THE EFFECT OF VASOPRESSIN (PITRESSIN) ADMINISTRATION ON SODIUM, POTASSIUM AND UREA EXCRETION IN RATS WITH AND WITHOUT DIABETES INSIPIDUS (DI), WITH A NOTE ON THE EXCRETION OF VASOPRESSIN IN THE DI RAT

Abstract

SUMMARY The effect of the administration of vasopressin as subcutaneous Pitressin Tannate in oil (PTO) was studied in the Brattleboro rat. Rats with hereditary hypothalamic diabetes insipidus (DI), and rats heterozygous for this abnormality, were used. A minimum dose of 1000 mu. of PTO/24 h was necessary to restore the urinary volume and osmolality of DI rats to values comparable with those of heterozygous rats. The urinary excretion of antidiuretic activity in DI rats was shown to be related to the dose of PTO. Sodium and urea excretion, but not potassium excretion, were reduced by up to 50% in the DI rat. No comparable changes were produced in the heterozygous rat. The possible mechanisms of these actions of vasopressin are discussed.