To involvement the conformation of the adenine nucleotide translocase in opening the Tl+-induced permeability transition pore in Ca2+-loaded rat liver mitochondria

- The involvement of ANT conformation in Tl+-induced mitochondrial pore is proposed.
- Thiol reagents (PAO, tBHP, DIDS) fixing the ANT in 'c' conformation researched
- Ability of ADP to inhibit the pore decreased in the presence of the reagents.
- N-ethylmaleimide (NEM) reacting with Cys56 of ANT inhibited the pore opening.
- CsA and NEM recovered ability of ADP to inhibit the pore stimulated by the reagents.

The conformation of adenine nucleotide translocase (ANT) has a profound impact in opening the mitochondrial permeability transition pore (MPTP) in the inner membrane. Fixing the ANT in 'c' conformation by phenylarsine oxide (PAO), tert-butylhydroperoxide (tBHP), and carboxyatractyloside as well as the interaction of 4,4′-diisothiocyanostilbene-2,2′-disulfonate (DIDS) with mitochondrial thiols markedly attenuated the ability of ADP to inhibit the MPTP opening. We earlier found (Korotkov and Saris, 2011) that calcium load of rat liver mitochondria in medium containing TlNO3 and KNO3 stimulated the Tl+-induced MPTP opening in the inner mitochondrial membrane. The MPTP opening as well as followed increase in swelling, a drop in membrane potential (ΔΨmito), and a decrease in state 3, state 4, and 2,4-dinitrophenol-uncoupled respiration were visibly enhanced in the presence of PAO, tBHP, DIDS, and carboxyatractyloside. However, these effects were markedly inhibited by ADP and membrane-penetrant hydrophobic thiol reagent, N-ethylmaleimide (NEM) which fix the ANT in 'm' conformation. Cyclosporine A additionally potentiated these effects of ADP and NEM. Our data suggest that conformational changes of the ANT may be directly involved in the opening of the Tl+-induced MPTP in the inner membrane of Ca2+-loaded rat liver mitochondria. Using the Tl+-induced MPTP model is discussed in terms finding new transition pore inhibitors and inducers among different chemical and natural compounds.