Ion Transport in Liver Mitochondria

The H + /Ca ++ ratio during the aerobic uptake of Ca ++ by rat liver mitochondria, oxidizing endogenous substrates or succinate, increased with the increase of the Ca ++ /protein ratio. At high protein concentrations an apparent “reuptake” of the H + ejected was observed. Mitochondrial aging also resulted in a decrease of the H + /Ca ++ ratio. Succinate caused a decrease of the H + ejection. The effect of succinate was dependent on the pH and on the concentration of Ca ++ . A binding of succinate to the mitochondria was observed parallel to the decrease of the H + /Ca ++ ratio from 2 to 1. Addition of Ca ++ caused a release of K + which was slow in fresh mitochondria and rapid in valinomycin treated mitochondria. The K + /Ca ++ ratio was 2 in both cases. A H + /Ca ++ ratio of about 2 was usually observed when the aerobic uptake of Ca ++ was started either by the addition of mitochondria to a Ca ++ containing medium or by the addition of succinate to Ca ++ ‐and rotenone‐treated mitochondria.