title: 14C-labeled substrate catabolism by human diploid fibroblasts derived from infants and adults.
abstract: Untransformed diploid skin fibroblasts from eight normal adults, aged 24 to 74 years, catabolized several 14C-labeled substrates less effectively than cells from ten normal male infants. 14C-labeled substrate metabolism was quantitated either by measuring the evolution of 14CO2 from the 14C-labeled compounds or the incorporation of 14C into cellular protein via transamination of tricarboxylic acid cycle intermediates derived from the 14C-labeled substrates. With these methods, adult cells catabolized [1-14C]butyrate, [1-14C]octanoate, and 1-[2-14C]leucine at rates 44 to 64% of those found in infant cells. The oxidation of [1,4-14C]succinate and [U-14C]malate was identical in both infant and adult cells, while [2,3-14C]succinate catabolism was mildly decreased in adult cells (65-80% of control). These observations parallel those made in rat tissues and confirm that the same phenomenon occurs in cultured human fibroblasts.
mesh_terms: D000328:Adult; D000375:Aging; D002245:Carbon Dioxide / Q000032:analysis; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D011506:Proteins / Q000378:metabolism*; D012867:Skin / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D011506:Proteins; D002245:Carbon Dioxide