In Cushing's syndrome, deoxycorticosterone acetate causes a saluresis instead of the expected sodium retention (Soffer, Lesnick, Sorkin, Sobotka & Jacobs, 1944). In sheep on a high salt intake aldosterone also can cause a saluresis instead of sodium retention (Burstyn, Horrobin & Manku, 1972). The more usual sodium-retaining action can be restored by treatment with prolactin. In sheep we have therefore tested whether cortisol treatment can cause aldosterone to have a sodium-losing action and whether this can be converted back to a sodium-retaining action by prolactin.
Six dioestrous Merino ewes were studied. They were prepared and treated throughout the experiment with a supplement of 80 mequiv. sodium chloride/day as previously described (Burstyn et al. 1972). Each day urine was collected from each animal for two successive 2-h periods from 12.00 to 14.00 and from 14.00 to 16.00 h. The urine volume and sodium and potassium concentrations (measured by means of a