Abstract P206: Increased Short-term Dietary Sodium Intake Does Not Increase Blood Pressure or Measures of Aortic Stiffness in Young Healthy Adults

Abstract

Background: Sodium (Na) sensitivity is defined as the short-term increase in blood pressure (BP) after increased Na intake. The impact of Na sensitivity on measures of aortic stiffness has not been previously characterized in non-hypertensives. We tested the feasibility of an oral Na loading protocol to characterize the effects of increased dietary Na on blood pressure and measures of aortic stiffness in health young adults. Methods: In an open-label repeated measures pilot study, we enrolled 40 healthy adults age 21-30 years (18 females). Subjects were evaluated before and after 7 days of oral Na loading (12g (205 mmol) of salt tablets/day). BP (mmHg, cuff method) was measured in supine, seated and standing positions. Radial artery tonometry (Sphygmacor) was used to assess measures of aortic stiffness: aortic BP (mmHg), aortic pulse pressure (mmHg), aortic augmentation index (%) and adjusted Tr, time of return of the reflected pressure wave as an index of aortic pulse wave velocity (m/s). Serum aldosterone, urine Na and potassium (K) were measured. Results: Nine subjects dropped out due to GI intolerance of the salt pills. In the remaining 31 subjects, Na loading did not change BP in any position, aortic BP, aortic pulse pressure, or Tr (Table: mean±SD for seated R arm BP and measures of aortic stiffness). There was no measurable aortic augmentation in the cohort. Na loading decreased serum aldosterone (9.1±1.5 to 5.2±0.8 ng/dl, p=0.02), and increased urine Na:K ratio (1.8±0.2 to 3.5±0.5, p=0.002). Conclusion: Oral Na loading was associated with suppression of the renin-angiotensin aldosterone system, did not increase BP, or measures of aortic stiffness in healthy young adults.