BLOOD-PRESSURE RESPONSE TO MODERATE SODIUM RESTRICTION AND TO POTASSIUM SUPPLEMENTATION IN MILD ESSENTIAL-HYPERTENSION

To determine whether moderate restriction of dietary Na content or supplementation of K intake reduces blood-pressure in patients with mild essential hypertension, 12 patients were put on 3 different diets, a control diet (180 mmol Na/day), a Na restricted diet (80 mmol/day) and a K supplemented diet (200 mmol K/day). Each diet was taken for at least 4 wk and the sequence of the regimens was randomized. At the completion of each regimen intraarterial pressure was recorded continuously, and vasoactive hormones were measured hourly, for 24 h, under standardized conditions, in the hospital. Compared with the control diet, Na restriction was associated with lower blood-pressure readings in 7 patients, higher levels in 5 and an overall reduction in mean pressures of only 4.0/3.0 mm Hg (not significant). Individual differences in blood-pressure between these 2 diets correlated closely with concomitant differences in plasma renin activity (r = 0.75). K supplementation also resulted in variable changes in variable changes in arterial pressure, and the mean difference in pressure recordings (0.1/0.8 mm Hg) was insignificant. Moderate restriction of Na intake or supplementation of dietary K has variable effects on arterial pressure in individuals with mild essential hypertension and that overall the blood-pressure changes induced are very small. Responsiveness of the renin-angiotensin system may limit the fall in blood-pressure induced by Na restriction.