Respiratory control and ADP:O coupling ratios of isolated chick heart mitochondria.
Heart mitochondria isolated from 14- to 21-day-old chicks are highly coupled and often have respiratory control ratio (RCR) values exceeding 100. This paper presents data from a study of some of the properties of these mitochondria. The studies show that: (a) The ADP:O ratios and the state 4 rates of respiration are highly dependent upon the concentration of mitochondria at which these parameters are measured. (b) The mitochondrial isolate is contaminated with at least two divalent cation-stimulated ATPase, of which one is the F1F0-ATPase of broken mitochondria. (c) The oligomycin-sensitive component of state 4 respiration is completely inhibited by ethylene glycol bis(beta-amino-ethylether) N,N'-tetraacetic acid (EGTA). This inhibition is biphasic and attributable to the differential affinity of EGTA for Ca(II) and Mg(II). (d) Ca(II) and Mg(II) stimulate state 4 respiration, thereby depressing RCR values. These cations also decrease ADP:O ratios from greater than or equal to 3.25 to 3.0 for some NAD-linked substrates. (e) Uncoupled (i.e., oligomycin-insensitive) state 4 respiration can be abolished by treating the mitochondria with Nagarse and by preincubating mitochondria with exogenous substrate. (f) The ADP:O ratios obtained when these heart mitochondria oxidize pyruvate/malate, alpha-ketoglutarate, and beta-hydroxybutyrate are fractional and significantly greater than 3.0.
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Department of Biochemistry, Michigan State University, East Lansing 48824.
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D020155:3-Hydroxybutyric Acid; D000244:Adenosine Diphosphate / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002645:Chickens; D004533:Egtazic Acid / Q000494:pharmacology; D003576:Electron Transport Complex IV / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D005971:Glutamates / Q000378:metabolism; D006885:Hydroxybutyrates / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D003012:Microbial Collagenase; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010086:Oxidative Phosphorylation Coupling Factors / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D011773:Pyruvates / Q000378:metabolism; D013386:Succinates / Q000378:metabolism
D005971:Glutamates; D006885:Hydroxybutyrates; D007656:Ketoglutaric Acids; D010086:Oxidative Phosphorylation Coupling Factors; D011773:Pyruvates; D013386:Succinates; D004533:Egtazic Acid; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000244:Adenosine Diphosphate; D003576:Electron Transport Complex IV; D003012:Microbial Collagenase; D000251:Adenosine Triphosphatases; D008274:Magnesium; D005033:Ethylmaleimide; D020155:3-Hydroxybutyric Acid