Excretion of 6-keto-PGF1 alpha and PGE2 in rats with hereditary hypothalamic diabetes insipidus.

We measured the urinary excretion of a stable metabolite of prostacyclin, 6-keto-PGF1 alpha, and of PGE2 in homozygous Brattleboro rats, a strain with hereditary hypothalamic diabetes insipidus. Excretion of both prostaglandins was largely increased compared to both heterozygous Brattleboro rats and Long-Evans rats. These results are in contrast to previously published observations demonstrating a subnormal excretion of PGE2 in Brattleboro rats. It is suggested that prostaglandin synthesis may be under tonic inhibitory control by vasopressin both in the kidney and in the endothelial cells of blood vessels. The findings further support the view that prostaglandins play an important role in the regulation of water excretion and in the pathogenesis of polyuric conditions.