Abstract
A careful study was performed in two patients of idiopathic diabetes insipidus (DI) to assess the role of renal hemodynamic changes in antidiuresis induced by several agents commonly used for the treatment of DI patients.' In one patient, every one of chlorpropamide, clofibrate and thiazide caused a decrease in effective renal plasma flow (ERPF) by about 20% in association with a decrease in urine volume by 40-50%. No significant decrease in GFR was seen in the patient. In the other patient, every one of the above drugs caused a decrease not only in ERPF (by 25-40%) but also in GFR (by 25-35%) in association with a more remarkable decrease in urine volume (by 60-70%). These renal hemodynamic changes resembled those induced by the administration of exogenous vasopressin. Thus renal hemodynamic changes should be taken into consideration when one studies the mechanism of antidiuresis induced by the drugs mentioned above.
