RESULTS

Relationship between sodium andurea concen-trations in serum. It will be seen from Figure 1, that, in a dog maintained on moderate doses of cortical extract, a decrease in blood sodium and an increase in blood urea could be induced either by the withdrawal of salt from the diet, by the gradual reduction of the dosage of cortical extract or by its complete withdrawal, as has been observed by Harrop (2, 3). These changes in blood sodium and in blood urea, whether they followed the withdrawal of salt or the withdrawal of cortical extract, were accompanied by a progressive fallin the phthalein excretion and in urea clearance. However, the velocity and extent of these changes were greater subsequent to the withdrawal of cortical extract than to the withdrawal of salt. When an unusually potent preparation of extract was employed (Periods 30 to 33) reduction in the salt intake failed to influence the blood sodium, the blood urea or theurea clearance. As might