CHANGES IN RENAL CONCENTRATING ABILITY PRODUCED BY PARATHYROID EXTRACT*

Abstract

The effects of parathyroid extract upon renal function and structure were studied in dogs. After 24 hr of hypercalcemia induced by parathyroid extract, GFR was usually but not always decreased. Renal concentrating capacity, as measured by the maximum solute concentration of urine during dehydration and by TcH2O during mannitol diuresis, was severely impaired. Dogs treated with parathyroid extract excreted a hypotonic urine during moderate mannitol diuresis despite the infusion of large amounts of exogenous vasopressin. These changes were associated with morphological alterations demonstrated by microdis-section to lie chiefly in the distal portion of the nephron and the collecting ducts.