Attenuation of deoxycorticosterone-induced hypertension by supplemental dietary calcium

To investigate whether provision of supplemental dietary calcium could attenuate hypertension in the deoxycorticosterone (DOC) model of hypertension we directly measured mean arterial pressure (MAP) in uninephrectomized rats given DOC, a fixed amount of dietary NaCl, and supplemental dietary calcium as CaCO3 or CaCl2. After 4 weeks MAP in rats given 4% dietary calcium as CaCO3 was significantly lower than the in controls given 0.5% calcium as CaCO3. Provision of 2% calcium as CaCO3, however, failed to attenuate hypertension. Provision of just 1% dietary calcium as CaCl2 attenuated hypertension without inducing impaired weight gain or hypophosphataemia. These findings demonstrate that in rats given DOC and NaCl, provision of supplemental dietary calcium can attenuate hypertension. The findings suggest that: (1) the blood pressure response to supplemental calcium can be determined by the anionic component of the calcium salt consumed, and (2) the antihypertensive effect of supplemental calcium is not just a consequence of impaired weight gain or hypophosphataemia.