Figure 5. Constitutive activity of the TRPC3_T635A moonwalker (mwk) mutant is antagonized by Trpc1 expression.

(A, B) Changes of cytoplasmic Ca²⁺ (F340/F380) in cultured cortical astrocytes isolated from wild-type (wt) and heterozygous TRPC3_T635A moonwalker (mwk) mice in the presence (A), absence (B, 0–100 s) and after addition (B, application bar) of extracellular Ca²⁺. (C) Basal cytoplasmic Ca²⁺ (F340/F380) in A and ΔF340/F380 upon Ca²⁺ readdition in B. (D–G) Spontaneous inward and outward currents at −80 mV and +80 mV in the tetracycline-inducible HEK TRPC3_T635A (mwk) cell line. Control, no tetracycline induction; mwk, after tetracycline induction; mwk+C1, after tetracycline induction and transfection with the Trpc1 cDNA. Current-voltage relationships at break in (E) and at 150 s (F) and corresponding current amplitudes at −80 mV and +80 mV (G), plotted as means ± S.E.M. (n, number of cells). (H, I) Basal cytoplasmic Ca²⁺ and increase of cytoplasmic Ca²⁺ upon addition of 2 mM extracellular Ca²⁺. Control, no tetracycline induction; mwk, after tetracycline induction; mwk+C1, after tetracycline induction and transfection with the Trpc1 cDNA. Cytoplasmic Ca²⁺ at 40 s and at 400 s (I) plotted as mean ± S.E.M. (n, number of cells from x, number of experiments (n/x)). Asterisks assign significant differences (* P<0.05, ** P<0.01, *** P<0.001, ns = not significant).