Synthesis and degradation of mitochondrial components in hypertrophied rat heart.
The accumulation of inner mitochondrial components of rat heart was studied 1 and 3 days after constriction of the ascending aorta of rats. By 1 day after aortic constriction, the activities of three mitochondrial respiratory enzymes/mg of cardiac homogenate protein were increased; after 3 days, specific activities had levelled off or decreased. Selective accumulation of inner mitochondrial membrane components 24h after aortic constriction was further indicated by increased left ventricular cytochrome c concentration (nmol/mg of protein). By 3 days after surgery, cytochrome c concentration was significantly diminished. Low-temperature spectroscopy of isolated mitochondria showed that the ratios of cytochromes c, b and a+a(3) remained unchanged after aortic constriction, suggesting that cytochrome c was a good indicator of the response of the other mitochondrial inner-membrane cytochromes as well. The effect of cardiac hypertrophy on the turnover of cytochrome c was also examined. Cytochrome c was labelled in its haem group with delta-amino[2,3-(3)H(2)]laevulinate 3 days before aortic constriction. By 1 day after surgery the total ventricular radioactivity in cytochrome c of aortic banded animals was significantly higher than in sham-operated controls, indicating a decreased degradation rate in the former during the first postoperative day. delta-Aminolaevulinate was shown to be a particularly suitable precursor for such turnover studies, since it results in rapid pulse-labelling of cytochrome c (peak activity in 90min), is rapidly removed from the precursor pool (t((1/2))=30min) and is not reutilized.
D000818:Animals; D001011:Aorta; D006332:Cardiomegaly / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003250:Constriction; D003579:Cytochrome Reductases / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D007982:Levulinic Acids / Q000378:metabolism; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D013385:Succinate Dehydrogenase / Q000378:metabolism; D014316:Tritium
D003574:Cytochrome c Group; D003580:Cytochromes; D007982:Levulinic Acids; D014316:Tritium; D013385:Succinate Dehydrogenase; D003579:Cytochrome Reductases; D003576:Electron Transport Complex IV