MITOCHONDRIAL PROTON CONDUCTANCE AND H+ O RATIO ARE INDEPENDENT OF ELECTRON-TRANSPORT RATE IN ISOLATED HEPATOCYTES/

In this paper we examine the non-linearity of the relationship between the proton electrochemical gradient across the mitochondrial inner me mbrane (Delta p) and oxygen consumption of non-phosphorylating mitocho ndria in situ in hepatocytes. Models proposing to explain the non-line ar relationship were tested experimentally. It was shown that the mito chondrial proton conductance and the number of protons pumped to the c ytosolic side of the mitochondrial inner membrane by the electron tran sport complexes per oxygen atom consumed (H+/O ratio) are independent of electron transport rate in mitochondria in isolated hepatocytes. Th e non-linearity of the plot of Delta p against the non-phosphorylating oxygen consumption is due to either a potential-dependent slippage of the proton pumps of the mitochondrial inner membrane and/or a potenti al-dependent leakage of protons back across the mitochondrial inner me mbrane.