Short- and long-term neuroadrenergic effects of moderate dietary sodium restriction in essential hypertension.
Study Goal
The researchers aimed to assess the long-term neuroadrenergic and reflex effects of moderate sodium restriction in hypertensive patients.
Results Summary
Moderate sodium restriction triggered sympathetic activation and baroreflex impairment, which persisted over 8 weeks but reversed upon returning to a regular sodium diet. Blood pressure slightly decreased, while plasma renin activity, aldosterone, and MSNA significantly increased.
Population
11 untreated mild to moderate essential hypertensive patients (average age 42.0±2.6 years).
Effective Dosage
80 mmol NaCl per day.
Duration
8 weeks.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
moderate dietary sodium restriction | increase | sympathetic activation | untreated mild to moderate essential hypertensive patients | - | triggers | #1 |
moderate dietary sodium restriction | decrease | baroreflex impairment | untreated mild to moderate essential hypertensive patients | - | triggers | #2 |
low-sodium diet (80 mmol NaCl/d) for 1 week | decrease | urinary sodium excretion | untreated mild to moderate essential hypertensive patients | - | markedly reduced | #3 |
low-sodium diet (80 mmol NaCl/d) for 1 week | decrease | blood pressure | untreated mild to moderate essential hypertensive patients | - | slight reduction | #4 |
low-sodium diet (80 mmol NaCl/d) for 1 week | no change | heart rate | untreated mild to moderate essential hypertensive patients | - | no change | #5 |
low-sodium diet (80 mmol NaCl/d) for 1 week | increase | plasma renin activity | untreated mild to moderate essential hypertensive patients | - | significant increase | #6 |
low-sodium diet (80 mmol NaCl/d) for 1 week | increase | aldosterone | untreated mild to moderate essential hypertensive patients | - | significant increase | #7 |
low-sodium diet (80 mmol NaCl/d) for 1 week | increase | MSNA | untreated mild to moderate essential hypertensive patients | +23.0+/-4.6% | significant increase | #8 |
low-sodium diet (80 mmol NaCl/d) for 1 week | no change | baroreflex heart-rate control | untreated mild to moderate essential hypertensive patients | - | unchanged | #9 |
low-sodium diet (80 mmol NaCl/d) for 1 week | decrease | baroreflex modulation of MSNA | untreated mild to moderate essential hypertensive patients | 46.8+/-5.1% | reduced | #10 |
low-sodium diet (80 mmol NaCl/d) for 8 weeks | neutral | neurohumoral and baroreflex responses | untreated mild to moderate essential hypertensive patients | - | similar to the ones observed after 1 week | #11 |
restoration of regular sodium diet | neutral | all changes | untreated mild to moderate essential hypertensive patients | - | disappeared | #12 |
BACKGROUND: In essential hypertension, marked restrictions in dietary sodium intake cause in the short-term period an increase in muscle sympathetic nerve traffic (MSNA) and a baroreflex impairment. The present study was set out to assess on a long-term basis the neuroadrenergic and reflex effects of moderate sodium restriction. METHODS AND RESULTS: In 11 untreated mild to moderate essential hypertensive patients (age 42.0+/-2.6 years, mean+/-SEM), we measured beat-to-beat blood pressure (Finapres), heart rate (ECG), and MSNA (microneurography) at rest and during stepwise intravenous infusions of phenylephrine and nitroprusside. Measurements were performed at regular sodium intake, after 1 and 8 weeks of low-sodium diet (80 mmol NaCl/d), and repeated again at regular sodium intake. After 1 week, urinary sodium excretion was markedly reduced. This was accompanied by a slight blood pressure reduction, no heart rate change, and a significant increase in plasma renin activity, aldosterone, and MSNA (+23.0+/-4.6% P<0.05). Whereas baroreflex heart-rate control was unchanged, baroreflex modulation of MSNA was reduced by 46.8+/-5.1% (P<0.01). At the end of the 8-week low-sodium diet, the neurohumoral and baroreflex responses were similar to the ones observed after 1 week of the dietary intervention. All changes disappeared when regular sodium diet was restored. CONCLUSIONS: Thus, a moderate dietary sodium restriction triggers a sympathetic activation and a baroreflex impairment. Maintenance of low-sodium diet for several weeks does not attenuate these adverse adrenergic and reflex effects.