Alterations by clofibric acid of glycerolipid metabolism in rat-kidney.

Alterations induced by p-chlorophenoxyisobutyric acid (clofibric acid) in glycerolipid metabolism in rat-kidney were studied. (1) The treatment of rats with clofibric acid markedly decreased renal level of triacylglycerol, which seemed to be due to a reduced formation of triacylglycerol, since the in vivo incorporation of [14C]oleic acid (18:1), [14C]linoleic acid (18:2) and [3H]glycerol into triacylglycerol was decreased in clofibric acid-fed rats. (2) The administration of clofibric acid to rats increased proportions of 18:1 and 18:2 and decreased a proportion of arachidonic acid (20:4) in phosphatidylcholine; the contents of two major molecular species of renal diacylglycerophosphocholine (diacyl-GPC), palmitoyl-arachidonoyl (16:0-20:4) and stearoylarachidonoyl (18:0-20:4), were both decreased markedly. The treatment did not alter renal content of phosphatidylcholine. (3) By contrast, clofibric acid changed, to a lesser extent, the composition of molecular species of diacylphosphatidylethanolamine. (4) The decrease in the level of diacyl-GPC that contains 20:4 seemed to be due to the clofibric acid-caused reduction in the concentration of free 20:4 in kidney. The reduction in renal concentration of free 20:4 seemed to be caused by a decrease in serum concentration of lipids that contain 20:4, but not by a decrease in the activities of desaturation and chain elongation that participate in biosynthesis of 20:4. (5) The reduction by clofibric acid in the renal content of diacyl-GPC containing 20:4 resulted in the decrease in the formation of prostaglandin E2 in kidney.