Blood pressure effects of calcium intake in experimental models of hypertension.

Calcium intake has been implicated as being an important factor in the development and treatment of hypertension. The mechanisms underlying the relationship between calcium and blood pressure are not yet clearly defined. Experimental studies have documented an inverse association between calcium intake and blood pressure level. For 15 years it has been shown that calcium supplementation is effective in lowering blood pressure in hypertensive rats and, on the other hand, calcium deprivation results in increased blood pressure levels. Enriched calcium diets decrease blood pressure in genetic hypertension displayed by spontaneously hypertensive rats (SHR), stroke-prone SHR, Lyon hypertensive rats or Dahl salt-sensitive rats and, in volume-dependent hypertension induced by saline and mineralocorticoid or angiotensin II administration in Wistar or Sprague-Dawley rats. Efficacy is observed with calcium carbonate added in the diet and with calcium chloride or calcium gluconate in drinking water. Compared with the normal level in the diet (0.5% to 1%), calcium supplementation represents mainly a fourfold increase whose effect is more intense in young weaning animals treated for a long-lasting period (4 to 10 weeks).