AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 4 896-R900, Copyright © 1989 by American Physiological Society
Release of atrial natriuretic factor during infusion of isoproterenol and angiotensin II
G. Christensen, A. Ilebekk and F. Kiil
Institute for Experimental Medical Research, University of Oslo, Ulleval Hospital, Norway.
Release of atrial natriuretic factor (ANF) is related to atrial pressure
and heart rate and may be influenced by beta-adrenergic stimulation and
angiotensin II. Experiments in five closed-chest dogs showed lower plasma
immunoreactive (ir) ANF during intravenous (iv) isoproterenol (0.2-0.3
micrograms.kg-1.min-1) and higher plasma ir-ANF during iv angiotensin II
(0.2-0.3 micrograms.kg-1.min-1) than during blood volume expansion measured
at equal mean right atrial pressure (RAP) and heart rate. This indicated
that the agents may affect ANF release differently, possibly through their
effects on left atrial pressure (LAP). In five open-chest dogs with right
atrial pacing at 216 +/- 1 beats/min, blood volume was expanded until mean
RAP was 9 mmHg. Mean LAP rose to 16.8 +/- 2.0 mmHg, and plasma ir-ANF rose
from 57 +/- 6 to 219 +/- 39 pg/ml. At a constant mean RAP of 9 mmHg, iv
isoproterenol infusion reduced mean LAP to 12.6 +/- 1.4 mmHg and reduced
plasma ir-ANF by 115 +/- 31 to 105 +/- 13 pg/ml. During iv angiotensin II
infusion at a mean RAP of 9 mmHg, mean LAP rose to 23.2 +/- 2.2 mmHg and
plasma ir-ANF averaged 281 +/- 77 pg/ml. The correlation between plasma
ir-ANF and LAP (r = 0.83) indicates that the different effects of
isoproterenol and angiotensin II on ANF release can be accounted for by the
effects on LAP.
