red) in (E) untransfected cells and in cells expressing (F) m1AChR/TRPP2, (G) TRPC1 and (H) TRPP2/TRPC1. Black, green and red arrows in (A–D) indicate the time points at which I–V curves were taken. (I–K) Summary data of normalized currents before the application of (I) 10 μM Oxo-M (basal), (J) net Oxo-M-induced inward currents and (K) percentage block of maximum current (after application of Oxo-M) by amiloride (500 μM) obtained from untransfected cells (1), TRPP2 (2), TRPC1 (3) or TRPP2/TRPC1 (4) expressing mIMCD3 cells (n=5–7). The red lines indicate current densities of untransfected cells. ^*P<0.05. (L,M) I–V curves derived from cells co-transfected with TRPP2 (n=7), TRPC1 (n=7) or TRPP2/TRPC1 (n=7) in the presence of (L) 135 mM extracellular Na⁺ or (M) 10 mM CaCl₂. (N) Na⁺ and Ca²⁺ permeability profiles of TRPP2, TRPC1 and TRPP2/TRPC1 in mIMCD3 cells. mIMCD, murine inner medullary collecting duct; Oxo-M, oxotremorine-M; TRP, transient receptor potential.