High-calcium diet prevents salt-induced hypertension and impairment of renal hemodynamics in young spontaneously hypertensive rats.

We studied the effects of a high Ca (4.07%) diet on mean arterial pressure (MAP) and renal hemodynamics in young (6 weeks) spontaneously hypertensive rats (SHR) fed a normal (0.66%) or a high-salt (8.00%) diet for 4 weeks. The high-salt diet accelerated development of hypertension (213 +/- 5 vs. 159 +/- 2 mm Hg, p < 0.01) and increased renal vascular resistance (RVR) (26.4 +/- 2.3 vs. 18.2 +/- 1.2 U, p < 0.01) in young SHR. Simultaneous Ca supplementation prevented the salt-induced increase in MAP (158 +/- 3 mm Hg, p < 0.01) and in RVR (17.3 +/- 1.1 U, p < 0.01). The high-Ca diet did not affect MAP (151 +/- 3 mm Hg, NS) and RVR (17.4 +/- 1.3 U, NS) in young SHR fed a normal salt diet. RVR and MAP were positively correlated in all rats (r = 0.634, n = 38, p < 0.001). The high-Ca diet also prevented salt-induced left ventricular (LV) hypertrophy. Dietary Ca supplementation attenuated the increased salt sensitivity of arterial pressure, possibly by normalizing renal hemodynamics, in salt-loaded young SHR.