Interaction of Amphotericin B and Vasopressin in the Rat Kidney and the Toad Urinary Bladder

Abstract

The interaction of amphotericin B (AmB) and vasopressin (ADH) was studied in the rat and the toad urinary bladder. In the anesthetized rat infused with a sustaining dose of ADH, AmB administration resulted in a decrease in urine osmolality and increases in urine flow and fractional water and Na excretions. However, the urine flow for a given osmolar clearance was higher after AmB than before, indicating that free water reabsorption is inhibited by AmB. Micropuncture experiments suggested an inhibition of proximal Na reabsorption after AmB. In the toad bladder, AmB added to the mucosal side enhanced osmotic water flux and impaired hydroosmotic action of ADH. These results indicate a functional antagonism between AmB and ADH in the renal tisssue.