Neurohumoral and hemodynamic responses to dietary calcium supplementation in deoxycorticosterone-salt hypertensive dogs.

We determined whether dietary calcium supplementation can influence the development and maintenance of hypertension in deoxycorticosterone (DOC)-salt-treated dogs. Dogs on normal dietary calcium (0.4%) had significant increases in mean arterial pressure (from 92 +/- 2 to 131 +/- 3 mm Hg, p less than 0.01); those given high dietary calcium (1.7%) had attenuated but significant increases in mean arterial pressure (from 90 +/- 2 to 107 +/- 1, p less than 0.01). The elevation of blood pressure in dogs on normal dietary calcium was primarily due to increased calculated total peripheral resistance, which was prevented by the high calcium diet. The increases in blood pressure could not be attributed to any changes in cardiac output, blood volume, or plasma norepinephrine. These results suggest that mineralocorticoid hypertension in the dog is associated with abnormalities not only in sodium, but also in calcium metabolism. Further, they suggest a direct link between sodium and calcium metabolism and may thus have implications for the pathogenesis and management of salt-dependent hypertension.