Atrial natriuretic hormone inhibits angiotensin II-stimulated sympathetic nerve activity in humans

We examined the effect of intravenous infusion of atrial natriuretic hormone (ANH) on the response of muscle sympathetic nerve activity (MSNA) to infused angiotensin II (ANG II) in humans. Infusion of saline alone or ANH (10 ng . kg(-1). min(-1)) alone produced no significant change in MSNA, whereas the infusion of ANG II (5 ng . kg(-1). min(-1)) alone caused a decrease in MSNA. Because elevations in arterial pressure (AP) and central venous pressure (CVP) also occurred due to ANG II, such elevations in AP and CVP could inhibit MSNA via baroreflexes. Then, the effect of ANG II on AP and CVP was inhibited by the simultaneous infusion of nitroprusside (N). Infusion of ANG II (5 ng . kg(-1). min(-1)) produced significant increases in MSNA when ANG II was infused along with N. However, the simultaneously infused ANH (10 ng . kg(-1). min(-1)) abolished the increases in MSNA induced by ANG II when the elevation in AP and CVP was inhibited by N. Thus ANH inhibits ANG II-induced sympathetic activation in humans. The results suggest that ANH may modulate sympathetic nerve activity at least in part by antagonizing the action of ANG II.