Stimulation of the rat liver mitochondrial inner-membrane anion-conducting channel by aeration is dependent on the concentration of Ca2+ ions in the assay medium. Ca2+ activates anion conduction in both aerated and non-energised mitochondria but acts over a wider concentration range *+ and produces a greater increase in anion-conductivity in aerated mitochondria. EGTA reverses Ca stimulation but takes several seconds to act, *+ indicating slow release of Ca from the activation site possibly on the matrix side of the inner mitochondrial membrane. It is suggested that this channel may respond to hormone-induced changes in cytosolic Caz+ concentration.

No abstract

Zinc is a potent reversible inlubitor of the pH-dependent anion-conductmg channel m the mitochondrial inner membrane, 50% inhibition was produced by 1.5 PM added Zn" at which point free Zn" was 5 10~8 M. Inhibition by Zn" IS rapid but can be prevented or rapidly reversed by excess EDTA. Concentrations of Zn" higher than 4 PM caused reversal of inhibition to a variable extent depending on the anion. Under these conditions Zn*' did not inhibit ribose entry, the phosphate transporter, or the pH-Insensitive component of the NO,-uniport.

No abstract