The relationship of urinary prostaglandins and plasma renin to sodium balance and diuresis in normal man.

The significance of changes in sodium balance and urinary sodium excretion for renal PG excretion was studied in normal man. In protocol B a strongly negative sodium balance was produced in 5 healthy young subjects by a low sodium diet given for 7 days (lo mmol Na/day) with 80 mg furosemide p.o. added on the last two days. 24 hour urinary PGE2 excretion remained constant, while plasma renin increased. In protocol A the effect of i.v. furosemide (1 mg/kg bwt) on urinary PGE2 and PGF2 alpha excretion rates was examined in 5 healthy young subjects. Rapid but short-lasting increases in PG excretion rates ran in parallel with the changes in urine flow rate. The study suggests that PGE2 is not of importance for the sodium homeostasis in normal man. Renal prostaglandins may play a modifying role for the renal response to loop diuretics but are hardly instrumental for the diuretic effect.