Fig. 3. Typical examples of measurement of Ca2+-induced mitochondrial permeability transition pore opening on isolated heart mitochondria (protocol 1). The calcium uptake by mitochondria (5 mg protein in 1 ml) was measured in the presence of 5 mm succinate by using a specific calcium electrode. Equivalent pulses of CaCl2(4 nmol Ca2+/mg protein = 20 μm) were added to mitochondria every 1 min until a spontaneous release of Ca2+occurred. Mitochondrial preparations were from the sham 1 (A ), ischemic (B ), desflurane (C ), and ischemic preconditioning (D ) groups.