CHANGES IN ATRIAL-NATRIURETIC-PEPTIDE AND PLASMA-RENIN ACTIVITY FOLLOWING CHANGES IN RIGHT ATRIAL PRESSURE IN PATIENTS WITH CHRONIC-RENAL-FAILURE

Since it was first discovered in the early 1980s, the role of atrial n atriuretic peptide (ANP) in the control of fluid and electrolyte balan ce and blood pressure has been extensively studied in both health and disease. We report here a study of ANP and its relationship to corresp onding changes in right atrial pressure (RAP) in patients with chronic renal failure (CRF) on haemodialysis compared to healthy controls. Al though there was a positive correlation between RAP and ANP in both gr oups, the changes in ANP following changes in RAP between the two grou ps were not statistically significant. A unique observation was the re sponse of RAP to changes in posture, with RAP falling significantly as expected in healthy controls in contrast to the exceptional absence o f a significant fall in patients with CRF. Healthy controls demonstrat ed appropriate postural changes in plasma renin activity (PRA) despite marked suppression of PRA levels due to salt loading, in complete con trast to patients with CRF who, despite chronic fluid overload and ele vated levels of ANP, continued to have grossly elevated PRA levels tha t failed to change significantly in response to changes in posture.