Intraspecies differences in lung metabolism and granular pneumocyte mitochondria

The authors used waltzing and nonwaltzing mice to examine granular pneumocyte mitochondria and lung oxygen consumption and protein synthesis. They found that the oxygen consumption of lung slices from waltzing mice is higher than that of lung slices from nonwaltzing mice. The volume density of granular pneumocyte mitochondria is higher in waltzing than nonwaltzing mice as is their number per 100 mum-3 of cytoplasm. The mean, length, width, volume and surface density of individual mitochondria are the same in both groups. The incorporation of [14-C]leucine by lung slices into protein in a surface active lung fraction is greater in lung slices from waltzing than nonwaltzing mice. This difference occurs in the face of similar levels of free leucine in both groups. The authors conclude that there are intraspecies differences in lung oxygen consumption and protein synthesis and in the volume density and number of granular pneumocyte mitochondria.