The calorimetric-respirometric ratio

In most cases, scientists that wish to investigate intermediary metabolism in tissues choose indirect calorimetry, OUR, as one of their analytical tools and perhaps also measure lactate concentrations as an indicator of the intensity of aerobic glycolysis. Even when needing to express the results in terms of heat flux, for respiratory metabolism they apply the appropriate oxycaloric equivalent,, to the data for oxygen flux ), 

Oxycaloric equivalents are the theoretical values for the enthalpy changes of the catabolic half-cycle, e.g. glc to HCOj and H, and do not include any coupled processes such as ATP production. This means that no work is done, so 

Oxycaloric equivalents of aerobic respiration for various substrates in aqueous solution at pH 7. 

The theoretical oxycaloric equivalent is the expected ratio of the calorimetric heat flux and the respirometric oxygen flux, the CR ratio. 

Similar equations can be constructed for other anaerobic products (p) in a generalised equation, p can be substituted for Lac and, if there is more than one 

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Kemp, R.B. (1990). Importance of the calorimetric-respirometric ratio in studying intermediary metabolism of cultured animal cells. Thermochim. Acta 172,61-73. 

Figure 56. Comparison of the viable cell concentration measured by the on-line capacitance signal with oxygen flux and the calorimetric-respirometric (CR) ratio in a batch culture of growing CHO320 cells. The medium was buffered by...

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