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Sodium, large arteries and diuretic compounds in hypertension
Insights
Sodium intake and diuretic use impact arterial properties in hypertension. Low sodium intake and certain diuretics may improve arterial compliance and diameter, independent of blood pressure changes.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Pharmacology
Background:
- Antihypertensive drugs yield varied arterial compliance changes for similar blood pressure reduction.
- Limited data exist on sodium and diuretic effects on hypertensive arterial wall viscoelasticity.
Purpose of the Study:
- To review the effects of sodium intake and diuretics on arterial viscoelastic properties in hypertension.
- To explore sodium's independent impact on arterial wall characteristics.
Main Methods:
- Analysis of cross-sectional epidemiological and longitudinal studies.
- Review of animal studies and crossover trials involving hypertensive subjects.
- Examination of hemodynamic parameters like pulse wave velocity and brachial artery diameter.
Main Results:
- Low sodium intake correlates with lower pulse wave velocity and larger brachial artery diameter in hypertensive individuals.
- Sodium overload reduces arterial compliance and distensibility, independent of blood pressure.
- Some diuretics (cycletanine, indapamide) increased arterial compliance, while hydrochlorothiazide did not.
Conclusions:
- Sodium influences the arterial wall independently of blood pressure modifications.
- Counter-regulatory systems may explain differing effects of diuretic compounds.
Background:
Clinical and experimental data have shown that different antihypertensive drugs do not cause similar changes in arterial compliance for an equipotent blood pressure reduction. There are no clear data on the effects of sodium and diuretics on the visco-elastic properties of the hypertensive arterial wall.
Data Analysis:
Cross-sectional epidemiological studies suggest that for given values of age and blood pressure, pulse wave velocity is lower in the presence than in the absence of a low sodium intake. Longitudinal studies indicate that in hypertensive subjects, a low sodium intake is associated with a larger brachial artery diameter than that seen with a high sodium intake. In hypertension in the elderly and in severe hypertension with end-stage renal disease, a sodium overload reduces arterial compliance and distensibility independently of blood pressure changes. In animal studies, the diuretic compounds cycletanine and indapamide increase systemic and carotid compliance independently of blood pressure changes. In contrast, in a crossover study in hypertensive subjects, the diuretic agent hydrochlorothiazide did not change arterial compliance and pulse wave velocity while the calcium entry-blocker felodipine did improve these hemodynamic parameters.
Conclusion:
The studies reviewed indicate that sodium may act on the arterial wall independently of blood pressure changes. the contribution made by counter-regulatory mechanisms, which may be related to the renin-angiotensin and the sympathetic nervous systems, might explain the differences between the clinical and the experimental changes observed with diuretic compounds.