Varying effects of calcium on the oxidation of palmitate and alpha-ketoglutarate in isolated rat liver mitochondria incubated in KCl-based and sucrose-based media.
Isolated mitochondria from rat liver were incubated in the presence of [U-14C]palmitate, ATP, CoA, carnitine, EGTA (ethylene glycol bis (beta-aminoethyl ether) N,N'-tetraacetic acid) and varying amounts of calcium. When a KC1-based incubation medium was used, the oxidation of palmitate was inhibited when the concentration of free calcium was increased from about 0.1-10 microM. When a sucrose-based incubation medium was used, the basal rate of palmitate oxidation was about half of that observed with the KC1-medium and calcium had a stimulatory effect. With the KC1-medium the rate of oxygen consumption was inhibited by calcium with alpha-ketoglutarate as well as palmitate as the respiratory substrate. No inhibitory effect of calcium was observed with succinate or beta-hydroxybutyrate. With the KC1-medium and with alpha-ketoglutarate as the respiratory substrate, state 3 respiration but not state 4 respiration was inhibited by calcium. When the sucrose-medium was used, state 3 respiration was first inhibited by calcium, but this inhibition was gradually relieved and the respiratory rate finally became higher than it was before calcium addition.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D066298:In Vitro Techniques; D007656:Ketoglutaric Acids / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013395:Sucrose / Q000494:pharmacology*
D007656:Ketoglutaric Acids; D010169:Palmitic Acids; D019308:Palmitic Acid; D013395:Sucrose; D000244:Adenosine Diphosphate; D011189:Potassium Chloride; D002118:Calcium