Central Administration of Aldosterone Increases Blood Pressure in Rats

Experiments were designed to determine whether hypertension in rats caused by a central infusion of aldosterone requires supplemental sodium and uninephrectomy. Group 1 was uninephrectomized and received an intracerebroventricular (i.c.v.) infusion of aldosterone (9 ng/h) plus 1M NaCl, dissolved in 0.01% ethyl alcohol-artificial cerebrospinal fluid (vehicle). Group 2 received the same infusion but was not uninephrectomized. Group 3 received an i.c.v. infusion of aldosterone alone in vehicle. Group 4 received an i.c.v. infusion of vehicle with intravenous (i.v.) infusion of aldosterone plus NaCl. All rats received a diet of standard Purina rat chow and tap water ad libitum. Systolic blood pressure of groups 1 and 2 was significantly increased. Rats treated with i.c.v. aldosterone alone also showed a significant increase in blood pressure on day 21. However, i.v. infusion of the same dose of aldosterone did not change blood pressure. The results show that hypertension induced with chronic central infusion of aldosterone does not require uninephrectomy. We conclude that aldosterone may act directly within the central nervous system to increase blood pressure.