THE RELATIONSHIP BETWEEN SALT INTAKE AND THE POLYURIA OF EXPERIMENTAL DIABETES INSIPIDUS

Abstract

Cats with d. i. produced by interruption of the supraopticohyophyseal tracts showed a close parallelism between salt intake and urine vol. when the NaCl intake was on an abnormally high level, but this parallelism did not hold for salt intakes of normal or below normal levels. During fasting, the urine volume of a d. i. cat fell almost to the level characteristic of a normal animal. The loss of the polyuria was not due, however, to the salt deprivation which accompanied fasting, because if the salt intake was kept at a normal level during the fast by adding salt to the drinking water, the urine vol. fell just the same. Furthermore, the animal maintained his polyuria practically intact when placed on a diet almost completely free of salt. If there is any factor in the ordinary diet which causes the maintenance of the large fluid exchange of d. i., it is not the NaCl alone which is responsible; the claim which has been made for the hypophysectomized rat, that the polyuria is dependent on the salt in the ordinary diet, can not be valid for the d. i. cat.