Stimulation by volume expansion of atrial natriuretic peptide release from perfused rat heart

The release of immunoreactive (ir-) rat atrial natriuretic peptide (rANP) with volume expansion in in situ retrograde perfused rat heart was examined. The volume expansion induced by the infusion of the perfusion medium into the right atrium increased the mean right atrial pressure and the ir-rANP release without changing the rate of the heart beat. There was a significant correlation between the peak values of ir-rANP release and those of mean atrial pressure. The bilateral cervical vagotomy did not effect the ir-rANP release induced by the volume expansion. Therefore, it is highly likely that the stimulatory effect of volume expansion on rANP release is due to, at least in part, the atrial distension accompanied by an increase in mean atrial pressure, not involving a vagal system.