Total Cytochrome Oxidase Activity and its Relation to Basal and Maximal Metabolism

Abstract

THE study of the values of the basal metabolic rate in mammals and its relation to body-weight has been the object of many papers and reviews since the middle of the nineteenth century. On the other hand, very few data are available concerning the upper limit of animal metabolism; only individual values are found in the literature concerning the maximal metabolism of some mammals and man. The incompleteness of the available data and their suitability for comparative purposes are connected with the difficulty in obtaining the state of maximal performance in animals. In addition, in many of the animals used, maximal oxygen consumption can be obtained only under simultaneous application of work and lowered temperatures, so that the working and thermoregulatory capacity of the animals are used as well. In these conditions, however, a rapid decrease of metabolism occurs as a result of cooling the animals, as I have already shown¹; it is very difficult, therefore, to find out the period of greatest oxygen consumption. Nearly all the data in the literature seem to be affected by this error, and the results obtained are, therefore, probably lower than true maximal values.