Increased Susceptibility of Gracilinanus microtarsus Liver Mitochondria to Ca²⁺-Induced Permeability Transition Is Associated with a More Oxidized State of NAD(P)

Figure 3

Effect of mitochondrial permeability transition (MPT) inhibitors on the Ca²⁺ retention capacity of mouse and marsupial liver mitochondria. Isolated mouse and marsupial liver mitochondria (LM; 0.5 mg/mL) were incubated in standard reaction medium supplemented with NADH-linked (2 mM malate, 1 mM pyruvate, 1 mM α-ketoglutarate, and 1 mM glutamate) respiratory substrates and 0.2 μM Calcium Green-5N. Some experiments were conducted in the presence of the MPT inhibitors: 1 μM cyclosporin A (CsA), 200 μM ADP, or 200 μM ATP plus 3 mM MgCl₂, as indicated in the figure. (a) Representative experiments for estimation of calcium retention capacity of mouse and marsupial liver mitochondria in the presence of ADP. (b) To assess the mitochondrial Ca²⁺ retention capacity, pulses of Ca²⁺ (5 μM for control conditions or 30 μM for the conditions in the presence of MPT inhibitors CsA, ADP, or ATP plus Mg²⁺) were added until mitochondrial Ca²⁺ release occurred. The sum of Ca²⁺ pulses prior to MPT pore opening was taken as the mitochondrial Ca²⁺ retention capacity ( for all conditions except for “ATP+Mg²⁺,” where ). versus respective condition in mouse mitochondria.

(a)

(b)