Weight reduction decreases atrial natriuretic factor and blood pressure in obese patients.

The relationship between atrial natriuretic factor (ANF), the renin-aldosterone axis, and blood pressure reduction with weight loss was investigated in 18 obese subjects (five hypertensive and 13 normotensive) placed on a 12-week, low-sodium (40 mmol), weight-reducing diet. ANF was significantly higher (P less than .02) in the obese hypertensive group compared with the obese normotensive group throughout the study. There was a dramatic fall in the circulating concentration of ANF after 1 week of weight reduction in both obese groups. Mean arterial pressure fell significantly in both groups, with the hypertensive group becoming normotensive during the first week of the diet. The marked changes in ANF and mean arterial pressure during the first week of the diet appeared related to reduced salt intake. Mean arterial pressure and ANF concentrations, however, continued to fall during the eighth to 12th week of weight reduction diet in the hypertensive patients when salt intake had been unchanged for several months. In both the hypertensive and normotensive subjects ANF paralleled blood pressure changes (r = .54, P less than .0001) throughout the 12-week study period. ANF was inversely correlated with plasma renin activity and aldosterone, with the most dramatic changes in their concentrations being during the first week of the diet. These results demonstrate that weight loss while ingesting a controlled low sodium diet is accompanied by changes in ANF that directly correlate with changes in blood pressure and inversely correlate with changes in the renin-aldosterone axis, which ANF is known to inhibit.