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Britton Chance coauthored measurements of oxygen utilization during oxidative phosphorylation. Time-dependent oxygen signals reveal how respiration responds to changes in the available substrates and phosphorylation conditions.

The apparatus must separate genuine oxygen consumption from oxygen ingress and instrumental response. Such controls connect a measured signal slope with a physiological flux.^[ref]

Identity and biography: archives.upenn.edu/exhibits/penn-people/biography/britton-chance/

G. R. Williams coauthored kinetic measurements of oxygen utilization with Britton Chance. The work relates the time course of mitochondrial respiration to the conditions controlling oxidative phosphorylation.

A bulk oxygen concentration records the balance of consumption and exchange with the environment. Interpreting its slope therefore requires both biochemical and instrumental controls.^[ref]

G. R. Williams coauthored research on oxidative phosphorylation with Britton Chance.

Publication record: pubmed.ncbi.nlm.nih.gov/13271402/

In Respiratory enzymes in oxidative phosphorylation. I. Kinetics of oxygen utilization (1955), Britton Chance and G. R. Williams examined isolated liver mitochondria in isotonic medium with substrate and inorganic phosphate. A one-millilitre optical cuvette held the suspension. A vibrating platinum electrode lay outside the light path; calibrated electric current followed dissolved oxygen, with rapid changes recorded by a galvanometer oscillograph. Air-saturated and oxygen-depleted readings checked sensitivity. Their Figure 2 shows ADP additions accelerating oxygen consumption, followed by return to slow respiration; repeated additions restored acceleration. Figure 4B compares delayed substrate addition after ADP incubation with the reverse order, supporting little unrelated ADP loss in that preparation. These comparisons support coupling to ADP utilization. The authors discuss dilution, sensitivity changes and atmospheric oxygen entry, which especially biases slow respiration. The readout did not directly measure the membrane potential or prove the later chemiosmosis mechanism.^[ref]

A control can test either the instrument or the biology. Calibrating electric current against oxygen checks the former; comparing responses before and after an ADP addition checks the latter. A valid calibration cannot by itself establish ATP formation, and a repeatable biological response cannot by itself fix an instrument's sensitivity.

The respiratory control ratio divides the oxygen consumption rate during ADP-stimulated respiration by that after supplied ADP has been used. It compares reaction rates, not ATP formed per oxygen.^[ref]

A large ratio means strong stimulation under the comparison's conditions; it is not a universal measure of all mitochondrial functions.

For a constructed example, choose constant suspension volume $V=2\mathrm{mL}$ and oxygen concentration declines of $0.030$ and $0.006\mathrm{mmol}{\mathrm{L}}^{-1}\mathrm{mi}{\mathrm{n}}^{-1}$ during the two comparison windows. Assume no gas exchange or dilution and a correctly calibrated readout. A derivative converts each concentration slope into an amount of substance consumption rate:The common volume cancels in the ratio, so dividing the positive slope magnitudes gives the same answer. These are chosen inputs, not the 1955 observations. If an uncorrected influx of $3\mathrm{nmol}\mathrm{mi}{\mathrm{n}}^{-1}$ of oxygen occurred in both windows, the apparent rates would instead be $57$ and $9$, giving $19/3\approx 6.33$. The same absolute error can inflate a ratio because it removes a larger fraction of its smaller denominator.

Respirometry measures gas exchange associated with metabolism, commonly oxygen consumption or carbon-dioxide production. In a closed chamber, the change in gas amount over time can estimate a rate after correcting for chamber volume, background and temperature. Flow systems instead compare incoming and outgoing gas. A measured oxygen flux reports aggregate oxidative activity under the stated conditions; it does not uniquely identify which fuel or individual reaction produced it. ^[ref]