= Respiratory control ratio
{title2=$\mathrm{RCR}=v_{\rm ADP}/v_{\rm after}$}
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>.<Respiratory enzymes in oxidative phosphorylation. I. Kinetics of oxygen utilization by Britton Chance and G. R. Williams>[pp. 386–387, Figure 2 and discussion of the ratio of respiration rates with and without ADP]{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 (thermodynamics)> $V=2\,\mathrm{mL}$ and <oxygen> <concentration> declines of $0.030$ and $0.006\,\mathrm{mmol\,L^{-1}\,min^{-1}}$ 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:
$$
v=-V\frac{dc_{\mathrm O_2}}{dt},\qquad
v_{\rm ADP}=60\,\mathrm{nmol\,min^{-1}},\qquad
v_{\rm after}=12\,\mathrm{nmol\,min^{-1}},\qquad
\mathrm{RCR}=5.
$$
The common <volume (thermodynamics)> 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 $3\,\mathrm{nmol\,min^{-1}}$ of <oxygen> occurred in both windows, the apparent rates would instead be $57$ and $9$, giving $19/3\approx6.33$. The same absolute error can inflate a ratio because it removes a larger fraction of its smaller denominator.
Back to article page
