Intracytoplasmic granules of the inner medulla and papilla of the potassium depleted human kidney.

Morphological changes were studied in the kidney of a potassium depleted 21-year old Japanese male with Bartter's syndrome. Characteristic features were PAS-positive intracytoplasmic granules in the inner medulla and the papilla. The intracytoplasmic granules were conspicuous towards the papillary tip and ultrastructurally composed of small vesicles, vacuoles, amorphous dense materials, lamellar contents and myelin like figures, and bounded by a single limiting membrane. The granules in this human kidney were, with regard to their distribution and ultrastructural findings, similar to those in the kidney of experimentally potassium depleted rats. The results indicate that the intracytoplasmic granules in the renal inner medulla and the papilla are the characteristic feature of the potassium depleted human kidney and a counterpart to those in the potassium depleted rat.