EFFECT OF ANGIOTENSIN ON SYMPATHETIC NERVE ACTIVITY

The nervously mediated effect of angiotensin was studied in 13 rabbits by recording of renal and cervical sympathetic nerve activities, and was compared to results obtained with infusion of noradrenalin. I.v. infusion of angiotensin (0.5—3 μg/kg · min) raised the blood pressure, and initially reduced the normal rhythmical sympathetic activity. Whereas with noradrenalin the reduction of sympathetic nerve activity persisted, being determined by the blood pressure level, angiotensin shortly after the start of infusion was found to induce a non‐rhythmical activity in the renal nerve. This activity was associated with a further rise of blood pressure. The non‐rhythmical activity and the concomitant pressure rise were transient, and disappeared after a few minutes, in spite of continued infusion of angiotensin. This suggests that the nervously mediated effect, although capable of causing considerable transient increase of arterial blood pressure, is of minor importance for the blood pressure response to prolonged infusion of angiotensin in rabbits. The non‐rhythmical sympathetic activity was not related to changes in baroreceptor activity, and was probably not caused by stimulation of chemoreceptors or sympathetic ganglions. Most likely, this effect of angiotensin was brought about by interaction with central sympathetic neurons. © 1968 Scandinavian Physiological Society