EFFECTS OF CENTRALLY ADMINISTERED ANGIOTENSIN ON SYMPATHETIC-NERVE ACTIVITY AND BLOOD-FLOW TO THE KIDNEY IN CONSCIOUS RATS

The effects of intracerebroventricular (i.c.v.) administration of different doses (10 pg-100 ng) of angiotensin II (AII) on renal sympathetic nerve activity (RSNA), mean arterial blood pressure (MAP), heart rate (HR), renal blood flow and femoral blood flow have been examined in conscious rats. Administration of All (10 ng) through a chronically implanted cannula induced an increase in MAP (20-22 mmHg), a decrease in HR (24 bpm), a decrease in RSNA by 57%, a decrease of femoral blood flow by 21% but no change in renal blood flow. The effects on MAP, HR and RSNA are greatly attenuated by the prior i.c.v. injection of an All-antagonist saralasin. In anesthetized rats. renal denervation significantly attenuated an increase in urinary sodium excretion induced by i.c.v. injection of AII. Since activation of the renal nerve is known to induce sodium reabsorption from the renal tubule and renin release, the relevance of the present finding is discussed in relation to the effect of AII on sodium excretion.