Figure 1.

Ca²⁺uptake increases liver mitochondrial oxidative phosphorylation supported by pyruvate plus malate. Isolated mouse liver mitochondria (600 μg) were incubated with 1 mM pyruvate + 1 mM malate. A, representative Ca²⁺ uptake curves using Ca²⁺Green 5N to measure extramitochondrial Ca²⁺ in the presence of low Ca²⁺ (2.4 ± 0.6 μM, gray line), medium Ca²⁺ (22.0 ± 2.4 μM, blue line), and high Ca²⁺ (52.9 ± 2.5 μM, purple line) concentrations. B–D, representative O₂ consumption rate (OCR) traces using a high-resolution Oxygraph-2k (O2k) respirometer in response to zero Ca²⁺ (B), low Ca²⁺ (C), and medium Ca²⁺ (D) additions, followed by injection of 1 mM ADP, 1 μM oligomycin (oligo), and 0.5 μM CCCP. E, state 3, after ADP addition. F = 8.059, p = 0.0554, ∗p = 0.0352 versus zero Ca²⁺. F, state 4, after oligomycin addition. F = 14.16, p = 0.0186, ∗p = 0.0195 (low versus zero Ca²⁺) and 0.0355 (medium versus zero Ca²⁺). G, maximal respiration after CCCP addition. F = 17.67, p = 0.0144, ∗p = 0.0153 versus zero Ca²⁺. H, respiratory control ratios (RCR, state 3/state 4). F = 5.708, p = 0.0768, ∗p = 0.0456 versus zero Ca²⁺. I, RCR in the presence of low Ca²⁺ and 10 μM CGP-37157 (CGP) or 10 μM ruthenium red (RuRed). F = 6.369, p = 0.1032, ∗p = 0.0312 versus zero Ca²⁺. n = 4 independent experiments. One-way ANOVA followed by Šidak. J, Ca²⁺ retention capacity (CRC) under control conditions (Ctrl) and in the presence of CGP. K, CRC with cyclosporin A (CsA) in the absence or presence of CGP.