Abstract
In the presence of oligomycin ADP inhibits the osmotic swelling of the nonenergized rat liver mitochondria in the NH 4NO 3 medium. With the energized mitochondria ADP enhances contraction of the mitochondria swollen in the NH 4NO 3 medium. Carboxyatractyloside and atractyloside abolish or prevent the effects of ADP. The direct measurements of the proton conductance of rat liver mitochondria shows that the inhibitory action of ADP + oligomycin on the H + permeability does not depend on the energization of mitochondria. In these experiments the local anesthetic nupercaine and ADP additively inhibit the inner membrane conductance for protons, but carboxyatractyloside abolishes only the effect of ADP. In the presence of oligomycin ADP also inhibits the osmotic swelling of the nonenergized liver mitochondria in the KNO 3 medium, and the energy-dependent swelling of rat liver mitochondria in the medium with K + ions and P i . The inhibition by ADP of the membrane passive permeability for K + is also sensitive to carboxyatractyloside. It is concluded that rat liver mitochondria possess an ADP-regulated channel for H + and K +. The properties of this pathway for protons and potassium ions favor the idea that ADP regulates the mitochondrial permeability via adenine nucleotide translocase. It is assumed that the adenine nucleotides carrier should operate according to the “gated pore” mechanism.
Published Version
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