Calcium transport by rat brain mitochondria and oxidation of 2-oxoglutarate.
Contrary to previous reports brain mitochondria have a substantial capacity for net Ca2+ uptake (approx. 1.2 mueq. Ca2+ per mg protein) providing succinate is the oxidizable substrate. ATP stimulates calcium uptake (to 1.8 mueq. per mg protein), but is not required. The accumulation of Ca2+ with NAD-linked substrates is, however, significantly less. With 2-oxoglutarate, very limited Ca2+ uptake occurs before respiration is inhibited. At low concentrations (10 microM), Ca2+ stimulates the 2-oxoglutarate dehydrogenase activity of detergent solubilized mitochondria. Millimolar [Ca2+] is required for inhibition. Therefore, Ca2+ inhibition of 2-oxoglutarate oxidation can explain the low maximum uptake with this substrate, but probably not by directly effecting the dehydrogenase. Hence, the oxidation of 2-oxoglutarate can be either enhanced or suppressed depending upon the net Ca2+ accumulated by brain mitochondria.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D007655:Ketoglutarate Dehydrogenase Complex / Q000037:antagonists & inhibitors / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D010084:Oxidation-Reduction; D010710:Phosphates / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012168:Retinal Pigments / Q000528:radiation effects*; D012243:Rhodopsin / Q000031:analogs & derivatives / Q000528:radiation effects*; D012710:Serum Albumin, Bovine / Q000494:pharmacology
D007656:Ketoglutaric Acids; D010710:Phosphates; D012168:Retinal Pigments; D012710:Serum Albumin, Bovine; C042970:7,8-dihydrorhodopsin; D000255:Adenosine Triphosphate; D012243:Rhodopsin; D007655:Ketoglutarate Dehydrogenase Complex; D008274:Magnesium; D002118:Calcium