A theoretical analysis of the effect of phosphate on apparent H+/O stoichiometries in oxygen-pulse experiments with rat liver mitochondria.
It is now generally accepted that, in oxygen-pulse experiments on rat-liver mitochondria suspended in KCl-based media, the rapid import of H+ with phosphate leads to an approx. 33% lowering of apparent H+/O stoichiometry. However, in low-K+ media, N-ethylmaleimide has no effect on stoichiometry, and there appears to be no import of H+ with phosphate. In this paper the quantitative effect of extramitochondrial phosphate on apparent H+/O stoichiometry is calculated theoretically, on the basis of internal and external buffering powers. The lack of appreciable phosphate uptake in low-K+ media is quantitatively explained in terms of several factors, including the initial pH gradient and initial phosphate distribution.
D000818:Animals; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008433:Mathematics; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats
D010710:Phosphates; D010100:Oxygen