Acute increase in right atrial pressure by intracardiac stimulation releases atrial natriuretic peptide

We studied the effect of an increase in heart rate and/or inright atrial pressure (RAP) on the release of at rial natriureticpeptide (ANP) in 18 patients. In group 1 (n = 6), right ventricularstimulation (100, 120, 140 and 150 bpm) was used to increaseRA P by asynchronous contraction of the right atrium and ventricle.Mean RA P increased from 3.9 ±0.2 to 8.3±0–6mmHg(mean±SEM). Median ANP levels increased from 120 to 440pgml^–1(P<0.05). In group 2 (n = 6), right atrial stimulation below140 bpm did not have any effect on ANP or RAP, but at a rateabove 140 bpm RAP increased from 5.8 ± 0.5 to 7.5 ±0.5mmHg and ANP from 226 to 396 pg ml^–1 (P < 0.05). Ingroup 3 (n - 6), RA P or ANP were not influenced by continuousright atrial stimulation at 110 bpm. Plasma cyclic GMP levelsparalleled the changes in plasma ANP. Thus, an acute incrementof RAP results in a release of ANP, but acceleration of heartrate alone has no effect on ANP secretion.