| Autor: |
Babcock MC; From the Department of Kinesiology and Applied Physiology, University of Delaware, Newark (M.C.B., A.T.R., K.U.M., J.C.W., M.M.W., W.B.F.)., Robinson AT; From the Department of Kinesiology and Applied Physiology, University of Delaware, Newark (M.C.B., A.T.R., K.U.M., J.C.W., M.M.W., W.B.F.)., Migdal KU; From the Department of Kinesiology and Applied Physiology, University of Delaware, Newark (M.C.B., A.T.R., K.U.M., J.C.W., M.M.W., W.B.F.)., Watso JC; From the Department of Kinesiology and Applied Physiology, University of Delaware, Newark (M.C.B., A.T.R., K.U.M., J.C.W., M.M.W., W.B.F.)., Wenner MM; From the Department of Kinesiology and Applied Physiology, University of Delaware, Newark (M.C.B., A.T.R., K.U.M., J.C.W., M.M.W., W.B.F.)., Stocker SD; Division of Renal-Electrolyte, Department of Medicine, University of Pittsburgh, PA (S.D.S.)., Farquhar WB; From the Department of Kinesiology and Applied Physiology, University of Delaware, Newark (M.C.B., A.T.R., K.U.M., J.C.W., M.M.W., W.B.F.). |
| Abstrakt: |
The American Heart Association recommends no more than 1500 mg of sodium/day as ideal. Some cohort studies suggest low-sodium intake is associated with increased cardiovascular mortality. Extremely low-sodium diets (≤500 mg/d) elicit activation of the renin-angiotensin-aldosterone system and stimulate sympathetic outflow. The effects of an American Heart Association-recommended diet on sympathetic regulation of the vasculature are unclear. Therefore, we assessed whether a 1000 mg/d diet alters sympathetic outflow and sympathetic vascular transduction compared with the more commonly recommended 2300 mg/d. We hypothesized that sodium reduction from 2300 to 1000 mg/d would not affect resting sympathetic outflow but would reduce sympathetic transduction in healthy young adults. Seventeen participants (age: 26±2 years, 9F/8M) completed 10-day 2300 and 1000 mg/d sodium diets in this randomized controlled feeding study (crossover). We measured resting renin activity, angiotensin II, aldosterone, blood pressure, muscle sympathetic nerve activity, and norepinephrine. We quantified beat-by-beat changes in mean arterial pressure and leg vascular conductance (femoral artery ultrasound) following spontaneous sympathetic bursts to assess sympathetic vascular transduction. Reducing sodium to 1000 mg/d increased renin activity, angiotensin II, and aldosterone ( P<0.01 for all) but did not alter mean arterial pressure (78±2 versus 77±2 mm Hg, P=0.56), muscle sympathetic nerve activity (13.9±1.3 versus 13.9±0.8 bursts/min, P=0.98), or plasma/urine norepinephrine. Sympathetic vascular transduction decreased ( P<0.01). These data suggest that reducing sodium from 2300 to 1000 mg/d stimulates the renin-angiotensin-aldosterone system, does not increase resting basal sympathetic outflow, and reduces sympathetic vascular transduction in normotensive adults. |
