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Disturbed calcium metabolism in offspring of hypertensive parents
H Yamakawa1, H Suzuki, M Nakamura
1Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
Insights
Children of hypertensive parents show elevated platelet calcium levels. A high salt diet increased blood pressure in these individuals, linked to calcium metabolism changes, suggesting predictive value for hypertension.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
- Human Genetics
Background:
- Hypertension has a heritable component.
- Calcium metabolism plays a role in blood pressure regulation.
- Disturbances in calcium handling may precede hypertension development.
Purpose of the Study:
- To investigate the heritability of disturbed calcium metabolism in relation to blood pressure.
- To assess calcium and vitamin D responses to salt loading in offspring of hypertensive and normotensive parents.
Main Methods:
- Studied 28 normotensive young adults (offspring of hypertensive or normotensive parents).
- Administered controlled diets with 6g and 20g sodium chloride daily for 7 days each.
- Measured blood pressure, platelet cytosolic calcium concentration ([Ca2+]i), serum electrolytes, plasma renin activity, plasma catecholamines, and urinary excretion.
Main Results:
- Offspring of hypertensive parents had elevated basal platelet [Ca2+]i.
- High salt diet increased mean blood pressure in offspring of hypertensive parents, correlated with basal [Ca2+]i.
- Plasma ionized calcium decreased and 1,25-dihydroxyvitamin D3 increased during high salt intake in this group.
- Increased 1,25-dihydroxyvitamin D3 correlated with blood pressure changes.
Conclusions:
- Disturbed intraplatelet calcium handling may be a heritable trait linked to hypertension.
- Altered systemic calcium metabolism and vitamin D response to salt load are observed in offspring of hypertensive parents.
- These calcium-related metabolic disturbances may predict future hypertension development.
Abstract:
To assess a possible heritability of a disturbed calcium metabolism in relation to blood pressure regulation, 28 young normotensive offspring of either hypertensive or normotensive parents were studied while administered a defined diet with daily sodium chloride of 6 and 20 g/day for 7 days each. Before the high salt diet was begun, the cytosolic calcium concentration ([Ca2+]i) in platelets was elevated in offspring of hypertensive parents, whereas serum electrolytes, plasma renin activity, plasma catecholamines, and 24-hour urinary excretion of sodium and calcium showed no difference between the two groups. On exposure to a high salt diet, the mean blood pressure increased (from 80 +/- 2 to 85 +/- 2 mm Hg, p less than 0.05) in offspring of hypertensive parents. These changes in mean blood pressure were positively correlated with the basal platelet [Ca2+]i (r = 0.61, p less than 0.01), whereas [Ca2+]i did not demonstrate any significant changes. When the subjects were administered the high salt diet, plasma ionized calcium decreased (from 2.37 to 2.21 meq/l, p less than 0.05) and 1,25-dihydroxyvitamin D3 increased (from 32.7 to 40.8 pg/ml, p less than 0.05) with a transient relative hypercalciuria in offspring of hypertensive parents. This increase of 1,25-dihydroxyvitamin D3 was significantly correlated with the changes in mean blood pressure (r = 0.62, p less than 0.01). Disturbed intraplatelet and systemic calcium metabolism may be of predictive value in the development of hypertension.