Calcium supplementation in salt-dependent hypertension.

Area of Science:

• Cardiovascular Physiology
• Mineral Metabolism
• Hypertension Research

Background:

• Salt intake is a major factor in essential hypertension.
• Calcium's role in blood pressure regulation is not fully understood.
• Deoxycorticosterone acetate (DOCA)-salt hypertension in rats mimics human salt-dependent hypertension.

Purpose of the Study:

• To investigate the antihypertensive mechanism of oral calcium loading.
• To assess the effect of calcium supplementation on salt-induced blood pressure elevation.
• To explore calcium's impact on sodium balance and sympathetic activity.

Main Methods:

• Human study: Compared blood pressure response to high salt diet in calcium-supplemented vs. calcium-restricted hypertensive patients.
• Animal study: Evaluated the effect of high calcium intake on DOCA-salt hypertensive rats.
• Measurements included blood pressure, weight gain, urinary sodium excretion, red cell magnesium, and cardiac catecholamines.

Main Results:

• Calcium supplementation significantly attenuated salt-induced blood pressure increases in hypertensive patients.
• High calcium intake reduced blood pressure elevation and sodium retention in DOCA-salt rats.
• Calcium loading increased urinary sodium excretion and red cell magnesium in patients.
• Calcium supplementation decreased cardiac catecholamine levels and improved survival rates in rats.

Conclusions:

• Oral calcium loading may prevent blood pressure rise in salt-dependent hypertension by promoting natriuresis and reducing sodium retention.
• Altered intracellular magnesium levels and normalized sympathetic nervous activity may contribute to calcium's antihypertensive effects.