Changes in human plasma atrial natriuretic polypeptide concentration in normal subjects during passive leg raising and whole-body tilting.

The effect of central venous pressure on release of human atrial natriuretic polypeptide (hANP) was studied by measuring the plasma hANP levels during passive leg raising to 60 degrees and head up whole-body tilt at 60 degrees in normal volunteers. In ten subjects, after at least 1 h recumbency, both legs were raised passively 60 degrees for 20 min. While the legs were raised the plasma hANP level increased significantly from a basal level of 101 +/- 10 pg/ml (mean +/- SE) to a peak of 165 +/- 15 pg/ml after 10 min, and returned to the basal level 10 min after the legs were lowered. The blood pressure and pulse rate were not affected by raising the legs. The effect of head up whole-body tilt of 60 degrees from the supine position, for 20 min, was examined in nine normal subjects. Their plasma hANP decreased transiently at 5 min in five of them and at 10 min or later in the remaining four subjects. Their blood pressure did not change but their pulse rate increased significantly while their body was being tilted. These results suggest that secretion of hANP is regulated physiologically by changes in the central venous pressure.