Modulation of the mitochondrial megachannel by divalent cations and protons.

In patch-clamp experiments on rat liver mitoplasts, the 1.3 nanosiemens (in 160 m M KCl) mitochondrial megachannel was activated by Ca2+ and competitively inhibited by Mg+, Mn2+, Ba2+, and Sr2+.Cyclosporin A, which inhibits the megachannel, also showed a competitive behavior ver.9248Ca2+.The pore is regulated by pH in the physiological range; lower pH values cause its closure in a Ca2+-reversibll manner.The modulating sites involved in these effects are located on the matrix side of the membrane.