Effects of active postural changes on plasma atrial natriuretic factor in normal healthy subjects

The effects of active changes in posture, from recumbency to upright position (60 minutes), on the circulating levels of atrial natriuretic peptide (ANP) in healthy human subjects were studied by using a radioimmunoassay method. In supine position, plasma ANP levels ranged from 12 pg/ml to 51.5 pg/ml, with an average level of 35.3 ± 11.5 pg/ml. After 1 hour of orthostatic position, plasma ANP levels varied from 10 pg/ml to 35 pg/ml, with an average level of 21 ± 11.5 pg/ml. These results suggest that ANP is involved in the haemodynamic modifications following postural stimuli. Thus, postural changes can be taken into account for evaluating plasma ANP behaviour properly.