Abstract
High dietary sodium intake can lead to hypertension and increased incidence of cardiovascular disease. We sought to determine the effect of short-term dietary sodium loading on central blood pressure and arterial stiffness in young (YG; 22-40 years) and middle-aged (MA; 41-60 years) normotensive adults. YG (n = 49; age: 27 ± 1 years) and MA (n = 36; age: 52 ± 1 years) subjects were randomized, in a cross-over design, to 7 days of low-sodium (LS; 20 mmol/d) or high-sodium (HS; 300 mmol/d) diet. On the last day of each diet, central pressures, forward and reflected wave amplitudes (via radial artery applanation tonometry), and carotid-femoral pulse wave velocity were assessed. Central systolic blood pressure (cSBP) was greater after HS in both YG (LS: 96 ± 1 vs. HS: 99 ± 1 mm Hg; P = .012) and MA (LS: 106 ± 2 vs. HS: 115 ± 3 mm Hg; P < .001). However, the increase in cSBP was greater in MA (YG: 4 ± 1 vs. MA: 9 ± 2; P = .02). In MA subjects, HS elicited greater forward (LS: 25 ± 1 vs. HS: 29 ± 1 mm Hg; P < .001) and reflected (LS: 19 ± 1 vs. HS: 23 ± 1 mm Hg; P < .001) wave amplitudes. Carotid-femoral pulse wave velocity was also greater in MA on HS but after adjustment for mean arterial pressure, the difference was no longer significant. Our data indicate that HS intake leads to a greater increase in cSBP in MA adults, which may be the result of increased forward and reflected wave amplitudes.