Studies on the respiratory metabolism of isolated human adipose cells

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Abstract
Some metabolic characteristics of fat cells isolated from 50 patients were examined The respiratory activity of human fat cells was of the same order or magnitude as cells obtained from the rat, whether the comparison was based on the molar triglyceride content of cells or the N content of tissue. There was no ifference in the respiratory metabolism of fat cells isolated from 3 separate age groups: 20-40, 40-60 and 60-80 yr. The respiratory activity of human adipose cells was partially inhibited by malonate (0.1 [image]), arsenite (1 m[image]) and iodoacetate (1 m[image]). Oxygen consumption by human adipose cells could not be stimulate? by adding glucose or glucose plus palmitic acid to the medium. However, stimulation of O2 uptake with these substrates was observed after the tissue had been preincubated for 5 hr. in a bicarbonate buffer. After the tissue had been preincubated for 5 hr., there was a linear relationship between the O2 uptake by isolated cells and the amount of oleic acid added to the incubation medium. Stimulation of O2 uptake by oleic acid (0.95 [mu]mole/ml) was dependent on the presence of glucose (5.6 m[image]) in the incubation medium. Of the total [1-C14]palmitic acid metabolized by human adipose cells, over 99.8% of the radioactivity was recovered in the neutral-lipid fraction and less than 0.2% in CO2. Under conditions where O2 uptake is stimulated by [C14]-palmitic acid, the radioactivity of the 1,2-diglyceride pool increased 20-fold.