Isolation of hepatocellular lipid droplets: the separation of distinct subpopulations.

A new method for the isolation of lipid droplets from rat liver has been devised. The procedure involves tissue homogenization and discontinuous density gradient centrifugation. Six discrete bands of lipid particles, rich in triglyceride and cholesterol, are visible following 30 min of centrifugation at 25,770 g (max) in a swinging bucket rotor. An entire rat liver can be processed in 1-2 hr. Differences in the density of these liver lipid particles correlate with their triglyceride, sterol, phospho-lipid, and protein contents. The separation of these distinct populations of intracellular particulate neutral lipids provides an approach to the study of their origin and metabolism. This procedure may also be useful in the isolation of various populations of lipid-rich particles from other tissues.