Urine Osmolarity and the Excretion of Prostaglandin E2 in Man

We have studied urine flow rates (ml/min), urine osmolarity (mosm/1), and the urinary concentration (pg/ml) and excretion rates (ng/2 h) of prostaglandin E2 (PGE2) in 2 healthy subjects after an oral water load (1,000 ml) and during subsequent fluid deprivation for 11 h. Both with and without inhibition of endogenous prostaglandin synthesis with indomethacin (150 mg/day for 3 days) a rise in the concentration of urinary PGE2 was seen during anti-diuresis in parallel with urinary osmolarity (without indomethacin: r = 0.85, p < O.001; during indomethacin: r = 0.91, p < O.001 ;fig. 1A) and in reciprocity with urine flow rate (without indomethacin: r = -0,73, p < O.Ol; during indomethacin: r = -0.68, p < 0.01; fig. IB). No correlation was seen between urine flow rate and the excretion of PGE2 during antidiuresis.