Sodium and large arteries in hypertension. Effects of indapamide

Epidemiologic studies evaluating arterial pulse wave velocity together with blood pressure indicate that: (1) salt intake has an independent effect on arteriolar tone and arterial wall properties, with the former indirectly and the latter directly contributing to increased arterial stiffness with age; and (2) normotensive adult subjects who follow a low sodium diet have reduced arterial stiffness and this effect is independent of blood pressure. Conversely, in elderly persons with isolated systolic hypertension, isotonic saline infusion causes a predominant increase in systolic pressure due to an increase in the stiffness of the arterial wall. The diuretic indapamide produces a decrease in blood pressure without significant change in brachial artery diameter. The result indicates a shift of the pressure-diameter curve, reflecting for the first time in humans a pharmacologic effect of the drug on arterial vessel. Furthermore, diuretic drugs may increase arterial distensibility and compliance in hypertensive patients, but this effect seems to be more pronounced in older than in younger subjects. In the latter, either activation of the sympathetic nervous system or potassium depletion, or both, might counteract the improvement in arterial distensibility caused by blood pressure reduction and sodium depletion. Based on epidemiologic, clinical, and pharmacologic studies, this critical review suggests that, in patients with essential hypertension, changes of sodium intake in diet or administration of diuretics, or both, affect the status of large arteries independently of blood pressure changes.