Translocation of some Anions Cations and Acids in Rat Liver Mitochondria

Abstract

Studies of net translocation of various anions and cations and their corresponding acids and bases, using extensions of established techniques, imply that the M phase of the cristae membrane of rat liver mitochondria is very impermeable ( i.e. not permitting net permeation) to the following ions: CH 3 COO − , H 2 PO 4 − , HPO 4 2− , SO 4 2− , Fe(CN) 6 3− , Fe(CN) 6 4− , choline + , K + , Na + and NH 4 + . How‐ever, the M phase appears to be permeated rapidly by SCN − and slowly by Cl − . It has been confirmed that CH 3 COO − and NH 4 + probably permeate as CH 3 COOH and NH 3 respectively, and that phosphate equilibrates across the M phase by an electrically neutral mechanism equivalent to H 3 PO 4 translocation. The possibility that phosphate is obligatorily translocated as KH 2 PO 4 has been eliminated. Sulphate equilibrates by an electrically neutral mechanism equivalent to H 2 SO 4 translocation. The alkali metals Na + and K + (and possibly NH 4 + ) equilibrate across the M phase via specific electrically neutral H + /Na + and H + /K + antiport, the former being the more active at neutral pH. Choline does not participate significantly in proton‐coupled antiport.