Dietary calcium supplementation restores pressure natriuresis responses in Dahl-S rats

Calcium supplementation prevents hypertension in Dahl S (DS) rats. Because abnormal pressure natriuresis may contribute to the development of hypertension, we examined the effect of calcium on pressure natriuresis. DS and Dahl R (DR) rats maintained on a 4% sodium diet containing either 0.5% or 2% calcium for 4 weeks were anesthetized; sodium excretion, renal blood flow, and inulin clearance were determined at perfusion pressures of 100, 125, and 156 mm Hg. Inulin clearance and renal blood flow were not different between groups. Sodium excretion increased with increasing renal perfusion pressure in all groups. The slope of the line relating renal perfusion pressure to sodium excretion was greater (P < .05) in DR rats than in DS rats on normal calcium intakes. High calcium intake normalized the slope of the line relating renal perfusion pressure to sodium excretion in DS rats, but had no effect on DR rats. Thus, dietary calcium supplementation normalizes the blunted pressure natriuresis response in the DS rat and may contribute to the prevention of hypertension.