Dietary Sodium Loading Increases Central Systolic Blood Pressure More in Middle‐Aged Compared to Young Salt Resistant Adults

Abstract

Excess dietary sodium intake has been linked to increased incidence of cardiovascular disease and the development of hypertension. We sought to determine the effect of short‐term dietary sodium loading on central blood pressure in young (YG; n=46, 26±1 yrs) and middle‐aged (MA; n=27, 51±1 yrs) normotensive, salt resistant adults. Subjects were randomized to 7 days of low sodium (LS: 20 mmol/d) and 7 days of high sodium (HS: 300 mmol/d). Salt‐resistance was defined as mean 24‐hour MAP change 蠄5 mmHg between diets (LS: 87±1 vs. HS: 86±1 mmHg, p > 0.05). On the last day of each diet, carotid‐femoral pulse wave velocity (PWV) and the synthesis of a central aortic pressure waveform (by radial artery applanation tonometry and generalized transfer function) and wave separation analysis were performed. When compared to the LS diet, the HS diet elicited an increase in central systolic blood pressure (cSBP) in both YG (LS: 95±1 vs. HS: 98±1 mmHg, p < 0.05) and MA (LS: 107±2 vs. HS: 116±3 mmHg, p < 0.05), with a larger increase seen in MA (YG: 3±1 vs. MA: 9±2, p < 0.05). In MA, HS elicited greater central forward wave amplitude (LS: 26±1 vs. HS: 30±1 mmHg, p < 0.05) and central reflected wave amplitude (LS: 18±1 vs. HS: 22±1 mmHg, p < 0.05) but no difference was seen in YG. PWV was not altered by 7 days of HS in either group (p>0.05). These data suggest that higher sodium intake is associated with a greater increase in cSBP in MA compared to YG adults that may be due to increases in forward and reflected wave amplitudes.Supported by NIH Grant R01 HL104106