Freezing point depression of rat kidney slices during water diuresis and antidiuresis

¹ Laboratory of Kidney and Electrolyte Metabolism, National Heart Institute, National Institutes of Health, Bethesda, Maryland

The freezing point depression of slices of rat kidney removed during water diuresis or antidiuresis has been investigated with a microcryoscopic method. The osmotic pressure gradient in the inner medulla first demonstrated by Wirz has been confirmed. The inner medulla was found to be hypertonic to plasma during water diuresis. Hypotonic tubules were present throughout the cortex and outer stripe of the outer medulla.