1. Isolated rat kidneys were perfused with a modified Krebs-Henseleit medium at constant pressure.
2. When prostaglandin F2α (PGF2α) was infused into these kidneys at 0.1 μmol/l (final concentration) PGF2α-derived prostaglandin E2 (PGE2) could be identified by high-performance liquid chromatography and combined gas chromatography-mass spectrometry.
3. The extent of this conversion of PGF2α into PGE2 during passage through the kidney is dependent on the salt history of the rats from which the kidneys were taken for perfusion: kidneys from rats kept on normal diet converted 10%, those from rats on a low sodium diet 5% and those from rats kept on a high sodium diet 11%.
4. These differences in conversion can account for the different increases in renin release after PGF2α infusion in these groups.