Fig. 9.

Volume of mitochondria per heart muscle mass across an allometric series. These data were adapted from Hoppeler et al. (36) and reveals that mitochondrial volume is fixed at ∼21% in cardiac cells across species. Benson (13) found that 14% of the wet weight of the heart is noncollagen protein. This corresponds to 140 mg of cellular protein per gram of heart wet weight. With the use of the volume fraction of 21% and assuming a similar density of protein across different cell compartments, a value of ∼30 mg of mitochondria protein per gram of heart is calculated. Since there is ∼1 nmole cyto a/mg mitochondria protein (see results), the data from Hoppeler et al. (36) predicts a cyto a content of ∼30 nmole cyto a/gram of heart, which is in good agreement with the values presented in Table 2.