Effects of infused norepinephrine and angiotensin-II on vasopressin levels in humans.

Angiotensin II (A-II) has been shown to stimulate plasma arginine vasopressin (AVP) secretion in experimental animals, although offsetting effects from a rise in arterial pressure may obscure the effect. A rise in plasma norepinephrine (NE) may have several effects on plasma AVP because of changes in arterial pressure and central adrenergic stimulation. As little data exist concerning these neurohumoral interrelationships in humans, the current investigation was performed to examine the role of acute changes in plasma NE and A-II in the control of arginine vasopressin (AVP). The question is of potential importance because of diffuse disturbances in neurohumoral control in diseases such as hypertension and congestive heart failure. We measured heart rate, arterial pressure, and plasma AVP during 2.5 and 5.0 micrograms/min infusions of NE, and during .05 and .10 micrograms/kg/min infusions of A-II. NE increased mean blood pressure from 81 +/- 11 mm Hg to 87 +/- 16 mm Hg at 2.5 micrograms/min and to 93 +/- 16 mm Hg at 5.0 micrograms/min (p less than .001). Heart rate was unchanged during the 2.5 micrograms/min infusion but declined from 58 +/- 9 beats/min to 54 +/- 9 beats/min during the 5.0 micrograms/min infusion (p = NS). Plasma AVP, 3.0 +/- 0.9 pg/mL, did not change. During A-II infusions, mean arterial pressure increased from 81 +/- 13 mm Hg to 92 +/- 17 mm Hg and 112 +/- 21 mm Hg at the two rates (p less than .001); heart rate declined from 61 +/- 6.8 beats/min to 59 +/- 9.1 beats/min and 56 +/- 11.3 beats/min (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)