SALT AND WATER DISTRIBUTION IN HEREDITARY AND IN INDUCED HYPOTHALAMIC DIABETES INSIPIDUS IN THE RAT

Salt and water metabolism and the distribution of Na, K, and water in gastrocnemius and in aorta were measured in spontaneous hereditary hypothalamic and in surgically induced diabetes insipidus in the rat. The degree of severity in the two types of the disease was estimated in terms of salt and water handling. Water turnover in 24 hours was about equal to body weight in the hereditary disease and about 60% of body weight in the induced disease. Skeletal muscle Na increased more than 20% in the familial disease, and the gain involved both cells and environment. There was no corresponding loss of K. Similar changes of lesser degree were noted in the induced disease. The degree of Na accumulation appears to be partially dependent on the duration of the disease.