Fig. 3. Calcium does not open the MPTP in A. franciscana. Upper frame, presence or absence of swelling induced by calcium plus phosphate in isolated mitochondria from post-diapause embryos of A. franciscana and rat liver. Mitochondrial absorbance (a.u.) at 540 nm (inversely related to swelling) was measured after addition of 1 mmol l^–1 calcium to A. franciscana mitochondria and 0.1 mmol l^–1 to rat liver mitochondria. Mitochondria were energized with 5 mmol l^–1 succinate. Lower frame, Western blot analysis showing lack of cytochrome c (cyt-c) release from A. franciscana mitochondria in response to calcium. Blots were probed with cyt-c antibody. Cyt-c Std, positive control, purified horse heart cyt-c; Mito. extract, positive control, supernatant from homogenized mitochondria; Control supern., supernatant from energized mitochondria without Ca²⁺ addition; Plus Ca²⁺, supernatant from energized mitochondria plus 1 mmol l^–1 Ca²⁺ (modified from Menze et al., 2005b).