The distribution of labeled palmitic acid into the diglycerides and triglycerides of rat adipose tissue.

After in vitro incubation of rat epididymal fat pads with radioactive palmitic acid, the distribution of the label in the different lipid classes and in different triglycerides was determined by silica gel and silver nitrate-silica gel thin-layer chromatography (TLC).The radioactivity of the diglycerides was approximately half of the triglycerides. This ratio did not change with alteration in the time of incubation. It remained unaltered even after a subsequent 10-min incubation in a nonradioactive medium.When the fat pads were incubated, first with(14)C-, then with(3)H-labeled palmitic acid, the(3)H/(14)C ratio was slightly lower in diglycerides than in triglycerides.The fully saturated molecules contained 38% of the radioactivity of triglycerides. Addition of oleic acid or norepinephrine to the labeled palmitic acid-containing medium decreased this value. Subsequent incubation with these compounds did not alter the distribution of radioactivity.