Relationship between the electrochemical proton gradient and respiration: pyruvate and l-palmitoylcarnitine as hydrogen donors for rat heart mitochondria.

The electrochemical proton gradient (delta/uH+) and the rate of respiration were determined as function of the work load at conditions where isolated rat heart mitochondria utilize pyruvate and/or l-palmitoyl-carnitine as hydrogen donors. Delta/uH+ was calculated from the distribution of 86Rb+ (delta psi marker) and [14C]-dimethyloxazolidine-2,4-dione (delta pH marker) between the mitochondrial matrix space and the medium. A transition from l-palmitoylcarnitine to pyruvate utilization did not change the rate of hydrogen supply or the mitochondrial energy state.