Analyses of renal medullary lipid droplets from normal, hydronephrotic, and indomethacin treated rabbits

Lipid droplets isolated from rabbit renal medullary tissue were analyzed and found to be composed of triglyceride and free fatty acids in a ratio of 2.9:1. These triglycerides were unique when compared to triglycerides of other rabbit tissues examined, in that they contained high percentages of octadecanoic acid (stearic acid, 9.8%), 5,8,11,14-eicosatetraenoic acid (arachidonic acid, 6.8%), and 7,10,13,16-docosatetraenoic acid (adrenic acid, 10%). Lipid droplet triglycerides were found to increase during experimental hydronephrosis and after administration of indomethacin, a prostaglandin synthetase and phosphodiesterase inhibitor. From gas liquid chromatography of fatty acid methyl esters of these triglycerides, it was determined that they were enriched further in their percent composition of 9,12-octadecadienoic acid (linoleic acid) and arachidonic acid, a prostaglandin precursor. The inverse relationship between lipid droplets and prostaglandin content in the inner medulla suggested a significant role of lipid droplet triglycerides as storage pools for prostaglandin precursors.