Effects of repeated increments in right atrial pressure on secretion of atrial natriuretic factor.

I t has been demonstrated that an acute increase in right atria1 (RA) pressure and paroxysmal supraventricular tachycardias induce the release of atria1 natriuretic factor (ANF).*-4 In a previous study that allowed a selective or combined increase in heart rate and RA pressure by intracardiac pacing, we showed that acute increment in RA pressure is the determinant factor for ANF secretion.5 Hollister et al3 demonstrated that, in subjects with elevated ANF levels due to a high salt diet, ANF release caused by atria1 pressure increment was higher compared with subjects with normal baseline ANF. These data suggest that under chronically stimulated ANF secretion, there might be a higher sensitivity of ANF release to additional secretory stimuli. However, it is unknown whether there is an adaptation of the ANF release to repetitive secretion stimuli. We therefore investigated the ANF response to repeated identical atria1 pressure increments.