Oxygen consumption and cellular ion transport: evidence for adenosine triphosphate to O2 ratio near 6 in intact cell.

Oxygen (O2) consumption and net K+ uptake were measured simultaneously upon reintroduction of K+ into a K+-depleted suspension of renal tubules. The K+/O2 stoichiometries of 11.8 +/- 0.2 and 8.4 +/- 0.6 were obtained for reduced nicotinamide adenine dinucleotide- and flavoprotein-linked substrates, respectively. These values complement classical K+ to adenosine triphosphate (ATP) and ATP/O2 stoichiometries, thereby demonstrating a remarkably efficient coupling between the processes of Na+- and K+-dependent adenosinetriphosphatase-mediated ion transport and oxidative phosphorylation within the intact cell.