Fig. 4.

Reduction in extramitochondrial Ca²⁺ by TRPC3 in HeLa cells or in isolated liver mitochondria from Trpc3^−/− mice. (A) Cytosolic Ca²⁺ dynamics ([Ca²⁺]_cyto) in HeLa cells transfected with control vector (CTRL), WT-TRPC3, and TRPC3 mutants (E630Q or E630K) treated with 10 μM histamine in the absence of extracellular Ca²⁺ were monitored by changes in Fura 2 fluorescence. Representative traces from a single experiment (Left) and means ± SEM of peak [Ca²⁺]_cyto changes normalized to CTRL of four independent experiments (Right) with the total number: CTRL, n = 58; WT-TRPC3, n = 50; E630K, n = 58; E630Q, n = 27. *P < 0.05, **P < 0.01 vs. CTRL, ^#P < 0.001 vs. WT-TRPC3. (B–D) Reduction of medium Ca²⁺ by isolated liver mitochondria from WT and Trpc3^−/− mice. Purified liver mitochondria were incubated in a Ca²⁺-free buffer in the presence of Fluo-5N (1 µM). Ca²⁺ was added at a final concentration of 10 (B), 50 (C), or 100 μM (D) and changes in extramitochondrial [Ca²⁺] monitored by Fluo-5N fluorescence for 65 s. Shown are representative traces of time courses of relative fluorescence changes (Left) and means ± SEM (n = 4) of overall Ca²⁺ uptake during the entire experimental period, normalized to that of WT. *P < 0.05 vs. WT.