Abstract

To study the effect of dietary modification on urinary prostaglandin E (UPGE) excretion and on renal fatty acid compositions, weanling male rats were raised on a fat-free diet for 6 weeks and were switched to a diet containing 2 energy % of linoleic acid (LA) for 8 days. During fat deprivation, UPGE excretion increased in the first week (6.9 ng/24 hours urine), fell to a minimum of 1.1 ng/24 hours at 3rd week and thereafter remained at a level lower than that in the controls (3.1 ng/24 hours). UPGE excretion returned rapidly to normal (2.7 ng/hr) only 24 hours after LA supplementation. During LA treatment, arachidonic acid (AA) concentrations in renal cholesteryl esters rapidly increased from 19% to 27% (33% in the controls), while concentrations in renal phospholipids (PL) and renal free fatty acids (FFA) did not change during the first four days but reached the normal range at the 8th day. The present studies demonstrate that chronically fat deficient animals excreted significantly less UPGE than that in the controls. However, this deficiency could be rapidly reversed by LA supplementation despite the fact that AA levels in renal lipid fractions remained well below normal. This suggests that dietary LA may be rapidly converted to AA and subsequently to PGE without AA levels rising in the lipid fractions usually thought of as being PG precursors.