AJP - Heart and Circulatory Physiology, Vol 253, Issue 5 1044-H1052, Copyright © 1987 by American Physiological Society
Release of atrial natriuretic factor from heart-lung preparations of inbred Dahl rats
M. O. Onwochei, R. M. Snajdar and J. P. Rapp
Department of Medicine, Medical College of Ohio, Toledo 43699.
Isolated heart-lung preparations from hypertensive inbred Dahl
salt-hypertension sensitive (S) and normotensive inbred Dahl
salt-hypertension resistant (R) rats were perfused using 15% washed rat red
blood cells in Krebs-Ringer bicarbonate buffer. Atrial pressures were
increased by increasing venous return (preload) or by increasing the
arterial resistance (afterload). Increases in preload at a constant
afterload produced increases in the right and left atrial pressures
equivalent between S and R strains. Atrial natriuretic factor (ANF) release
was linearly related to right atrial pressure (RAP) or left atrial pressure
(LAP) in either strain, but S released more ANF at each level of preload,
and the slope of the line relating ANF release to RAP was significantly
greater in S than R. When the heart-lung preparations were subjected to
changes in afterload at a constant preload, LAP was significantly increased
in R but not in S rats, and concomitantly ANF increased in R but not in S.
In the afterload experiments, as in the preload studies, S released more
ANF than R for comparable LAP. It is concluded that 1) at any atrial
pressure, hearts of hypertensive S rats release more ANF than hearts of
normotensive R rats, 2) this strain difference is probably a consequence of
hypertension, and 3) the observed relationships between ANF release and
atrial pressures support the contention that atrial distention stimulates
the release of ANF.
