This study investigated the plasma concentrations of human atrial natriuretic peptide (hANP) of blood samples obtained from the aorta and coronary sinus (CS) in 19 male patients (mean age of 52.8 +/- 2.1 years) with ischemic heart disease before and during atrial pacing. The plasma concentrations of hANP were measured by radioimmunoassay, and the secretion rate of hANP was calculated on the basis of the CS-aorta difference in plasma hANP concentration and the CS flow rate recorded at blood sampling. Before atrial pacing, aortic plasma hANP concentration showed a significant positive correlation with mean pulmonary capillary wedge pressure (r = 0.67, p less than 0.002) or mean pulmonary artery pressure (r = 0.71, p less than 0.001), and a significant negative correlation with left ventricular ejection fraction (r = -0.50, p less than 0.05). During atrial pacing, aortic plasma hANP concentration increased from 67 +/- 13 (SEM) to 151 +/- 33 pg/ml (p less than 0.01), CS plasma hANP concentration from 727 +/- 121 to 1205 +/- 228 pg/ml (p less than 0.01), and the hANP secretion rate from 45.4 +/- 14.8 to 86.8 +/- 28.2 ng/min (p less than 0.05, n = 12). The aortic plasma hANP concentration was significantly correlated with the CS plasma hANP concentration (r = 0.81, p less than 0.001) or the hANP secretion rate (r = 0.70, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)