Scaling mitochondrial volume in heart to body mass

The heart mass was measured and the volume density of mitochondria, VV(mt,f), morphometrically estimated in 11 mammalian species ranging from shrew (3 g) to cattle (920 kg). The mass or the volume of the heart muscle (Vh) was found to scale as Mb0 .970 whereas VV(mt,f) scaled as Mb-0.044. Hence, the total volume of mitochondria in heart, V(mt), scaled as Mb0 .927 (V(mt) = VV(mt,f) x Vh). The volume of heart mitochondria was found to scale disproportionately to VO2max ( Mb0 .75) but in proportion to resting cardiac work rate ( Mb0 .9).