Prostaglandin E release in the dog: effect of sodium

Renal arterial injections (20 ml) of 4 M NaCl in 8 dogs and of 0.5 M NaCl in two dogs were followed by significant but delayed increases over 60 min in renal venous prostaglandin E (PGE) concentrations as measured by radioimmunoassay. Perfusion pressure increased significantly only at 5 min but plasma sodium concentration remained above base line for 60 min. In two dogs in which renal artery blood flow was maintained at a constant rate, comparable increases in PGE concentrations were observed. Injections of 1 M mannitol in three dogs and 5% dextrose in water in two dogs did not result in significant changes in PGE concentrations. In four dogs, administration of 50 mg indomethacin 15 min prior to injection of 20 ml of 4 M NaCl abolished the changes of PGE concentration. Sodium appears to have an effect on stimulation of PGE release by the canine kidney. This phenomenon may be of physiologic significance.