Action of local anaesthetics on passive and energy-linked ion translocation in the inner mitochondrial membrane

The effect of dibucaine on passive and respiration-driven ion translocation and oxidative phosphorylation in submitochondrial particles from beef-heart has been studied.Dibucaine inhibited the nigericin-mediated H⁺/K⁺ exchange diffusion and the electrogenic, valinomycin-mediated K⁺ translocation in submitochondrial particles.The local anaesthetic exerted a direct stimulatory effect on the respiration-driven proton uptake and on the passive proton-diffusion reactions. The increase of the respiration-linked proton turnover caused by dibucaine was accompanied by uncoupling of oxidative phosphorylation. It is concluded that spontaneous noncoupled as well as ionophoremediated K⁺ translocation in mitochondria occurs across phospholipid bilayer regions of the membrane whilst other components of the membrane would be specifically involved in active and passive proton translocation across the membrane.The results indicate that polar groups of membrane phospholipids play an important role in energy conservation and transfer in the mitochondrial membrane.