Calorimetric & respirometric monitoring of metabolism: some Examples

inTroDuCTion Simultaneous measurements of the rates of heat production and oxygen utilisation by living tissues provides a direct quantitative means of detecting subtle changes in metabolic state in the face of altered physiological and environmental conditions. The ratio of calorimetrically measured heat flux to the respirometrically measured oxygen flux is often called the “calorimetric-respirometric ratio” or CR ratio. This can be used to partition total metabolic energy flux into its aerobic and anaerobic components by comparison of the experimental CR ratio with the theoretical “oxycaloric equivalent” for fully aerobic respiration. Such information is most important when evaluating the physiological effect of environmental stress. Industrialisation of many processes has lead to an increasing amount of synthetic and natural waste products expelled into the environment The consequences of this can often be fatal as seen by the many examples of polluted rivers, waste land and the atmosphere. This large amount of waste can be seen to be harmful to the ecosystem and has lead to an imbalance of the natural flora and fauna. There is a need, therefore to study the effects of pollutants and to evaluate quantitatively their toxicological effects. The combined use of microcalorimetry and respirometry provides a useful means of monitoring such effects.