Biogenesis of mammalian mitochondria in the renoprival kidney: I. Amino acid incorporation and respiratory activity

Abstract

Changes in the yield of mitochondrial protein, in the incorporation of leucine into mitochondrial proteins, and in the respiratory activity of isolated mitochondria were determined in the remaining kidney (renoprival kidney) of the rat during the first 72 hr postmononephrectomy. At 24, 48, and 72 hr the yield of mitochondrial protein isolated from the renoprival kidney increased 13, 23, and 34%, respectively, whereas renal mass increased 9, 14, and 19%. Incorporation of [ 3H]-leucine in vivo into total mitochondrial protein was increased 96 and 130% over control at 12 and 24 hr, respectively. Incorporation of leucine in vitro by mitochondria was increased 27% over control at 24 hr; chloroamphenicol, but not cycloheximide, inhibited the in vitro incorporation. At 24 hr, the rate of O 2 consumption (state 3) was decreased, but P O ratios, respiratory control values, and glutamic and succinic dehydrogenase activities were unaltered. The content of pyridine nucleotide, cytochromes a, a 3, and c was decreased at this time; these activities approached normal values by 72 hr. The results suggest that during the 24 and 48 hr postmononephrectomy there is an increase in mitochondrial protein and specific changes in mitochondrial function which may be indicative of a proliferation of mitochondria in the renoprival kidney. This system should be valuable in investigating the events involved in mitochondrial biogenesis in mammalian cells.