1. To evaluate in man by a non-invasive technique the possible role of prostaglandin (PG) compounds in initial renal haemodynamic effects after frusemide we studied the urinary excretion of PGE2 and of PGF2α before and at 15 min and 120 min after intravenous injection of this drug.
2. An increase of PGE2 and of PGF2α excretion was found in all 19 volunteer subjects within 15 min after frusemide, and PG excretion had returned towards control values at 120 min. The stimulation of PGF2α excretion by frusemide was markedly lower in men than in women, but this difference was statistically not significant.
3. No clear-cut relation was found between urinary PG compounds, on the one hand, and urinary volume, urinary sodium and urinary potassium, on the other hand, during the study.
4. The results support the assumption that the rapid increase of urinary PG compounds after frusemide, which parallels the changes in renal haemodynamics, may be an indicator of an activation of the PG system, in part or predominantly, in the vascular compartment.