title: Exchangeable and total calcium pools in mitochondria of rat epididymal fat-pads and isolated fat-cells. Role in the regulation of pyruvate dehydrogenase activity.
abstract: 1. Isolated fat-cells and intact epididymal fat-pads were incubated in medium containing 45Ca2+ and the incorporation of 45Ca into mitochondrial and extramitochondrial fractions was studied. Redistribution of 45Ca between these fractions was essentially prevented by the addition of EGTA [ethanedioxybis(ethylamine)tetra-acetate] and Ruthenium Red to the sucrose-based extraction medium. 2. Incorporation of 45Ca into mitochondrial fractions of both fat-cells and fat-pads was found to be complete within 2-5 min, suggesting that mitochondria contain a pool of calcium in rapid isotopic exchange with extracellular Ca2+. This pool was about 20 times larger in mitochondria within fat-cells than within fat-pads. In fat-cells, 45Ca incorporation into the mitochondrial fraction accounted for about 34% of the total 45Ca incorporation into cells after 20 min and about 50% of the total mitochondrial calcium content measured by atomic absorption; values in fat-pads were about 7 and 20% respectively.
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004140:Dinitrophenols / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004822:Epididymis / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D008094:Lithium / Q000494:pharmacology; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D010710:Phosphates / Q000494:pharmacology; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism; D051381:Rats; D012430:Ruthenium Red / Q000494:pharmacology; D013386:Succinates / Q000378:metabolism; D013997:Time Factors
chemical_list: D004140:Dinitrophenols; D007328:Insulin; D010710:Phosphates; D011768:Pyruvate Dehydrogenase Complex; D013386:Succinates; D012430:Ruthenium Red; D000001:Calcimycin; D004533:Egtazic Acid; D008094:Lithium; D005969:Glutamate Dehydrogenase; D002118:Calcium; D004837:Epinephrine