Increased Salt Appetite in Adrenalectomized Rats

Adrenalectomized rats are known to have a defmitely increased salt need, inasmuch as the administration of large quantities of salt either greatly reduces or eliminates the symptoms of insufficiency, and actually increases the survival incidence But is this need accompanied by an increased salt appetite, and will the adrenalectomized rat, if given free access to salt take sufficient quantity to keep itself alive and free from symptoms of insufficiency. 3 In an effort to answer these questions the following experiments were undertaken. METHODS. It was necessary for this purpose to devise a method by which salt could be given freely, under circumstances which made possible measurement of the actual amount ingested, It would have been simplest , of course, to present granular salt in a separate container. However , the small amount ingested daily and the comparatively large amount spilled or carried away on the paws definitely ruled out a quantitative measure by this method. For this reason salt was offered in solution in the drinking water. At the outset a 1 per cent salt solution was used because Rubin and Krick obtained their successful results from a solution of approximately this strength; but since, with only the salt solution available, the rat's intake would depend partly on the salt need and partly on the thirst for water, access was given at the same time to tap water presented in a second container. In this way the rat could satisfy its thirst and its salt appetite independently. In the first series of experiments with the 1 per cent salt solution and water, the animals also received the usual amount of salt in the McCallum diet (approximately 0.145 gm. per day). Inasmuch as the normal rats did not distinguish between the salt solution and the water, a second series of experiments was started with the strength of the salt solution increased to 3 per cent and no salt given in the food. It was found then that the normal animals did differentiate very definitely between the 3 per cent salt solution and the water. The rats were kept in individual cages containing a food cup, and two inverted graduated bottles, one with salt solution, the other with tap 155