The response of atrial natriuretic factor to an acute increase in atrial pressures produced by changing from a 45 degrees upright to a -15 degrees Trendelenburg tilt was examined in 21 patients with heart failure and 8 control subjects with normal hemodynamics. In the control subjects, baseline (45 degrees upright tilt) pulmonary capillary wedge and right atrial pressures increased from 3.1 +/- 0.9 (mean +/- SEM) and 4.4 +/- 0.3 mm Hg to 6.9 +/- 1.9 and 8.5 +/- 0.4 mm Hg, respectively (p less than 0.05 for both), 30 min after the -15 degrees tilt. Baseline arterial plasma atrial natriuretic factor concentration increased from 34 +/- 4 to 44 +/- 1 pg/ml (p less than 0.05) 30 min after the tilt, with an increase observed in every patient. In the group with heart failure, baseline pulmonary capillary wedge and right atrial pressures increased from 17.5 +/- 2.0 and 5.3 +/- 1.2 mm Hg to 24.6 +/- 1.8 and 9.7 +/- 1.3 mm Hg, respectively (p less than 0.01 for both), 30 min after the tilt. Plasma atrial natriuretic factor concentration was 326 +/- 38 pg/ml at baseline and 347 +/- 34 pg/ml (p = NS) 30 min after tilt. Compared with the 7 patients with heart failure who had increased atrial natriuretic factor concentrations after the tilt (responders), the 14 patients with unchanged or decreased atrial natriuretic factor concentrations after the tilt (nonresponders) had a higher baseline right atrial pressure and atrial natriuretic factor concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)