Urinary prostaglandins E2 and F2 alpha in chronic renal failure. Influence of chronic and acute changes in Na balance.

The role played by renal prostaglandins E2 (PGE2) and F2 alpha (PGF 2 alpha) in the modification of sodium homeostasis in chronic renal failure (CFR) was studied. The 24-hour urinary excretion of PGE2 and PGF2 alpha was measured before and after 5 days of a diet containing less than 20 mmol/day of sodium in 6 patients with CRF. At the end of this period, an acute sodium load (77 mmol/h of NaCl for 4 h) was administered and prostaglandins measured in hourly urine collections. In contrast to the findings previously reported in normal subjects, PGE2 and PGF2 alpha decreased with the low-sodium diet. The ratio PGE2/PGF2 alpha (reflecting the activity of the enzyme PGE2-9-ketoreductase) was greatly increased and did not change with the low-sodium diet. The acute sodium load induced an increase in urinary prostaglandins. The results suggest that prostaglandins may contribute to natriuresis in CRF, under basal conditions, after a short-term sodium depletion and in response to an acute sodium load. The changes in prostaglandin excretion in CRF could be related to decreased activity of PGE2-9-ketoreductase.