Renal deficiency associated with diabetes insipidus in the SWR/J mouse.

The age-dependent polydipsia and polyuria observed in SWR/J mice was found to be caused by relative inability of the kidneys to respond to antidiuretic hormone (ADH), resulting in a concentrating defect, which persisted even following Pitressin injection or water deprivation. Posterior pituitaries contained large amounts of ADH, which was also found in the urine and increased in output following water deprivation, indicating normal, or above normal synthesis and release of ADH. Kidneys of polydipsic SWR/J mice weighed more than those of normal strains and sometimes contained a lesion in the medullary area. No clear relationship was found between the size of the lesion and water intake.