1. The mechanism by which pretreatment of rats with intracisternal 6-hydroxydopamine prevents the onset of deoxycorticosterone hypertension has been studied.
2. Rats pretreated with central 6-hydroxydopamine increase their consumption of 0.17 mol/l sodium chloride-0.03 mol/l potassium chloride (‘saline’) less than normal rats when implanted with deoxycorticosterone.
3. Intact rats restricted to the equivalent consumption of saline of rats pretreated with 6-hydroxydopamine develop hypertension despite this restriction.
4. It is suggested that the prevention of deoxycorticosterone hypertension by central 6-hydroxydopamine does not depend on reduced saline consumption.