Acute Effects of Sodium Chloride or Its Substitute Potassium Chloride on Vascular Function in Healthy Volunteers

Objective: High blood pressure, one of the most important risk factors for cardiovascular mortality, leads to vascular dysfunction and subsequently to arteriosclerosis, stroke, kidney and heart failure. High salt intake and low potassium intake are associated with high blood pressure and an increased risk of cardiovascular disease and mortality. Partial replacement of sodium with potassium led to a lower risk of cardiovascular events and death in a long-term follow-up study. However, the exact mechanism remains unclear. Our aim was to investigate the acute effects of sodium or potassium intake on vascular health to unravel the underlying mechanisms leading to vascular adaptations. Design and method: Six male and nine female healthy individuals (mean age 31 years) were randomized to either 9g of sodium chloride (high salt group), 6g of sodium chloride (regular salt group) or 6 g of sodium chloride plus 3g of potassium chloride group (substitution group). Individuals received a salty soup with the corresponding sodium or potassium load. Blood analyses, blood pressure, body composition and macro- as well as microvascular measurements were performed before as well as four (t4) and 24 hours (t24) after soup intake. To investigate macrovascular health, carotid-to-femoral pulse wave velocity was analyzed. Microvascular health was measured by investigating retinal vessel diameters. Results: The high (139±2mmol/l vs. 143±2mmol/l p=0,003) and regular salt group (140±2mmol/l vs. 141±0,6 mmol/l p=0,029) showed both higher serum sodium concentrations at t4 compared to baseline. These higher values were normalized at t24. The serum sodium concentration of the substitution group showed no statistically significant difference between timepoints. The substitution group showed improved microvascular health, quantified by higher arteriolar-to-venular diameter ratio from baseline to t4 (0,86±0,09 vs. 0,89±0,08 p=0,005). These improvements were regressive at t24 (0,88±0,09). No statistically significant changes were found on pulse wave velocity. The high and regular salt group showed no statistically significant differences at any timepoint on micro- or macrovascular health parameters. Conclusions: Replacement of sodium by potassium seems to improve microvascular function directly after potassium intake. These results might explain the long-term beneficial effects of potassium on cardiovascular outcomes.