ATRIAL-NATRIURETIC-FACTOR INHIBITS NORADRENALINE RELEASE IN THE PRESENCE OF ANGIOTENSIN-II AND ANGIOTENSIN-III IN THE RAT HYPOTHALAMUS

1. Atrial natriuretic factor effects on neuronal noradrenaline release evoked by angiotensin II or III and high potassium solution plus angi otensin II and III in the rat hypothalamus were studied. 2. Atrial nat riuretic factor (10 nM) did not modify spontaneous noradrenaline relea se. On the other hand, the atrial factor diminished the increase of no radrenaline release induced by both angiotensin II (1 muM) or angioten sin III (1 muM). 3. Ten nanomolar ANF reduced the amine output induced by 100 nM KCl. Both angiotensins enhanced the 3H-noradrenaline secret ion stimulated by high potassium solutions. When atrial natriuretic fa ctor was added to the medium containing the depolarizing KC] solution plus angiotensin II or III (1 muM), the diminishing effects were great er than when the atrial factor was added to the depolarizing solution alone. 4. Our results suggest that atrial natriuretic factor effects o n noradrenaline release, evoked by angiotensin II, III and KCI, may be involved in the regulation of the central catecholamine pathways and sympathetic activity.