Dietary Sodium Restriction Rapidly Improves Large Elastic Artery Compliance in Older Adults With Systolic Hypertension

Abstract

We determined the temporal effects of dietary sodium restriction on large elastic artery compliance and systolic blood pressure (SBP) in 12 untreated, older (64±2 years) men and women (6 each) with stage 1 systolic hypertension. After baseline measurements subjects were assigned to 4 weeks of low or normal sodium intake (randomized, crossover design). Urinary sodium excretion was reduced by 60% by the end of week 1 of sodium restriction (54±11 mmol/d, P <0.01) versus baseline (135±14). Compared with baseline (0.11±0.01 mm/mm Hg), carotid artery compliance was increased by 27% (to 0.14±0.02, P <0.05) at the end of week 1 of sodium restriction, attaining peak levels by week 2 (+46%, to 0.16±0.02, P <0.01). Similarly, supine resting brachial artery SBP was reduced by >5 mm Hg by week 1 of sodium restriction, attaining peak reductions by week 2 (−12 mm Hg, P <0.01 versus baseline). The 24-hour ambulatory SBP was ≈3 mm Hg lower at week 1 of sodium restriction and ≈6 mm Hg lower by week 2 ( P <0.01 versus baseline). The reductions in resting SBP from baseline to week 2 of sodium restriction were strongly related to the corresponding increases in carotid compliance ( r =0.80, P <0.01). Urinary sodium excretion, carotid artery compliance, and SBP were not different during normal sodium intake versus baseline. Other subject characteristics were not different across conditions. Sodium restriction rapidly improves large elastic artery compliance in older adults with stage 1 systolic hypertension. These improvements in central arterial compliance appear to be a key mechanism in the rapid normalization of SBP by sodium restriction in these patients.